tag:theconversation.com,2011:/au/topics/microbiology-1225/articlesMicrobiology – The Conversation2024-03-22T12:31:50Ztag:theconversation.com,2011:article/2201902024-03-22T12:31:50Z2024-03-22T12:31:50ZThin, bacteria-coated fibers could lead to self-healing concrete that fills in its own cracks<figure><img src="https://images.theconversation.com/files/578396/original/file-20240227-26-c98ze5.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C5176%2C3437&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cracked roads and sidewalks generate big costs for cities. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/CaliforniaDroughtRain/f93eda16ae2d49ad8539aaf1ad9eb92c/photo?Query=cracked%20concrete&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=260&digitizationType=Digitized&currentItemNo=17&vs=true&vs=true">AP Photo/Marcio Jose Sanchez</a></span></figcaption></figure><p>Some say there are two types of concrete – cracked and on the brink of cracking. But what if when concrete cracked, it could heal itself? </p>
<p><a href="https://research.coe.drexel.edu/caee/aim/">We’re part of a team</a> of <a href="https://scholar.google.com/citations?user=Tn72mFcAAAAJ&hl=en">materials</a> <a href="https://scholar.google.com/citations?user=AtY08c4AAAAJ&hl=en">scientists</a> and microbiologists that has <a href="https://theconversation.com/calcium-munching-bacteria-could-be-a-secret-weapon-against-road-salt-eating-away-at-concrete-roads-and-bridges-113970">harnessed the power of bacteria</a> to create biological fibers that <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">initial results suggest</a> can heal cracks in concrete. We’re working on a technology that, if we work out the kinks and manage to bring it to the market one day, could extend the life span of concrete.</p>
<h2>Cracking concrete</h2>
<p>Picture a bridge exposed to snow, rain, temperature changes and trucks carrying heavy loads. The concrete on the bridge will gradually develop cracks from stress and wear. Over time, these cracks expand, allowing water and corrosive substances that weaken the concrete to penetrate further down. </p>
<p>At some point, local authorities have to pay for repairs, which are not only expensive but also <a href="https://artbabridgereport.org/reports/2022-ARTBA-Bridge-Report.pdf">disrupt traffic and drain public resources</a>.</p>
<p>Now, consider a medical patient recovering from a severe injury. As the patient’s cells recognize the damage, they release tiny healing agents – like microscopic repair crews. These agents target the wounded area, mending tissues and restoring the cells’ functionality. What if concrete had the same kind of <a href="https://doi.org/10.1038/nmat1934">self-healing ability</a> as human tissue? </p>
<h2>A self-healing concrete</h2>
<p><a href="https://research.coe.drexel.edu/caee/aim/people/">Our team</a> at the <a href="https://research.coe.drexel.edu/caee/aim/">Advanced Infrastructure Materials lab</a> at Drexel University was inspired by self-healing tissue in the human body. We developed an addition to concrete we <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">call BioFiber</a>.</p>
<p>BioFiber has <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">three essential functions</a>: It heals itself on its own, it stops cracks from growing wider, and it remains intact inside the concrete when there aren’t any cracks. </p>
<p>Each BioFiber has <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">three key components</a>: a tough core fiber made of a polymer called polyvinyl alcohol, a porous layer of hydrogel infused with <em><a href="https://www.sciencedirect.com/topics/immunology-and-microbiology/lysinibacillus-sphaericus">Lysinibacillus sphaericus</a></em> bacteria, and a damage-responsive outer shell. When cracks hit the BioFiber, its outer shell breaks and releases the bacteria into the crack, which starts the self-healing process.</p>
<p>The strong core fibers in BioFiber <a href="https://doi.org/10.1016/j.conbuildmat.2023.133765">bridge the cracks</a> and stop them from growing wider during the healing process.</p>
<p>Surrounding the core fiber, the hydrogel layer is made up of a mesh of polymer chains at the molecular level that attract water. Their spongelike structure can absorb and hold large volumes of water. During the production process, we add calcium to help the hydrogel solidify. </p>
<p>The hydrogel itself is made up of a <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/alginate">natural polymer found in seaweed called alginate</a>, which has special properties that allow it to trap bacteria. Alginate isn’t toxic and is even safe for biomedical applications such as <a href="https://doi.org/10.1155/2020/8886095">drug delivery</a> and <a href="https://doi.org/10.3390/md21030189">tissue engineering</a>.</p>
<p>The hydrogel <a href="https://www.ncbi.nlm.nih.gov/books/NBK556071">houses endospores</a>, which are dormant bacteria. Once the outer shell cracks and the endospores are awakened from their dormant state, they facilitate the self-healing. </p>
<h2>Activating BioFiber</h2>
<p>The endospores need water to activate. Luckily, the middle hydrogel layer absorbs water well. When the concrete cracks, and water from rain, humidity or street runoff seeps in, the spores wake up. </p>
<p>The spores ingest carbon that we specifically add into the concrete mix, as well as calcium in the concrete itself. With these materials, the bacteria facilitates a chemical reaction called microbially induced calcium carbonate precipitation, or MICCP. This reaction creates <a href="https://doi.org/10.1016/j.dibe.2024.100351">calcium carbonate crystals</a>, which build up and fill in the cracks in the concrete.</p>
<p>The crystal shape varies, from sphere to needle-shaped, and each shape is strong enough to heal the cracks. We can alter the type of crystals the bacteria produces by changing the pH level, calcium source and type of bacteria.</p>
<p>Concrete acts like a solid, tough substance because it’s a mix of cement, sand, gravel and water. We toss the BioFibers into the mix and spread them out as the concrete is mixed, ensuring they’re evenly distributed throughout the mixture.</p>
<p>Once the self-healing process ends and the bacteria dies, the activated BioFiber is done – it can’t heal anymore. But since the concrete has many BioFibers distributed throughout, another fiber can mend the next crack. At the moment, we do not know how many cracks BioFiber concrete can heal, and we’re conducing more research to figure that out. </p>
<p>To feed the bacteria, we add the amount of food it needs to stay alive and heal the cracks, depending on how many cracks we anticipate them having to fix. When the bacteria runs out of food, the process stops. The bacteria can live for roughly a couple of weeks during the healing process. </p>
<p>While BioFiber shows initial promise, it does have shortcomings, which could make manufacturing it at a larger scale challenging. The manufacturing process and materials used are specialized and not always affordable and practical. While our first tests suggest that BioFiber extends the life span of concrete, we’ll need more testing, including field trials, to verify those early results.</p>
<p>We hope to eventually commercialize and manufacture the fibers at larger production scales, while in the meantime we continue to run tests and study how to improve BioFiber’s self-healing abilities. We’d like to one day get these fibers into roads and sidewalks to potentially prevent cracking in aging concrete.</p><img src="https://counter.theconversation.com/content/220190/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mohammad Houshmand works for Drexel University. He receives funding from the National Science Foundation.</span></em></p><p class="fine-print"><em><span>Yaghoob Farnam receives funding from the National Science Foundation. In addition to his role as an associate professor at Drexel University, he is co-founder and senior technical advisor for SusMaX Inc. </span></em></p>Your skin heals from cuts and scrapes on its own − what if concrete could do that too?Mohammad Houshmand, Ph.D. Candidate in Civil Engineering, Drexel UniversityYaghoob Farnam, Assistant Professor of Civil Engineering, Drexel UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2202832024-02-22T13:42:50Z2024-02-22T13:42:50ZBacteria can develop resistance to drugs they haven’t encountered before − scientists figured this out decades ago in a classic experiment<figure><img src="https://images.theconversation.com/files/575458/original/file-20240213-24-7w1h4o.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2048%2C1480&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bacteria are evolutionarily primed to outpace drug developers.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nihgov/28881401596/in/photolist-U4kMcq-c57xDd-L19JtW-c9uWe5-dYBMYW-a5tw3L-2joPCWz-2jfgs7P-9VPmA4-fuUV2g-fvxv6D-ot5Jyg-fvacBd-vughy5-7NapMs-7N7qSL-yrSV6f-7N5dpc-Mj3KFR-7Na6i5-ysPK3x-7Na5Wq-ftHb6n-ftXtfs-ftH7Vt-7Na6P5-tCCMPo-xvLN1S-ybiGai-yqtCoy-982F9z-ftHaAP-7N3qKg-7N674D-fvxufn-fvMDps-x2Btgv-ftHapZ-7Na6sy-7NaoHs-fuUUt8-fuUQjz-fvxptp-fuUXN2-7U2mNs-7N66b2-fvaabC-xtGans">National Institute of Allergy and Infectious Diseases, National Institutes of Health/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Do bacteria mutate randomly, or do they mutate for a purpose? Researchers have been <a href="https://doi.org/10.1017/S0022172400017125">puzzling over this conundrum for over a century</a>.</p>
<p>In 1943, microbiologist Salvador Luria and physicist turned biologist Max Delbrück <a href="https://doi.org/10.1080/09332480.2010.10739800">invented an experiment</a> to argue that bacteria mutated aimlessly. Using their test, other scientists showed that bacteria could acquire resistance to antibiotics they hadn’t encountered before.</p>
<p>The <a href="https://doi.org/10.1080/09332480.2010.10739800">Luria–Delbrück experiment</a> has had a significant effect on science. The findings helped Luria and Delbruck win the <a href="https://www.nobelprize.org/prizes/medicine/1969/summary/">Nobel Prize in physiology or medicine in 1969</a>, and students today learn this experiment in <a href="https://doi.org/10.1128/jmbe.00161-23">biology classrooms</a>. I have been studying this experiment in my work as a biostatistician for <a href="https://doi.org/10.1016/S0025-5564(99)00045-0">over 20 years</a>.</p>
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<p>Decades later, this experiment offers lessons still relevant today, because it implies that bacteria can develop resistance to antibiotics that haven’t been developed yet.</p>
<h2>Slot machines and a eureka moment</h2>
<p>Imagine a test tube containing bacteria living in nutrient broth. The broth is cloudy due to the high concentration of bacteria within it. Adding a virus that infects bacteria, <a href="https://theconversation.com/viruses-are-both-the-villains-and-heroes-of-life-as-we-know-it-169131">also known as a phage</a>, into the tube kills most of the bacteria and makes the broth clear.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of bacteriophage structure." src="https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1014&fit=crop&dpr=1 600w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1014&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1014&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1274&fit=crop&dpr=1 754w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1274&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1274&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bacteriophages are viruses that specifically infect bacteria.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/flat-illustration-of-bacteriophage-royalty-free-illustration/1285360925">Kristina Dukart/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>However, keeping the test tube under conditions favorable for bacterial growth will turn the broth cloudy again over time. This indicates that the bacteria developed resistance against the phages and were able to proliferate.</p>
<p>What role did the phages play in this change?</p>
<p>Some scientists thought the phages incited the bacteria to mutate for survival. Others suggested that bacteria routinely mutate randomly, and the development of phage-resistant variants was simply <a href="https://doi.org/10.1128/jb.28.6.619-639.1934">a lucky outcome</a>. Luria and Delbrück had been working together for months to solve this conundrum, but none of their experiments had been successful. </p>
<p>On the night of Jan. 16, 1943, Luria got a hint about how to crack the mystery while watching a colleague hit the jackpot at a slot machine. The next morning, he hurried to his lab.</p>
<p>Luria’s experiment consisted of a few tubes and dishes. Each tube contained nutrient broth that would help the bacteria <em>E. coli</em> multiply, while each dish contained material coated with phages. A few bacteria were placed into each tube and given two opportunities to generate phage-resistant variants. They could either mutate in the tubes in the absence of phages, or they could mutate in the dishes in the presence of phages.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of six test tubes and and six petri dishes, a few of the dishes containing red dots" src="https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=348&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=348&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=348&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This diagram of the Luria-Delbrück experiment depicts colonies of phage-resistant variants of <em>E. coli</em> (red) developing in petri dishes.</span>
<span class="attribution"><span class="source">Qi Zheng</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The next day, Luria transferred the bacteria in each tube into a dish filled with phages. The day after that, he counted the number of resistant bacterial colonies in each dish. </p>
<p>If bacteria develop resistance against phages by interacting with them, none of the bacteria in the tubes should have mutations. On the other hand, only a few of the bacteria – say, 1 out of 10 million bacteria – should spawn resistant variants when they are transferred into a dish containing phages. Each phage-resistant variant would grow into a colony, but the remaining bacteria would die from infection.</p>
<p>If bacteria develop resistance independently of interacting with phages, some of the bacteria in the tubes will have mutations. This is because each time a bacterium divides in a tube, it has a small probability of spawning a resistant variant. If the starting generation of bacteria is the first to mutate, at least half of the bacteria will be resistant in later generations. If a bacterium in the second generation is the first to mutate, at least an eighth of the bacteria will be resistant in later generations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Four tree diagrams of green and red circles, with subsequent branches from red dots turning red" src="https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=427&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mutations that confer resistance against phages (red) early on will spawn a large number of phage-resistant variants, while mutations that occur later on will spawn only a few resistant variants.</span>
<span class="attribution"><span class="source">Qi Zheng</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Like small-prize cash-outs in slot machines, late-generation mutations occur more often but give fewer resistant variants. Like jackpots, early-generation mutations occur rarely but give large numbers of variants. Early-generation mutations are rare because early on there are only a small number of bacteria available to mutate.</p>
<p>For example, in a 20-generation experiment, a mutation occurring at the 10th generation of bacteria would give 1,024 phage-resistant variants. A mutation occurring at the 17th generation would give only four phage-resistant variants. </p>
<p>The number of resistant colonies in Luria’s experiments showed a similar pattern to that of slot machine cash-outs. Most dishes contained no or small numbers of mutant colonies, but several contained a large number of mutant colonies that Luria considered jackpots. This meant that the bacteria developed resistant variants before they interacted with the phages in the dishes.</p>
<h2>An experiment’s legacy</h2>
<p>Luria sent a note to Delbrück after his experiment was completed, asking him to check his work. The two scientists then worked together to write <a href="https://doi.org/10.1093/genetics/28.6.491">a classic paper</a> describing the experimental protocol and a theoretical framework to measure bacterial mutation rates.</p>
<p>Other scientists conducted similar experiments by replacing phages <a href="https://doi.org/10.1073/pnas.31.1.16">with penicillin</a> and with <a href="https://doi.org/10.1128/am.20.5.810-814.1970">tuberculosis drugs</a>. Similarly, they found that bacteria did not need to encounter an antibiotic to acquire resistance to it.</p>
<p>Bacteria have relied on random mutations to cope with harsh, constantly changing environments <a href="https://theconversation.com/antibiotic-resistance-is-not-new-it-existed-long-before-people-used-drugs-to-kill-bacteria-115836">for millions of years</a>. Their incessant, random mutations will lead them to inevitably develop variants that are resistant to the antibiotics of the future. </p>
<p>Drug resistance is a reality of life we will have to accept and continue to fight against.</p><img src="https://counter.theconversation.com/content/220283/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Qi Zheng does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The Nobel Prize-winning Luria−Delbrück experiment showed that random mutations in bacteria can allow them to develop resistance by chance.Qi Zheng, Professor of Biostatistics, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2202782024-02-08T13:40:17Z2024-02-08T13:40:17ZSugary handshakes are how cells talk to each other − understanding these name tags can clarify how the immune system works<figure><img src="https://images.theconversation.com/files/570832/original/file-20240123-29-c6ob1s.png?ixlib=rb-1.1.0&rect=0%2C0%2C2880%2C1664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Handshakes between glycans are one way cells recognize each other.</span> <span class="attribution"><span class="source">Kelvin Anggara</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Like the people they make up, cells communicate by bumping into one another and exchanging handshakes. Unlike people, cells perform these handshakes using the diverse range of sugar molecules coating their surface like trees covering a landscape. Handshakes between these <a href="https://doi.org/10.1093/glycob/cww086">sugar molecules, or glycans</a>, trigger cells to react in specific ways toward each other, such as escape, ignore or destroy.</p>
<p>Figuring out the “body language” of glycans during these handshakes can provide clues to how cancers, infections and immune systems work, as well as solutions to health and sustainability challenges society faces today.</p>
<h2>What are glycans?</h2>
<p>Each glycan molecule is made up of a network of individual sugar molecules bonded together. The vast number of possible glycan structures that can be built from connecting these sugar molecules together allows glycans to <a href="https://doi.org/10.1093/glycob/cww086">store rich information</a>.</p>
<p>Because all living cells are covered with sugars, glycans act like ID cards for cells. They display the cell’s identity, such as whether it’s a bacteria or human cell, and its state, such as whether it’s healthy or cancer, to the rest of the body and allow <a href="https://www.ncbi.nlm.nih.gov/books/NBK579984/">other cells to recognize</a> and respond to it. For example, these identifying signs allow our immune cells to recognize and clear out harmful bacteria and cancerous cells while leaving healthy cells in peace.</p>
<p>An example of how glycan-stored information is important to daily life is <a href="https://theconversation.com/what-are-blood-types-126002">your blood type</a>. Glycans are chemically bonded to proteins and lipids on the surface of red blood cells. Notably, the surface of type A red blood cells have glycans that differ from the glycans on the surface of type B and type O red blood cells. Knowing what blood type you have is important to avoid an unwanted immune response during blood transfusions.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/570449/original/file-20240120-22-n2v4b4.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing the glycan structures of types A, B and O red blood cells" src="https://images.theconversation.com/files/570449/original/file-20240120-22-n2v4b4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/570449/original/file-20240120-22-n2v4b4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=505&fit=crop&dpr=1 600w, https://images.theconversation.com/files/570449/original/file-20240120-22-n2v4b4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=505&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/570449/original/file-20240120-22-n2v4b4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=505&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/570449/original/file-20240120-22-n2v4b4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=635&fit=crop&dpr=1 754w, https://images.theconversation.com/files/570449/original/file-20240120-22-n2v4b4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=635&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/570449/original/file-20240120-22-n2v4b4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=635&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Your blood type is determined by the types of glycans, depicted here in circles and triangles, on your red blood cells.</span>
<span class="attribution"><span class="source">Kelvin Anggara/Created with BioRender.com</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Proteins decorated with glycans, or glycoproteins, and lipids decorated with glycans, or glycolipids, are ubiquitous in nature. </p>
<p>For example, distinctive glycoproteins cover the surface of the viruses that cause <a href="https://doi.org/10.1021/acscentsci.0c01056">COVID-19</a>, <a href="https://doi.org/10.1016/j.cell.2016.04.010">HIV</a> and <a href="https://doi.org/10.1021/acscentsci.2c00981">H1N1 influenza</a> and help them <a href="https://theconversation.com/how-do-viruses-get-into-cells-their-infection-tactics-determine-whether-they-can-jump-species-or-set-off-a-pandemic-216139">infect cells</a>. Glycolipids also coat <a href="https://doi.org/10.1016%2Fj.cell.2019.12.006">many bacteria</a>, allowing them to stick to their hosts and protect them from viruses and immune cells.</p>
<p>More recently, researchers discovered pieces of <a href="https://doi.org/10.1016/j.cell.2021.04.023">genetic material decorated with glycans</a> on the surfaces of mammalian cells, challenging the long-standing notion that genetic material could be found only in the nucleus of cells and launching research to determine the functions of these glycans. One recent study showed that these molecules are vital in <a href="https://doi.org/10.1016/j.cell.2023.12.033">attracting immune cells</a> toward infected or injured tissues.</p>
<h2>How do cells read glycans?</h2>
<p>In addition to the rich biological information contained in glycans, their easily accessible locations on cell surfaces make them highly attractive targets in scientific research and drug development.</p>
<p>Cells sense glycans on the surfaces of other cells by using <a href="https://www.ncbi.nlm.nih.gov/books/NBK579947/">proteins called lectins</a>, among others. Each lectin has a unique area that allows it to bind to glycans with a specific matching sequence, triggering complex signals that lead to a biological action.</p>
<p>For example, a subfamily of lectins called <a href="https://doi.org/10.1038/nri2569">C-type lectins</a> are able to recognize the specific glycans on the outer walls of harmful viruses, fungi and bacteria. Found on surfaces of certain immune cells, these lectins deliver the glycans to proteins on other immune cells that can now selectively destroy any viruses or cells that carry that glycan. This process allows the immune system to clear the body of harmful pathogens. For example, these lectins recognize glycans on the <a href="https://doi.org/10.1093/glycob/cwy023">surfaces of cancer cells</a> and direct other immune cells to eliminate these cancer cells.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/572940/original/file-20240201-25-cjkqvl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of a spherical influenza virus, with red and blue spikes studding its surface" src="https://images.theconversation.com/files/572940/original/file-20240201-25-cjkqvl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/572940/original/file-20240201-25-cjkqvl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572940/original/file-20240201-25-cjkqvl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572940/original/file-20240201-25-cjkqvl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572940/original/file-20240201-25-cjkqvl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572940/original/file-20240201-25-cjkqvl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572940/original/file-20240201-25-cjkqvl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The spikes on the surface of the influenza virus are composed of glycoproteins.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/flu-virus-close-up-view-3d-illustration-royalty-free-image/1389473291">Dr_Microbe/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Another type of <a href="https://doi.org/10.1146/annurev-immunol-102419-035900">lectin called siglecs</a> are found on surfaces of immune cells and help them distinguish self from nonself, that is, between the cells that make up the body and the cells that are foreign to the body. Because siglecs are involved in <a href="https://doi.org/10.1146/annurev-immunol-102419-035900">controlling how the immune system responds</a> to many cancers, allergies, autoimmune diseases and neurodegeneration, they offer an opportunity to treat these conditions.</p>
<p>The early success of glycan-based drugs is exemplified by <a href="https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5911a1.htm">Pfizer’s Prevnar vaccine</a> to prevent bacterial pneumonia, which was approved by the Food and Drug Administration in 2010. Prevnar contains glycans from various strains of <a href="https://doi.org/10.5863%2F1551-6776-21.1.27"><em>Streptococcus pneumoniae</em></a>, the leading cause of bacterial pneumonia in children and adults. The bacterial glycans in the vaccine trigger an immune response when immune cells recognize the glycans as foreign threats. Once immune cells learn how to neutralize the threat, the body becomes immune to future invasion by bacteria with the same glycans. </p>
<h2>Examining every sugar molecule</h2>
<p>Because scientists are still <a href="https://doi.org/10.1021/jacs.9b06406">unable to extract all the biological information</a> in glycans, their full potential as treatments has remained untapped. Comprehensively extracting all the information stored in glycans is very difficult because there isn’t currently technology able to analyze the complex and diverse structures of glycans. Researchers still don’t know what these “sugar codes” look like and how they function.</p>
<p>Individual glycans are composed of sugar molecules in unique arrangements, but current analytical tools can only <a href="https://doi.org/10.17226/13446">simultaneously analyze many glycans</a>. To see why this is a problem for analysis, imagine all the glycans in a cell as candies in a jar. Some of them are the same colors and some are not. It would be difficult to identify and quantify the color of every candy in the jar if you’re unable to pour them out to individually sort through each one of them.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/570447/original/file-20240120-27-59622g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Jar of colorful candy on a table" src="https://images.theconversation.com/files/570447/original/file-20240120-27-59622g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/570447/original/file-20240120-27-59622g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/570447/original/file-20240120-27-59622g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/570447/original/file-20240120-27-59622g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/570447/original/file-20240120-27-59622g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=508&fit=crop&dpr=1 754w, https://images.theconversation.com/files/570447/original/file-20240120-27-59622g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=508&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/570447/original/file-20240120-27-59622g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=508&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Can you identify the color of every candy and count how many there are of each color without opening the jar?</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/round-candies-in-clear-glass-jar-with-clamp-lid-lW25Zxpkln8">Clem Onojeghuo/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p><a href="https://anggara.science">My lab</a> <a href="https://scholar.google.ca/citations?user=1SkTHegAAAAJ&hl=en">is confronting</a> this challenge by developing imaging technology that can analyze the structure of glycans by <a href="https://doi.org/10.1126/science.adh3856">imaging each individual molecule</a>. Essentially, we’re developing a technique to open the jar and study every single candy one at a time.</p>
<p>In the long run, my team aspires to unveil how these glycans present themselves to the proteins that recognize them and, finally, reveal the very language that cells use to express themselves.</p><img src="https://counter.theconversation.com/content/220278/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kelvin Anggara works for the Max Planck Institute for Solid State Research and receives funding from the European Research Council under Project GlycoX (101075996).</span></em></p>Sugar molecules called glycans cover the surface of all cells, acting as ID cards that broadcast what they are to the rest of the body.Kelvin Anggara, Group leader in Single molecule imaging, Max Planck Institute for Solid State ResearchLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2160832024-01-09T00:57:38Z2024-01-09T00:57:38ZHow often should you wash your sheets and towels?<figure><img src="https://images.theconversation.com/files/558552/original/file-20231109-17-a2kns6.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C7536%2C5026&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/laundry-fresh-woman-smelling-towel-after-2246392501">PeopleImages.com - Yuri A/Shutterstock</a></span></figcaption></figure><p>Everyone seems to have a different opinion when it comes to how often towels and <a href="https://7news.com.au/video/lifestyle/cleaning/dr-karl-on-how-often-you-should-wash-our-sheets-bc-6320410318112">bed sheets should be washed</a>. While many people might wonder whether days or weeks is best, in one survey from the United Kingdom, <a href="https://www.bbc.com/news/newsbeat-61259074">almost half of single men</a> reported not washing their sheets for up to four months at a time. </p>
<p>It’s fairly clear that four months is too long to leave it, but what is the ideal frequency? </p>
<p>Bed linen and towels are quite different and so should be washed at different intervals. While every week or two will generally suffice for sheets, towels are best washed every few days.</p>
<p>Anyway, who doesn’t love the feeling of a fresh set of sheets or the smell of a newly laundered towel?</p>
<h2>Why you should wash towels more often</h2>
<p>When you dry yourself, you deposit thousands of <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2018.02362/full">skin cells</a> and millions of <a href="https://www.ajicjournal.org/article/S0196-6553(23)00402-9/fulltext">microbes</a> onto the towel. And because you use your towel to dry yourself after a shower or bath, your towel is regularly damp.</p>
<p>You also deposit a hefty amount of dead skin, microbes, sweat and oils <a href="https://theconversation.com/your-bed-probably-isnt-as-clean-as-you-think-a-microbiologist-explains-163513">onto your sheets</a> every night. But unless you’re a prolific night sweater, your bedding doesn’t get wet after a night’s sleep. </p>
<p>Towels are also made of a thicker material than sheets and therefore tend to stay damp for longer. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/all-the-reasons-you-might-be-having-night-sweats-and-when-to-see-a-doctor-211436">All the reasons you might be having night sweats – and when to see a doctor</a>
</strong>
</em>
</p>
<hr>
<p>So what is it about the dampness that causes a problem? Wet towels are a breeding ground for bacteria and moulds. <a href="https://www.qld.gov.au/housing/public-community-housing/public-housing-tenants/looking-after-your-home/safety/mould">Moulds</a> especially love <a href="https://www.asthmaandlung.org.uk/living-with/indoor-air-pollution/allergies">damp environments</a>. Although mould won’t necessarily be visible (you would need significant growth to be able to see it) this can lead to an unpleasant smell.</p>
<p>As well as odours, <a href="https://www.nhs.uk/common-health-questions/infections/can-clothes-and-towels-spread-germs/">exposure to these microbes</a> in your towels and sheets can cause <a href="https://aafa.org/allergies/types-of-allergies/insect-allergy/dust-mite-allergy/">asthma</a>, allergic skin irritations, or other <a href="https://wwwnc.cdc.gov/eid/article/11/4/04-1094_article">skin infections</a>.</p>
<figure class="align-center ">
<img alt="A couple changing the sheets on their bed." src="https://images.theconversation.com/files/558551/original/file-20231109-17-6185x9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558551/original/file-20231109-17-6185x9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558551/original/file-20231109-17-6185x9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558551/original/file-20231109-17-6185x9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558551/original/file-20231109-17-6185x9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558551/original/file-20231109-17-6185x9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558551/original/file-20231109-17-6185x9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">People don’t always agree on how often to change the sheets.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/black-couple-changing-bed-sheet-together-1051726535">Rawpixel.com/Shutterstock</a></span>
</figcaption>
</figure>
<h2>So what’s the ideal frequency?</h2>
<p>For bedding, it really depends on factors such as whether you have a bath or shower just before going to bed, or if you fall into bed after a long, sweaty day and have your shower in the morning. You will need to wash your sheets more regularly in the latter case. As a rule of thumb, once a week or every two weeks should be fine. </p>
<p>Towels should ideally be washed more regularly – perhaps every few days – while your facecloth should be cleaned after every use. Because it gets completely wet, it will be wet for a longer time, and retain more skin cells and microbes. </p>
<p>Wash your towels at a high temperature (for example, 65°C) as that will <a href="https://pubmed.ncbi.nlm.nih.gov/34465009/">kill many microbes</a>. If you are conscious of saving energy, you can use a lower temperature and add a cup of vinegar to the wash. The vinegar will kill microbes and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8231443/">prevent bad smells</a> from developing. </p>
<p>Clean your washing machine regularly and dry the fold in the rubber after every wash, as this is another place microbes like to grow. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/research-check-can-tea-towels-cause-food-poisoning-98152">Research Check: can tea towels cause food poisoning?</a>
</strong>
</em>
</p>
<hr>
<h2>Smelly towels</h2>
<p>What if you regularly wash your towels, but they still smell bad? One of the reasons for this pong could be that you’ve left them in the washing machine too long after the wash. Especially if it was a warm wash cycle, the time they’re warm and damp will allow microbes to happily grow. Under <a href="https://textbookofbacteriology.net/growth_3.html">lab conditions</a> the number of these bacteria can double every 30 minutes.</p>
<p>It’s important to hang your towel out to dry after use and not to leave towels in the washing machine after the cycle has finished. If possible, hang your towels and bedding out in the sun. That will dry them quickly and thoroughly and will foster that lovely fresh, clean cotton smell. Using a dryer is a good alternative if the weather is bad, but outdoors in the sun is always better if possible.</p>
<p>Also, even if your towel is going to be washed, don’t throw a wet towel into the laundry basket, as the damp, dirty towel will be an ideal place for microbes to breed. By the time you get to doing your washing, the towel and the other laundry around it may have acquired a bad smell. And it can be difficult to get your towels smelling fresh again. </p>
<figure class="align-center ">
<img alt="A young woman loading a washing machine." src="https://images.theconversation.com/files/558550/original/file-20231109-15-2gv66g.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6709%2C4476&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558550/original/file-20231109-15-2gv66g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558550/original/file-20231109-15-2gv66g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558550/original/file-20231109-15-2gv66g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558550/original/file-20231109-15-2gv66g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558550/original/file-20231109-15-2gv66g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558550/original/file-20231109-15-2gv66g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Towels should be washed more often than sheets.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-woman-taking-laundry-out-washing-1727564893">New Africa/Shutterstock</a></span>
</figcaption>
</figure>
<h2>What about ‘self-cleaning’ sheets and towels?</h2>
<p>Some companies sell “quick-dry” towels or “self-cleaning” towels and bedding. Quick-dry towels are made from synthetic materials that are weaved in a way to allow them to dry quickly. This would help prevent the growth of microbes and the bad smells that develop when towels are damp for long periods of time.</p>
<p>But the notion of self-cleaning products is more complicated. Most of these products contain <a href="https://www.degruyter.com/document/doi/10.1515/chem-2016-0005/html">nanosilver</a> or copper, antibacterial metals that kill micro-organisms. The antibacterial compounds will stop the growth of bacteria and can be useful to limit smells and reduce the frequency with which you need to clean your sheets and towels. </p>
<p>However, they’re not going to remove dirt like oils, skin flakes and sweat. So as much as I would love the idea of sheets and towels that clean themselves, that’s not exactly what happens. </p>
<p>Also, excessive use of antimicrobials <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6636436/pdf/idr-12-1985.pdf">such as nanosilver</a> can lead to <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2021.652863/full">microbes becoming resistant</a> to them.</p><img src="https://counter.theconversation.com/content/216083/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rietie Venter received funding from various national and international funding bodies.</span></em></p>While every week or two will generally suffice for sheets, towels are best washed every few days. A microbiologist explains.Rietie Venter, Associate professor, Clinical and Health Sciences, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2205642024-01-05T14:54:09Z2024-01-05T14:54:09ZNew antibiotic zosurabalpin shows promise against drug-resistant bacteria – an expert explains how it works<figure><img src="https://images.theconversation.com/files/567989/original/file-20240105-24-a6i28q.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5120%2C2880&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Carbapenem-resistant Acinetobacter baumannii is classified as a priority 1 critical pathogen by the World Health Organization</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/medical-science-laboratory-portrait-beautiful-black-1922200124">Gorodenkoff/Shutterstock</a></span></figcaption></figure><p>Researchers have <a href="https://www.nature.com/articles/s41586-023-06799-7">identified</a> an entirely new class of antibiotic that can kill bacteria that are resistant to most current drugs. </p>
<p>Zosurabalpin is highly effective against the bacterium carbapenem-resistant <em>Acinetobacter baumannii</em> (Crab), which is <a href="https://www.who.int/news/item/27-02-2017-who-publishes-list-of-bacteria-for-which-new-antibiotics-are-urgently-needed">classified</a> as a “priority 1” pathogen by the World Health Organization due to its growing presence in hospitals.</p>
<p>Crab <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9137960/">can kill</a> up to 60% of people infected with it. It commonly causes infections of the urinary tract, respiratory tract and blood stream, potentially leading to sepsis. It is responsible for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6913636/">around 20%</a> of infections in places like hospitals, care homes or other similar healthcare settings.</p>
<p>Antibiotics commonly work by crossing the cell wall that surrounds infectious bacteria to reach the vital machinery inside. Once inside the cell, antibiotics block that machinery in such a way as to either stop the bacteria from growing or to cause cell death. </p>
<p>Crab is a clinical challenge as it has a double-layered cell wall, a feature that microbiologists describe as “<a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/gram-negative-bacteria">gram negative</a>”. This means that antibiotics need to cross both layers to reach the vital machinery inside the bacteria to kill them and treat the infection. </p>
<p>An exception to this rule is penicillin-based antibiotics, where the target is in the cell wall itself. These antibiotics, known as <a href="https://www.bmj.com/content/344/bmj.e3236">carbapenems</a>, were derived from penicillin some 48 years after it was first discovered and still work in the same way. However, they have undergone clever chemical modification to prevent bacteria successfully evolving to resist them. This makes them a vital part of treating infections like those caused by <em>Acinetobacter baumannii</em>. </p>
<p>But Crab, the superbug version of this infection, has developed the ability to break down carbapenems, giving it an evolutionary upper hand, which has led to its rise to supremacy in hospitals. </p>
<h2>Zosurabalpin</h2>
<p>This new class of antibiotic, zosurabalpin, is shown to be highly effective against Crab both in the laboratory and in infected animals. Researchers tested zosurabalpin against more than 100 Crab samples from patients suffering from the infection. The research team, <a href="https://www.nature.com/articles/s41586-023-06799-7">found</a> that zosurabalpin was able to kill all of these bacterial strains. It could also kill the bacteria in the bloodstream of mice infected with Crab, preventing them from developing sepsis. </p>
<p>Crab has the ability to make a toxin called <a href="https://www.sciencedirect.com/topics/neuroscience/lipopolysaccharide">lipopolysaccharide</a> that it uses as part of its weaponry for infecting people and which it normally embeds into its outer cell wall. </p>
<p>Zosurabalpin works by blocking a molecular machine called <a href="https://www.nature.com/articles/s41586-023-06873-0">LptB2FGC</a> that transports the lipopolysaccharide toxin from the inside barrier to the outside one. This makes the toxin build up inside the bacteria, causing the Crab cells to die. Essentially, the bacteria pull the pin out of their own grenade but zosurabalpin stops them from being able to throw it. </p>
<p>This LptB2FGC mechanism is pretty unique to Crab, which has some advantages and disadvantages. The bad news is that zosurabalpin will only kill Crab infections and not those caused by other types of bacteria. This means doctors would need to accurately diagnose patients with this infection to decide if zosurabalpin would be the right drug. </p>
<p>But a major advantage is that the chance of antibiotic resistance emerging is reduced, as this resistance could only emerge from Crab and not other types of bacteria. Hopefully, this could extend the shelf life of this drug. </p>
<p>The researchers say they have already seen some mutations in the drug target, LptB2FGC. However, these only seem to reduce the effectiveness of zosurabalpin, rather than stopping it working entirely. The great news is that this is the first time an antibiotic has been reported to work in this way. It gives microbiologists a new avenue to explore ways to kill our bacterial enemies before they kill us. </p>
<figure class="align-center ">
<img alt="Close up of microscope with lab glassware." src="https://images.theconversation.com/files/568021/original/file-20240105-25-qzeyh5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568021/original/file-20240105-25-qzeyh5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568021/original/file-20240105-25-qzeyh5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568021/original/file-20240105-25-qzeyh5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568021/original/file-20240105-25-qzeyh5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568021/original/file-20240105-25-qzeyh5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568021/original/file-20240105-25-qzeyh5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Zosurabalpin is effective against the bacteria, Crab, which can kill up to 60% of people infected with it.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/microscope-lab-glassware-science-laboratory-research-530971462">totojang1977/Shutterstock</a></span>
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<p>Zosurabalpin is now in phase 1 clinical trial for use in patients infected with Crab. This early testing in humans will help the company developing the drug, Roche, to work out any side effects of the drugs as well as potential toxicity. Most importantly, they need to check that the drug works just as well in humans as it did in mice, and look to see if any antibiotic resistance emerges in the trial patients. </p>
<p>It’s early days and the failure rate for new antibiotic development is high, but scientists are rising to the challenge. This discovery offers significant opportunities to the scientific field as a whole and a vital lifeline in the fight against antibiotic-resistant infections.</p><img src="https://counter.theconversation.com/content/220564/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonathan Cox receives research funding from UKRI, charities and industry.
He is Co-Director of the Antibiotic Discovery Accelerator (ABX) Network </span></em></p>Zosurabalpin is highly effective against dangerous bacterium Crab, which can kill up to 60% of people infected with it.Jonathan Cox, Senior Lecturer in Microbiology, Aston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2134512023-11-07T19:35:15Z2023-11-07T19:35:15ZHow do bacteria actually become resistant to antibiotics?<figure><img src="https://images.theconversation.com/files/555508/original/file-20231024-24-2win4c.jpg?ixlib=rb-1.1.0&rect=0%2C817%2C5928%2C3745&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/a-person-holding-a-round-object-in-their-hands-y--8fqaK1kY">CDC/Unsplash</a></span></figcaption></figure><p><em>Antimicrobial resistance is <a href="https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance">one of the biggest global threats</a> to health, food security and development. This month, The Conversation’s experts <a href="https://theconversation.com/au/topics/the-dangers-of-antibiotic-resistance-146983">explore how we got here and the potential solutions</a>.</em></p>
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<p>“What doesn’t kill me makes me stronger”, originally coined by <a href="https://www.dictionary.com/e/slang/what-doesnt-kill-you-makes-you-stronger/">Friedrich Nietzsche in 1888</a>, is a perfect description of how bacteria develop <a href="https://www.nps.org.au/consumers/antibiotics-explained#what-is-antibiotic-resistance?">antibiotic resistance</a>. </p>
<p>Contrary to a common belief, antibiotic resistance <a href="https://www.cdc.gov/antibiotic-use/images/Infographic-AR-bacteria.jpg">is not</a> about your body becoming resistant to antibiotics. </p>
<p>Resistance arises when bacteria are exposed to levels of antibiotics that don’t immediately kill them. They develop defences that prevent the same antibiotic from harming them in the future, even at higher doses.</p>
<h2>How bacteria adapt</h2>
<p>The ability for bacteria to adapt lies in part with their astonishing rate of reproduction. Some species, such as <em>Escherichia coli</em>, can <a href="https://www.youtube.com/watch?v=gEwzDydciWc">replicate</a> as quickly as every 20 minutes, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6015860/">depending on the environment</a>. One bacterium can become more than 68 billion bacteria in 12 hours.</p>
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Read more:
<a href="https://theconversation.com/im-a-microbiologist-and-heres-what-and-where-i-never-eat-213404">I'm a microbiologist and here's what (and where) I never eat</a>
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<p>However, bacteria don’t faithfully reproduce their genetic code, and mutations can slip in every generation. </p>
<p>While most changes are bad, sometimes they can help the bacteria grow in the presence of an antibiotic. This “new and improved” population <a href="https://www.cdc.gov/antibiotic-use/images/Infographic-how-AR-happens.jpg">quickly takes over</a>.</p>
<p>Additional mutations enable survival at even higher antibiotic concentrations.</p>
<p>This evolution of resistance can be seen by growing bacteria on a large agar plate (a nutrient support that bacteria like to grow on) with zones of increasing antibiotic levels. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/plVk4NVIUh8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Watch how bacteria develop resistance to extremely high concentrations of antibiotics (Harvard Medical School).</span></figcaption>
</figure>
<p>Growth is halted when they first encounter the next zone, but once they have developed resistance they quickly expand until they reach the next region with more antibiotic. </p>
<p>Bacteria in your body can easily develop resistance in a similar manner during the typical seven- to ten-day course of antibiotic treatment.</p>
<h2>They also exchange genetic material</h2>
<p>The other key mechanism enabling bacterial resistance is the <a href="https://www.cdc.gov/drugresistance/pdf/threats-report/How-AR-Moves-508.pdf">exchange of genetic information</a> between bacteria. </p>
<p>In addition to the main chunk of DNA that encodes the bacterial genome, bacteria can host circular DNA snippets called plasmids. These plasmids are <a href="https://asm.org/Articles/2023/January/Plasmids-and-the-Spread-of-Antibiotic-Resistance-G">readily exchanged between bacteria</a>, including different species.</p>
<p>Plasmid exchange usually occurs by direct physical contact between bacteria. Bacteria are promiscuous, so this can happen a lot! Once inside a bacteria, plasmids can be passed down to the next generation. </p>
<p>Unfortunately, plasmids are <a href="https://www.annualreviews.org/doi/10.1146/annurev.biochem.78.082907.145923?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed">particularly good</a> at encoding multiple resistance genes.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/rising-antibiotic-resistance-in-utis-could-cost-australia-1-6-billion-a-year-by-2030-heres-how-to-curb-it-149543">Rising antibiotic resistance in UTIs could cost Australia $1.6 billion a year by 2030. Here's how to curb it</a>
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</em>
</p>
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<h2>4 ways bacteria resist</h2>
<p>Bacteria develop resistance to antibiotic treatment using four main methods:</p>
<p><strong>1) Keep the antibiotic out.</strong> Bacteria are good at keeping unwanted molecules from getting inside. </p>
<p>Gram-positive bacteria like <em>Staphylococcus aureus</em> have a thick cell wall enclosing a lipid membrane. Gram-negative bacteria, such as <em>E. coli</em>, are more difficult to kill as they have an additional outer membrane that acts as an extra barrier. </p>
<p>Bacteria are able to bring in the things they need to survive through these cell surfaces. Antibiotics can hijack these entry routes, but bacteria can modify the cell wall, cell membrane and entry proteins to block antibiotic penetration.</p>
<p>For example, bacteria <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC149586/">increase the thickness</a> of the cell wall to resist antibiotics like vancomycin.</p>
<figure class="align-center ">
<img alt="Lab worker puts dropper into petri dish" src="https://images.theconversation.com/files/554684/original/file-20231019-21-kwo9mt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554684/original/file-20231019-21-kwo9mt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554684/original/file-20231019-21-kwo9mt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554684/original/file-20231019-21-kwo9mt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554684/original/file-20231019-21-kwo9mt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554684/original/file-20231019-21-kwo9mt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554684/original/file-20231019-21-kwo9mt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Bacteria are good at keeping antibiotics out.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/man-doing-a-sample-test-in-the-laboratory-4033148/">Edward Jenner/Pexels</a></span>
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<p><strong>2. Expel the antibiotic if it gets in</strong>. Bacteria have machinery known as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9032748/">efflux pumps</a>, which regurgitate unwanted molecules from within the bacteria. </p>
<p>Bacteria can alter the pump so it is more effective at removing the antibiotic, or they can simply make more pumps. </p>
<p>Resistance to macrolide antibiotics like erythromycin often involves <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1251515/">the production of more efflux pumps</a>.</p>
<p><strong>3) Alter the antibiotic target.</strong> Antibiotics, like most other drugs, generally work by blocking the function of important enzymes within the bacteria. They specifically bind to the target like a key in a lock. </p>
<p>If bacteria alter the target shape by changing the DNA/protein sequence, the antibiotic (key) can no longer bind to its target (lock). </p>
<p>Resistance to a class of antibiotics known as fluoroquinolones (which includes ciprofloxacin) often occurs due to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114060/">mutations of the enzyme targets</a>.</p>
<p><strong>4) Destroy or modify the antibiotic.</strong> Bacteria developed resistance to the original antibiotic, penicillin, by producing a protein that breaks apart the penicillin warhead. </p>
<p>These enzymes have evolved to keep pace with even the most recent new and improved penicillin-like antibiotics. </p>
<p>In response, drug developers <a href="https://www.drugs.com/drug-class/beta-lactamase-inhibitors.html">have created</a> molecules that specifically stop the enzyme from working, and dose these in combination with the antibiotic. </p>
<p>Another example of antibiotic modification is shown by resistance to a class of antibiotics called aminoglycosides. In this case, different types of enzymes <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4752126/">chemically modify</a> the structure of the aminoglycoside, such as the antibiotic tobramycin. Now, the key has been filed so that it no longer fits the lock.</p>
<figure class="align-center ">
<img alt="Person holds three antibiotic capsules" src="https://images.theconversation.com/files/554681/original/file-20231019-27-o3qlqf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554681/original/file-20231019-27-o3qlqf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554681/original/file-20231019-27-o3qlqf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554681/original/file-20231019-27-o3qlqf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554681/original/file-20231019-27-o3qlqf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554681/original/file-20231019-27-o3qlqf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554681/original/file-20231019-27-o3qlqf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Bacteria use multiple methods to attack antibiotics.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/three-capsules-on-persons-palm-U31rRVKYL_M">Mark Fletcher/Unsplash</a></span>
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<h2>Bacteria vs antibiotics</h2>
<p>While bacteria have developed mechanisms to resist antibiotics, these adaptations can come at a “fitness” cost. Bacteria may grow more slowly, or can be killed more easily by another antibiotic. </p>
<p>This has led to the concept of “<a href="https://academic.oup.com/mbe/article/39/12/msac257/6884036">collateral sensitivity</a>” to prevent or overcome resistance when treating patients, by using pairs of antibiotics. Resistance to the first antibiotic increases susceptibility to the second, and vice versa.</p>
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Read more:
<a href="https://theconversation.com/will-we-still-have-antibiotics-in-50-years-we-asked-7-global-experts-214950">Will we still have antibiotics in 50 years? We asked 7 global experts</a>
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<p>In some cases, the “fitness costs” (energy and materials expended to maintain resistance) mean that resistance genes can be present, but they are not activated until exposed to an antibiotic. This makes it difficult to predict bacterial resistance by just looking at their genetic makeup. </p>
<p>Bacteria may get “stronger,” but they are not yet invincible. We need to take action before antibiotic resistance returns us to a pre-antibiotic era.</p>
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<p><em>Read the other articles in The Conversation’s series on the dangers of antibiotic resistance <a href="https://theconversation.com/au/topics/the-dangers-of-antibiotic-resistance-146983">here</a>.</em></p><img src="https://counter.theconversation.com/content/213451/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Blaskovich receives funding from a range of government, not-for-profit and commercial organisations for research into antibiotic discovery and development. He is affiliated with AAMRNet (Australian Antimicrobial Resistance Network), an organisation promoting improved care and development of antibiotics and antibiotic alternatives.</span></em></p>Resistance arises when bacteria are exposed to levels of antibiotics that don’t immediately kill them. Here’s how.Mark Blaskovich, Professor, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2163442023-11-03T12:45:40Z2023-11-03T12:45:40ZVampire viruses prey on other viruses to replicate themselves − and may hold the key to new antiviral therapies<figure><img src="https://images.theconversation.com/files/557327/original/file-20231102-23-pcztem.png?ixlib=rb-1.1.0&rect=0%2C0%2C4306%2C1431&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The satellite virus MiniFlayer (purple) infects cells by attaching itself to the neck of its helper virus, MindFlayer (gray). </span> <span class="attribution"><a class="source" href="https://doi.org/10.1038/s41396-023-01548-0">Tagide deCarvalho</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Have you ever wondered whether the virus that gave you a nasty cold can catch one itself? It may comfort you to know that, yes, viruses can actually get sick. Even better, as karmic justice would have it, the culprits turn out to be other viruses.</p>
<p>Viruses can get sick in the sense that their normal function is impaired. When a virus enters a cell, it can either <a href="https://theconversation.com/viruses-may-be-watching-you-some-microbes-lie-in-wait-until-their-hosts-unknowingly-give-them-the-signal-to-start-multiplying-and-kill-them-189949">go dormant or start replicating right away</a>. When replicating, the virus essentially commandeers the molecular factory of the cell to make lots of copies of itself, then breaks out of the cell to set the new copies free.</p>
<p>Sometimes a virus enters a cell only to find that its new temporary dwelling is already home to another dormant virus. Surprise, surprise. What follows is a battle for control of the cell that can be won by either party. </p>
<p>But sometimes a virus will enter a cell to find a particularly nasty shock: a viral tenant waiting specifically to prey on the incoming virus.</p>
<p>I am a <a href="https://scholar.google.com/citations?user=T1I1sNAAAAAJ&hl=en">bioinformatician</a>, and <a href="https://erilllab.umbc.edu/">my laboratory</a> studies the evolution of viruses. We frequently run into “viruses of viruses,” but we recently discovered something new: a virus that <a href="https://doi.org/10.1038/s41396-023-01548-0">latches onto the neck of another virus</a>.</p>
<h2>A world of satellites</h2>
<p>Biologists have known of the existence of viruses that prey on other viruses – referred to as <a href="https://doi.org/10.1038/nrmicro2676">viral “satellites”</a> – for decades. In 1973, researchers studying bacteriophage P2, a virus that infects the gut bacterium <em>Escherichia coli</em>, found that this infection sometimes led to two different types of viruses emerging from the cell: <a href="https://doi.org/10.1016/0042-6822(73)90432-7">phage P2 and phage P4</a>.</p>
<p>Bacteriophage P4 is a temperate virus, meaning it can integrate into the chromosome of its host cell and lie dormant. When P2 infects a cell already harboring P4, the latent P4 quickly wakes up and <a href="https://doi.org/10.1128/mr.57.3.683-702.1993">uses the genetic instructions of P2</a> to make hundreds of its own small viral particles. The unsuspecting P2 is lucky to replicate a few times, if at all. In this case, biologists refer to P2 as a “helper” virus, because the satellite P4 needs P2’s genetic material to replicate and spread. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/YI3tsmFsrOg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bacteriophages are viruses that infect bacteria.</span></figcaption>
</figure>
<p>Subsequent research has shown that most bacterial species have a <a href="https://doi.org/10.1038/s41396-018-0156-3">diverse set of satellite-helper systems</a>, like that of P4-P2. But viral satellites are not limited to bacteria. Shortly after the largest known virus, mimivirus, was discovered in 2003, scientists also found its <a href="https://doi.org/10.1038/nature07218">satellite, which they named Sputnik</a>. <a href="https://doi.org/10.1016/0042-6822(81)90531-6">Plant viral satellites</a> that lurk in plant cells waiting for other viruses are also widespread and can have <a href="https://doi.org/10.1007/s11262-020-01806-9">important effects on crops</a>.</p>
<h2>Viral arms race</h2>
<p>Although researchers have found satellite-helper viral systems in pretty much <a href="https://doi.org/10.1016/j.coviro.2018.08.002">every domain of life</a>, their importance to biology remains underappreciated. Most obviously, viral satellites have a direct impact on their “helper” viruses, typically maiming them but <a href="https://doi.org/10.1016/j.coviro.2018.08.002">sometimes making them more efficient killers</a>. Yet that is probably the least of their contributions to biology. </p>
<p>Satellites and their helpers are also engaged in an <a href="https://doi.org/10.1371/journal.pgen.1005609">endless evolutionary arms race</a>. Satellites evolve new ways to exploit helpers and helpers evolve countermeasures to block them. Because both sides are viruses, the results of this internecine war necessarily include something of interest to people: antivirals.</p>
<p>Recent work indicates that many antiviral systems thought to have evolved in bacteria, like the CRISPR-Cas9 molecular scissors used in gene editing, may have <a href="https://doi.org/10.1093/nar/gkac845">originated in phages and their satellites</a>. Somewhat ironically, with their high turnover and mutation rates, helper viruses and their satellites turn out to be <a href="https://doi.org/10.1016/j.chom.2022.02.018">evolutionary hot spots for antiviral weaponry</a>. Trying to outsmart each other, satellite and helper viruses have come up with an unparalleled array of antiviral systems for researchers to exploit.</p>
<h2>MindFlayer and MiniFlayer</h2>
<p>Viral satellites have the potential to transform how researchers understand antiviral strategies, but there is still a lot to learn about them. In our recent work, my collaborators and I describe a satellite bacteriophage completely unlike previously known satellites, one that has evolved a <a href="https://doi.org/10.1038/s41396-023-01548-0">unique, spooky lifestyle</a>. </p>
<p><a href="https://phages.umbc.edu/">Undergraduate phage hunters</a> at the University of Maryland, Baltimore County isolated a <a href="https://phagesdb.org/phages/MiniFlayer/">satellite phage called MiniFlayer</a> from the soil bacterium <em>Streptomyces scabiei</em>. MiniFlayer was found in close association with a helper virus called <a href="https://phagesdb.org/phages/MindFlayer/">bacteriophage MindFlayer</a> that infects the <em>Streptomyces</em> bacterium. But further research revealed that MiniFlayer was no ordinary satellite.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/557149/original/file-20231101-28-nu795n.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1084%2C1097&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of a small round virus colored violet attached to the base of a larger round virus colored gray with a long tail" src="https://images.theconversation.com/files/557149/original/file-20231101-28-nu795n.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1084%2C1097&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557149/original/file-20231101-28-nu795n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=607&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557149/original/file-20231101-28-nu795n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=607&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557149/original/file-20231101-28-nu795n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=607&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557149/original/file-20231101-28-nu795n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=763&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557149/original/file-20231101-28-nu795n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=763&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557149/original/file-20231101-28-nu795n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=763&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This image shows <em>Streptomyces</em> satellite phage MiniFlayer (purple) attached to the neck of its helper virus, <em>Streptomyces</em> phage MindFlayer (gray).</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s41396-023-01548-0">Tagide deCarvalho</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>MiniFlayer is the first satellite phage known to have lost its ability to lie dormant. Not being able to lie in wait for your helper to enter the cell poses an important challenge to a satellite phage. If you need another virus to replicate, how do you guarantee that it makes it into the cell around the same time you do? </p>
<p>MiniFlayer addressed this challenge with evolutionary aplomb and horror-movie creativity. Instead of lying in wait, MiniFlayer has gone on the offensive. Borrowing from both “Dracula” and “Alien,” this satellite phage <a href="https://doi.org/10.1038/s41396-023-01548-0">evolved a short appendage</a> that allows it to latch onto its helper’s neck like a vampire. Together, the unwary helper and its passenger travel in search of a new host, where the viral drama will unfold again. We don’t yet know how MiniFlayer subdues its helper, or whether MindFlayer has evolved countermeasures.</p>
<p>If the recent pandemic has taught us anything, it is that our <a href="https://doi.org/10.1007/s00018-022-04635-1">supply of antivirals is rather limited</a>. Research on the complex, intertwined and at times predatory nature of viruses and their satellites, like the ability of MiniFlayer to attach to its helper’s neck, has the potential to open new avenues for antiviral therapy.</p><img src="https://counter.theconversation.com/content/216344/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ivan Erill receives funding from the US National Science Foundation. He is affiliated with the Universitat Autònoma de Barcelona. </span></em></p>Researchers discovered a satellite virus latching onto the neck of another virus called MindFlayer. Studying the viral arms race between similar viruses could lead to new ways to fight infections.Ivan Erill, Professor of Biological Sciences, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2134042023-09-28T15:52:22Z2023-09-28T15:52:22ZI’m a microbiologist and here’s what (and where) I never eat<figure><img src="https://images.theconversation.com/files/550869/original/file-20230928-17-d1ixap.jpg?ixlib=rb-1.1.0&rect=20%2C0%2C6689%2C4476&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/chafing-dish-food-1020163570">Alex Andrei/Shutterstock</a></span></figcaption></figure><p>Every year, around <a href="https://www.ukri.org/news/food-safety-network-to-tackle-9-billion-food-poisoning-challenge/#:%7E:text=Food%20poisoning%20key%20facts%3A,foodborne%20illness%20in%20the%20UK">2.4 million people</a> in the UK get food poisoning – mostly from viral or bacterial contamination. Most people recover <a href="https://www.nhsinform.scot/illnesses-and-conditions/infections-and-poisoning/food-poisoning/">within a few days without treatment</a>, but <a href="https://bmjopengastro.bmj.com/content/7/1/e000377">not all are that lucky</a>.</p>
<p>As a microbiologist, I’m probably more acutely aware of the risk of food-borne infections than most. Here are some of the things I look out for.</p>
<h2>Eating outdoors</h2>
<p>I rarely eat alfresco – whether picnics or barbecues – as the risk of food poisoning goes up when food is taken outdoors. </p>
<p>Keeping your hands clean when handling food is key to not getting sick, but how often do you find hot running water and soap in a park or on a beach? You can use alcohol hand gels (they’re better than nothing), but they don’t kill all germs. </p>
<p>Also, food tends to attract an array of flying and crawling critters, such as flies, wasps and ants, all of which can transfer germs, including <em>E coli</em>, <em>Salmonella</em> and <em>Listeria</em>, to your food. </p>
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Read more:
<a href="https://theconversation.com/a-fruit-fly-has-landed-in-your-wine-is-it-ok-to-drink-211847">A fruit fly has landed in your wine – is it OK to drink?</a>
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<p>Keeping perishable food cold and covered is essential as germs can double in numbers if food is allowed to warm up to 30°C for more than a few hours. For barbecues, meat needs to be thoroughly cooked, and a meat thermometer is a good investment to avoid food poisoning. Do not eat meat if its internal temperature is <a href="https://www.betterhealth.vic.gov.au/health/healthyliving/food-safety-outdoors">less than 70°C</a>. </p>
<h2>Buffets</h2>
<p>Knowing what food-related conditions bacteria prefer to grow in, I am very mindful of the microbiological safety of hot and cold buffet displays. </p>
<p>Indoors, food can be exposed to contamination from insects, dust and above all, people. Food poisoning is, therefore, an inevitable risk when dining at a <a href="https://www.fda.gov/food/buy-store-serve-safe-food/serving-safe-buffets">buffet</a>. </p>
<p>Contamination comes from buffet visitors touching food, and germs can be sprayed on to buffets from people sneezing or coughing close to the food. Even indoors, one must consider contamination by insects, such as flies or wasps, settling on the uncovered food. Also, germs may be deposited from the air, which is rich in bacteria, fungi and viruses. </p>
<p>I always look at the clock when I’m at a buffet as there is a <a href="https://www.cdc.gov/foodsafety/serving-food-safely.html">two-hour catering rule</a>: perishable food will become unsafe to eat within two hours if not kept covered and refrigerated. The problem is buffets tend to be laid out before you arrive, so it is difficult to tell if the platters of cooked meat, seafood, salads, desserts and appetisingly arranged fruit and vegetables will have been sitting for more than two hours when you come to eat them. </p>
<p>For hot buffets, such as those served at breakfast in hotels, I always avoid lukewarm food, as bacteria that cause food poisoning can grow quickly when food is <a href="https://www.fda.gov/food/buy-store-serve-safe-food/serving-safe-buffets">kept at less than 60°C</a>. Hot food should be served hot, that is at a temperature of at least 60°C. If there is any uncertainty about the safety of the food on offer, I reluctantly breakfast on freshly toasted bread and individually packaged marmalade. </p>
<h2>Oysters</h2>
<p>There are some foods I never eat, and raw shellfish, such as oysters, is one of them. This is because oysters are filter feeders and can concentrate germs, such as <em>Vibrio</em> and norovirus, in their tissue. </p>
<p>A <em>Vibrio</em>-contaminated oyster does not look, smell, or taste different, but can still make you very ill. The US Centers for Disease Control and Prevention estimates that about 80,000 people get <em>Vibrio</em> infections from raw oysters, and in the US alone 100 people <a href="https://www.cdc.gov/foodsafety/communication/oysters-and-vibriosis.html">die from vibriosis</a> each year.</p>
<p>It is also possible to pick up food poisoning from eating any raw shellfish (clams, mussels, whelks, cockles). I only eat shellfish that are well-cooked because heat effectively kills harmful germs. </p>
<h2>Bagged salads</h2>
<p>I never eat bagged salads, largely because one of my research areas is fresh salad safety. It has been found that bagged lettuce can contain food poisoning germs such as <em>E coli</em>, <em>Salmonella</em> and <em>Listeria</em>. </p>
<p>My research group <a href="https://journals.asm.org/doi/10.1128/aem.02416-16">has found</a> that these pathogens grow more than a thousand times better when given juices from salad leaves, even if the salad bag is refrigerated. Worryingly, the same germs use the salad juices to become more virulent, and so better at causing an infection.</p>
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<strong>
Read more:
<a href="https://theconversation.com/the-sniff-test-is-not-reliable-for-food-safety-heres-why-211808">The sniff test is not reliable for food safety – here's why</a>
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<p>For those salad lovers alarmed by this information, most bagged salads are safe if stored refrigerated, washed well before use (even ready-to-eat salad should be washed) and eaten as soon as possible after buying it. </p>
<figure class="align-center ">
<img alt="An open bag of lettuce." src="https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">If there are salad ‘juices’, throw it out.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/open-bag-salad-lettuce-carrots-white-528025258">Noel V. Baebler/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Cooking practices</h2>
<p>In terms of cooking practices, I have a list of dos and don’ts. </p>
<p>For perishable foods, I regularly check use-by dates, but if it is before the expiry date and the food package looks swollen, or when opened the food looks or smells different than expected, I throw it in the bin as it could be contaminated.</p>
<p>I never use the same chopping boards for raw and cooked foods, and washing my hands before and after handling food is instinctual. </p>
<p>One of my “never do” practices is reheating cooked rice. This is because uncooked rice can contain spores of <em>Bacillus cereus</em>, a food-poisoning germ. </p>
<p>Although the <em>Bacillus</em> cells are killed by cooking, the spores survive. If the rice is left to cool and sit at room temperature, <a href="https://www.nhs.uk/common-health-questions/food-and-diet/can-reheating-rice-cause-food-poisoning/#:%7E:text=Yes%2C%20you%20can%20get%20food,been%20stored%20before%20it%E2%80%99s%20reheated">the spores grow into bacteria</a>, which will increase in numbers quickly as rice is a good <em>Bacillus</em> culture medium when at room temperature. </p>
<p>The rice-cultured <em>Bacillus</em> can produce toxins that, within a few hours of ingestion, can cause vomiting and diarrhoea lasting up to 24 hours.</p>
<h2>Dining out</h2>
<p>I find that having a high level of food safety awareness causes me to be first in line for buffets, to be cautious about eating from breakfast bars, and to watch the clock for how often perishable food is replaced. I never collect “doggy bags” of food leftovers (they have usually exceeded the two-hour time limit), even if they really are intended for a pet. </p>
<p>The benefits of being a microbiologist are that we know how to avoid food poisoning and, in return, people have confidence our cooking is very safe to eat.</p><img src="https://counter.theconversation.com/content/213404/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Primrose Freestone has previously received funding from the BBSRC for her salad research work..</span></em></p>You’ll never look at bagged lettuce the same way again.Primrose Freestone, Senior Lecturer in Clinical Microbiology, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2140482023-09-28T12:28:11Z2023-09-28T12:28:11ZYour microbes live on after you die − a microbiologist explains how your necrobiome recycles your body to nourish new life<figure><img src="https://images.theconversation.com/files/550423/original/file-20230926-27-qpnpj4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1794%2C1668&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">After you die, bacteria harvest your body for the nutrients that help push daisies.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/embroidery-skull-and-roses-grapes-humming-royalty-free-illustration/931298520">Matriyoshka/iStock via Getty Images Plus</a></span></figcaption></figure><p>Each human body contains a <a href="https://www.hmpdacc.org/overview/">complex community of trillions of microorganisms</a> that are important for your health while you’re alive. These <a href="https://open.oregonstate.education/generalmicrobiology/chapter/microbial-symbioses/">microbial symbionts</a> help you digest food, produce essential vitamins, protect you from infection and serve many other critical functions. In turn, the microbes, which are mostly concentrated in your gut, get to live in a relatively stable, warm environment with a steady supply of food.</p>
<p>But what happens to these symbiotic allies after you die? </p>
<p>As an <a href="https://scholar.google.com/citations?user=U_xOnjEAAAAJ&hl=en">environmental microbiologist</a> who studies <a href="https://doi.org/10.1093/femsec/fiad006">the necrobiome</a> – the microbes that live in, on and around a decomposing body – I’ve been curious about our postmortem microbial legacy. You might assume that your microbes die with you – once your body breaks down and your microbes are flushed into the environment, they won’t survive out in the real world. </p>
<p>In our September 2023 study, my research team and I share evidence that not only do your microbes continue to live on after you die, they actually play an important role in <a href="https://doi.org/10.1186/s13717-023-00451-y">recycling your body</a> so that new life can flourish.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/c_ZRZkU-FEw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Your microbes accompany you from cradle to grave.</span></figcaption>
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<h2>Microbial life after death</h2>
<p>When you die, your heart stops circulating the blood that has carried oxygen throughout your body. Cells deprived of oxygen start digesting themselves in a <a href="https://en.wikipedia.org/wiki/Autolysis_(biology)">process called autolysis</a>. Enzymes in those cells – which normally digest carbohydrates, proteins and fats for energy or growth in a controlled way – start to work on the membranes, proteins, DNA and other components that make up the cells. </p>
<p>The products of this cellular breakdown make excellent food for your symbiotic bacteria, and without your immune system to keep them in check and a steady supply of food from your digestive system, they turn to this new source of nutrition. </p>
<p><a href="https://doi.org/10.7717/peerj.3437">Gut bacteria</a>, especially a class of microbes called <a href="https://doi.org/10.3389/fmicb.2017.02096"><em>Clostridia</em></a>, <a href="https://doi.org/10.1016/j.forsciint.2016.03.019">spread through your organs</a> and digest you from the inside out in a process called <a href="https://www.ncbi.nlm.nih.gov/books/NBK539741/">putrefaction</a>. Without oxygen inside the body, your anaerobic bacteria rely on energy-producing processes that don’t require oxygen, such as fermentation. These create the distinctly odorous-gases signature to decomposition.</p>
<p>From an <a href="https://doi.org/10.1016/j.meegid.2017.09.006">evolutionary standpoint</a>, it makes sense that your microbes would have evolved ways to adapt to a dying body. Like rats on a sinking ship, your bacteria will soon have to abandon their host and survive out in the world long enough to find a new host to colonize. Taking advantage of the carbon and nutrients of your body allows them to increase their numbers. A bigger population means a higher probability that at least a few will survive out in the harsher environment and successfully find a new body.</p>
<h2>A microbial invasion</h2>
<p>If you’re buried in the ground, your microbes are flushed into the soil along with a soup of decomposition fluids as your body breaks down. They’re entering an entirely new environment and encountering a whole new microbial community in the soil.</p>
<p>The <a href="https://doi.org/10.1016/j.tree.2015.06.004">mixing or coalescence</a> of two distinct microbial communities happens frequently in nature. Coalescence happens when the roots of two plants grow together, when wastewater is emptied into a river or even when two people kiss.</p>
<p>The outcome of mixing – which community dominates and which microbes are active – depends on several factors, such as how much environmental change the microbes experience and who was there first. Your microbes are adapted to the stable, warm environment inside your body where they receive a steady supply of food. In contrast, soil is a particularly <a href="https://doi.org/10.1016/B978-0-12-820202-9.00002-2">harsh place to live</a> – it’s a highly variable environment with steep chemical and physical gradients and big swings in temperature, moisture and nutrients. Furthermore, soil already hosts an exceptionally diverse microbial community full of decomposers that are well adapted to that environment and would presumably outcompete any newcomers. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of Clostridium septicum" src="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=501&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=501&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=501&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=629&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=629&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=629&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Clostridium septicum</em> is one species of bacteria involved in putrefaction.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2n1hVng">Joseph E. Rubin/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>It’s easy to assume that your microbes will die off once they are outside your body. However, my research team’s previous studies have shown that the DNA signatures of host-associated microbes can be detected in the soil below a decomposing body, <a href="https://doi.org/10.1371/journal.pone.0130201">on the soil surface</a> and <a href="https://doi.org/10.1371/journal.pone.0208845">in graves</a> for months or years after the soft tissues of the body have decomposed. This raised the question of whether these microbes are still alive and active or if they are merely in a dormant state waiting for the next host.</p>
<p>Our newest study suggests that your microbes are not only living in the soil but also <a href="https://doi.org/10.1186/s13717-023-00451-y">cooperating with native soil microbes</a> to help decompose your body. In the lab, we showed that mixing soil and decomposition fluids filled with host-associated microbes increased decomposition rates beyond that of the soil communities alone.</p>
<p>We also found that host-associated microbes <a href="https://doi.org/10.1186/s13717-023-00451-y">enhanced nitrogen cycling</a>. Nitrogen is an essential nutrient for life, but most of the nitrogen on Earth is tied up as atmospheric gas that organisms can’t use. Decomposers play a critical role recycling organic forms of nitrogen such as proteins <a href="https://doi.org/10.1016/j.soilbio.2018.03.005">into inorganic forms</a> such as ammonium and nitrate that microbes and plants can use. </p>
<p>Our new findings suggest that our microbes are likely <a href="https://doi.org/10.1186/s13717-023-00451-y">playing a part</a> in this recycling process by converting large nitrogen-containing molecules like proteins and nucleic acids into ammonium. Nitrifying microbes in the soil can then convert the ammonium into nitrate. </p>
<h2>Next generation of life</h2>
<p>The recycling of nutrients from detritus, or nonliving organic matter, is a <a href="https://doi.org/10.2307/1930126">core process in all ecosystems</a>. In terrestrial ecosystems, decomposition of dead animals, or carrion, <a href="https://doi.org/10.1007/s00442-012-2460-3">fuels biodiversity</a> and is an important <a href="https://doi.org/10.1002/ece3.7542">link in food webs</a>.</p>
<p>Living animals are a bottleneck for the carbon and nutrient cycles of an ecosystem. They slowly accumulate nutrients and carbon from large areas of the landscape throughout their lives then deposit it all at once in a small, localized spot when they die. One dead animal can support a whole pop-up food web of <a href="https://doi.org/10.1093/femsec/fiad006">microbes</a>, <a href="https://doi.org/10.1371/journal.pone.0241777">soil fauna</a> and <a href="https://doi.org/10.1007/978-3-642-88448-1_6">arthropods</a> that make their living off carcasses. </p>
<p><a href="https://theconversation.com/life-after-death-how-insects-rise-from-the-dead-and-transform-corpses-into-skeletons-148847">Insect</a> and <a href="https://doi.org/10.1890/09-0292.1">animal scavengers</a> help further redistribute nutrients in the ecosystem. Decomposer microbes convert the concentrated pools of nutrient-rich organic molecules from our bodies into <a href="https://doi.org/10.1371/journal.pone.0287094">smaller, more bioavailable forms</a> that other organisms can use to support new life. It’s not uncommon to see <a href="https://doi.org/10.1002/ecs2.1537">plant life flourishing near a decomposing animal</a>, visible evidence that nutrients in bodies are being recycled back into the ecosystem.</p>
<p>That our own microbes play an important role in this cycle is one microscopic way we live on after death.</p><img src="https://counter.theconversation.com/content/214048/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer DeBruyn receives funding from the United States Department of Agriculture, National Science Foundation, Department of Justice, and Defense Advanced Research Projects Agency.</span></em></p>With the help of the microbes that once played an essential role in keeping you alive, the building blocks of your body go on to become a part of other living things.Jennifer DeBruyn, Professor of Environmental Microbiology, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2136212023-09-25T12:21:07Z2023-09-25T12:21:07ZFlesh-eating bacteria infections are on the rise in the US − a microbiologist explains how to protect yourself<figure><img src="https://images.theconversation.com/files/549431/original/file-20230920-17-vywy11.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1576%2C1080&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_Vibrio vulnificus_ infections are spreading across the U.S. because of climate change.</span> <span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=7812">CDC/Janice Haney Carr</a></span></figcaption></figure><p>Flesh-eating bacteria sounds like the premise of a bad horror movie, but it’s a growing – and potentially fatal – threat to people.</p>
<p>In September 2023, the Centers for Disease Control and Prevention <a href="https://emergency.cdc.gov/han/2023/han00497.asp">issued a health advisory</a> alerting doctors and public health officials of an increase in flesh-eating bacteria cases that can cause serious wound infections. </p>
<p><a href="https://medicine.iu.edu/faculty/13502/sullivan-william">I’m a professor</a> at the Indiana University School of Medicine, where <a href="https://www.sullivanlab.com/">my laboratory</a> studies <a href="https://scholar.google.com/citations?user=mN6ZaFkAAAAJ&hl=en">microbiology and infectious disease</a>. Here’s why the CDC is so concerned about this deadly infection – and ways to avoid contracting it.</p>
<h2>What does ‘flesh-eating’ mean?</h2>
<p>There are several types of bacteria that can infect open wounds and cause a rare condition called <a href="https://doi.org/10.1097%2F01.NURSE.0000694752.85118.62">necrotizing fasciitis</a>. These bacteria do not merely damage the surface of the skin – they release toxins that destroy the underlying tissue, including muscles, nerves and blood vessels. Once the bacteria reach the bloodstream, they gain ready access to additional tissues and organ systems. If left untreated, necrotizing fasciitis can be fatal, sometimes within 48 hours.</p>
<p>The bacterial species <a href="https://www.cdc.gov/groupastrep/index.html">group A <em>Streptococcus</em></a>, or group A strep, is the most common culprit behind necrotizing fasciitis. But the CDC’s latest warning points to an additional suspect, a type of bacteria called <a href="https://www.cdc.gov/vibrio/wounds.html"><em>Vibrio vulnificus</em></a>. There are only <a href="https://emergency.cdc.gov/han/2023/han00497.asp">150 to 200 cases</a> of <em>Vibrio vulnificus</em> in the U.S. each year, but the mortality rate is high, with 1 in 5 people succumbing to the infection.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/FZrb8ttsfg8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Climate change may be driving the rise in flesh-eating bacteria infections in the U.S.</span></figcaption>
</figure>
<h2>How do you catch flesh-eating bacteria?</h2>
<p><em>Vibrio vulnificus</em> primarily lives in warm seawater but can also be found in brackish water – areas where the ocean mixes with freshwater. Most infections in the U.S. occur in the <a href="https://doi.org/10.1001/jama.2023.0174">warmer months, between May and October</a>. People who swim, fish or wade in these bodies of water can contract the bacteria through an open wound or sore.</p>
<p><em>Vibrio vulnificus</em> can also get into seafood harvested from these waters, especially shellfish like oysters. Eating such foods raw or undercooked can lead to <a href="https://www.cdc.gov/vibrio/food.html">food poisoning</a>, and handling them while having an open wound can provide an entry point for the bacteria to cause necrotizing fasciitis. In the U.S., <em>Vibrio vulnificus</em> is a leading cause of <a href="https://doi.org/10.3389/fmicb.2017.00997">seafood-associated fatality</a>.</p>
<h2>Why are flesh-eating bacteria infections rising?</h2>
<p><em>Vibrio vulnificus</em> is found in warm coastal waters around the world. In the U.S., this includes southern Gulf Coast states. But rising ocean temperatures due to global warming are creating new habitats for this type of bacteria, which can now be found along the East Coast as far north as <a href="https://emergency.cdc.gov/han/2023/han00497.asp">New York and Connecticut</a>. A <a href="https://doi.org/10.1038/s41598-023-28247-2">recent study</a> noted that <em>Vibrio vulnificus</em> wound infections increased eightfold between 1988 and 2018 in the eastern U.S. </p>
<p><a href="https://www.pbs.org/newshour/health/flesh-eating-bacteria-on-the-rise-in-florida-following-hurricane-ian">Climate change</a> is also fueling stronger hurricanes and storm surges, which have been associated with spikes in flesh-eating bacteria infection cases.</p>
<p>Aside from increasing water temperatures, the number of people who are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2762295/">most vulnerable to severe infection</a>, including those <a href="https://theconversation.com/global-diabetes-cases-on-pace-to-soar-to-1-3-billion-people-in-the-next-3-decades-new-study-finds-208832">with diabetes</a> and those taking medications that suppress immunity, is on the rise.</p>
<h2>What are symptoms of necrotizing fasciitis? How is it treated?</h2>
<p><a href="https://www.cdc.gov/groupastrep/diseases-public/necrotizing-fasciitis.html#symptoms">Early symptoms</a> of an infected wound include fever, redness, intense pain or swelling at the site of injury. If you have these symptoms, seek medical attention without delay. Necrotizing fasciitis can <a href="https://www.cdc.gov/groupastrep/diseases-public/necrotizing-fasciitis.html#symptoms">progress quickly</a>, producing ulcers, blisters, skin discoloration and pus.</p>
<p><a href="https://www.cdc.gov/groupastrep/diseases-public/necrotizing-fasciitis.html">Treating flesh-eating bacteria</a> is a race against time. Clinicians administer antibiotics directly into the bloodstream to kill the bacteria. In many cases, damaged tissue needs to be surgically removed to stop the rapid spread of the infection. This sometimes <a href="https://pubmed.ncbi.nlm.nih.gov/33623768/">results in amputation</a> of affected limbs.</p>
<p>Researchers are concerned that an increasing number of cases are becoming impossible to treat because <em>Vibrio vulnificus</em> has evolved <a href="https://doi.org/10.3389/fmicb.2017.00997">resistance to certain antibiotics</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/pGxIXTvSpTM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Necrotizing fasciitis is rare but deadly.</span></figcaption>
</figure>
<h2>How do I protect myself?</h2>
<p>The CDC offers several recommendations to help <a href="https://www.cdc.gov/vibrio/wounds.html">prevent infection</a>. </p>
<p>People who have a fresh cut, including a new piercing or tattoo, are advised to stay out of water that could be home to <em>Vibrio vulnificus</em>. Otherwise, the wound should be completely covered with a waterproof bandage. </p>
<p>People with an open wound should also avoid handling raw seafood or fish. Wounds that occur while fishing, preparing seafood or swimming should be washed immediately and thoroughly with soap and water.</p>
<p>Anyone can contract necrotizing fasciitis, but people with weakened immune systems are <a href="https://doi.org/10.1001/jama.2023.0174">most susceptible to severe disease</a>. This includes people taking immunosuppressive medications or those who have pre-existing conditions such as liver disease, cancer, HIV or diabetes.</p>
<p>It is important to bear in mind that necrotizing fasciitis presently <a href="https://doi.org/10.1097%2F01.NURSE.0000694752.85118.62">remains very rare</a>. But given its severity, it is beneficial to stay informed.</p><img src="https://counter.theconversation.com/content/213621/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bill Sullivan receives funding from the National Institutes of Health.</span></em></p>Warmer ocean waters are fueling the spread of the bacteria Vibrio vulnificus. Infections can lead to a rare but fatal condition called necrotizing fasciitis.Bill Sullivan, Professor of Pharmacology & Toxicology, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2092712023-07-26T11:09:48Z2023-07-26T11:09:48ZAustralian ant honey inhibits tough pathogens, new research shows<figure><img src="https://images.theconversation.com/files/539207/original/file-20230725-19-ukl2g.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4031%2C3024&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Danny Ulrich and Andrew Dong</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The medicinal value and potent antimicrobial activity of <a href="https://theconversation.com/science-or-snake-oil-is-manuka-honey-really-a-superfood-for-treating-colds-allergies-and-infections-78400">honey</a> has been a topic of considerable interest in recent years, particularly in light of the alarming rise in antibiotic resistance. </p>
<p>While most honey comes from honey bees (<em>Apis mellifera</em>), <a href="https://theconversation.com/wasps-aphids-and-ants-the-other-honey-makers-102838">other insects</a> such as stingless bees, wasps and even ants can produce honey-like products from plant nectar. </p>
<p>One of these insects is the honeypot ant <em>Camponotus inflatus</em>, found throughout the central desert region of Australia. We set out to determine whether its honey might be medically useful.</p>
<p>Our results, <a href="https://doi.org/10.7717/peerj.15645">published in PeerJ</a>, show the honey has powerful anti-microbial effects, particularly against certain heat-tolerant yeasts and moulds which resist most current antifungal drugs.</p>
<h2>Pots of gold</h2>
<p>Honeypot ants are social ant species that develop large nests in the soil. Within these colonies, certain worker ants known as “repletes” serve as living food stores. </p>
<p>The repletes are fed by other members of the colony, who forage for nectar and honeydew in the environment. The repletes accumulate a golden honey-like substance in their flexible abdomens. </p>
<p>The repletes become so engorged with honey they are rendered almost immobile. They hang together from the ceiling of the nest, forming a sort of ant pantry. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/539249/original/file-20230725-25-6avf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539249/original/file-20230725-25-6avf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539249/original/file-20230725-25-6avf8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539249/original/file-20230725-25-6avf8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539249/original/file-20230725-25-6avf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539249/original/file-20230725-25-6avf8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539249/original/file-20230725-25-6avf8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Honeypot ant ‘repletes’ store honey for the nest.</span>
<span class="attribution"><span class="source">Andrew Dong</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In times of need, other worker ants visit the repletes and stroke their antennae. The repletes cough up some honey in response, and the other workers then distribute it throughout the colony.</p>
<p>Most honeypot ants live in very dry environments. Their unusual lifestyle has been so successful it has <a href="https://www.tandfonline.com/doi/abs/10.1080/03949370.1991.10721919">evolved multiple times</a>.</p>
<h2>Honeypot ants in First Nations culture</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/539244/original/file-20230725-28-emh9ho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/539244/original/file-20230725-28-emh9ho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/539244/original/file-20230725-28-emh9ho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=645&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539244/original/file-20230725-28-emh9ho.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=645&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539244/original/file-20230725-28-emh9ho.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=645&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539244/original/file-20230725-28-emh9ho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=811&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539244/original/file-20230725-28-emh9ho.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=811&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539244/original/file-20230725-28-emh9ho.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=811&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Digging for honeypot ants.</span>
<span class="attribution"><span class="source">Danny Ulrich</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In Australia, <em>Camponotus inflatus</em> is found throughout the central desert region and holds cultural and nutritional significance to local Indigenous people. </p>
<p>Danny Ulrich of the Tjupan language group, operator of <a href="https://goldfieldshoneyanttours.com.au/">Goldfields Honey Ant Tours</a> in Kalgoorlie, Western Australia, says</p>
<blockquote>
<p>For our people, honey ants are more than just a food source. Digging for them is a very enjoyable way of life. It’s a way of bringing the family together, to connect with each other and nature. </p>
</blockquote>
<p>There are also reports of traditional use of honeypot ant honey for treating ailments like colds and sore throats, and possibly as a topical ointment to help keep infections at bay, suggesting potential antimicrobial properties.</p>
<h2>Not your usual honey activity</h2>
<p>To investigate further, we obtained honeypot ant repletes from Goldfields Honey Ant Tours, collected and pooled the honey from the ants and tested its ability to inhibit various pathogenic bacteria, yeasts and moulds. </p>
<p>We compared this to two well-studied bee honeys with anti-microbial properties: manuka honey from New Zealand, and jarrah honey from Western Australia. </p>
<p>Our <a href="https://doi.org/10.7717/peerj.15645">results</a> revealed striking differences between the honeypot ant honey and the bee honeys. </p>
<p>Both bee honeys showed broad activity and were able to inhibit every pathogen tested at similar levels. However, the honeypot ant honey showed remarkable potency against certain microbes, but little against others.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/science-or-snake-oil-is-manuka-honey-really-a-superfood-for-treating-colds-allergies-and-infections-78400">Science or Snake Oil: is manuka honey really a 'superfood' for treating colds, allergies and infections?</a>
</strong>
</em>
</p>
<hr>
<p>Important factors that contribute to the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0023643820313682">antimicrobial power</a> of bee honey are its high sugar and low water content, which sucks the water out of microbial invaders.</p>
<p>We found honeypot ant honey to have a much higher moisture content than the bee honeys, however, putting it in a range that could support the growth of some microorganisms. </p>
<p>Most bee honeys also contain enzymes that produce hydrogen peroxide, a known antimicrobial compound. However, honeypot ant honey retained most of its activity even after we removed all the hydrogen peroxide. </p>
<p>Finally, some honeys contain antimicrobial proteins and peptides that are derived from the honey bee. These can be destroyed by heat, and when we heated the honeypot ant honey to 90°C for 10 minutes it lost most of its antimicrobial activity. </p>
<p>We therefore think this unique antimicrobial activity is likely due to proteins or peptides, and these are probably derived from the honeypot ant.</p>
<h2>Evolution of antimicrobial activity in the insect world</h2>
<p>In the natural environment, animals, plants, and the products they make are exposed to a huge range of microorganisms looking for their next meal. Sweet, nutritious honey is an enticing food source for these microbial scavengers and must be vigorously protected, both to prevent its spoilage and to stop invasion of the hive or nest by rapidly growing moulds. </p>
<p>Intriguingly, we found honeypot ant honey was particularly effective against some pathogens we consider to be quite “tough”. These pathogens are well adapted to living in soils and dry conditions, and can also cause very serious infections in people with severely weakened immune systems. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/wasps-aphids-and-ants-the-other-honey-makers-102838">Wasps, aphids and ants: the other honey makers</a>
</strong>
</em>
</p>
<hr>
<p>In particular, the ant honey was able to inhibit heat-tolerant yeasts and moulds that are likely to be present in the honey ant nest and surrounding environment. Importantly, these can be very difficult to kill with most currently available <a href="https://www.mdpi.com/2218-1989/10/3/106">antifungal drugs</a>.</p>
<p>We suggest the evolutionary pressure imposed by these soil microorganisms has resulted in the potent, selective antimicrobial activity of honeypot ant honey.</p>
<h2>Science catches up with Indigenous knowledge</h2>
<p>Our results clearly support the medicinal use of honeypot ant honey by Australian Indigenous communities and provide a new understanding of the intricate relationship between honeypot ants, their environment, and the remarkable antimicrobial activity exhibited by their honey. </p>
<p>Due to the cultural significance of the ants, and challenges with rearing them at a commercial scale, it is not feasible to domesticate honeypot ants for honey production. </p>
<p>However, honeypot ant honey may provide valuable insights for the development of useful new antimicrobial peptides. These may help expand our arsenal of effective antibacterial and antifungal treatments, which are increasingly needed to combat emerging challenges in healthcare.</p><img src="https://counter.theconversation.com/content/209271/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dee Carter has received funding to support work on honey bee honey from The Rural Industries Research and Development Corporation, AgriFutures, the Australian Research Council (Linkage program), and the NSW Government under the Bushfire Industry Recovery Package.</span></em></p><p class="fine-print"><em><span>Danny Ulrich is the operator of Goldfields Honey Ant Tours.</span></em></p><p class="fine-print"><em><span>Kenya Fernandes conducts research on honey bees and medicinal honey supported by the NSW Government under the Bushfire Industry Recovery Package.</span></em></p><p class="fine-print"><em><span>Nural Cokcetin has received funding to support research on honey bees and medicinal honey from AgriFutures Australia and the NSW Government under the Bushfire Industry Recovery Package. She is a member of the NSW Apiarists' Association. </span></em></p><p class="fine-print"><em><span>Andrew Dong does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Experiments show honey from Australian desert ants has potent antimicrobial power.Dee Carter, Professor of Microbiology, University of SydneyAndrew Dong, Research Affiliate, Microbiology, University of SydneyDanny Ulrich, Operator, Goldfields Honey Ant Tours, Indigenous KnowledgeKenya Fernandes, Postdoctoral Researcher, University of SydneyNural Cokcetin, Research scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2060452023-07-05T12:23:01Z2023-07-05T12:23:01Z‘E. coli’ is one of the most widely studied organisms – and that may be a problem for both science and medicine<figure><img src="https://images.theconversation.com/files/534368/original/file-20230627-19-w2lrsx.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2133%2C1404&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_E. coli_ as a model organism helped researchers better understand how DNA works.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/researcher-with-e-coli-bacteria-royalty-free-image/521677434">Ed Horowitz Photography/The Image Bank via Getty Images</a></span></figcaption></figure><p>In 1857, a young pediatrician named <a href="https://doi.org/10.1038/nrmicro1810">Theodor Escherich</a> discovered what may very well be the most well-studied organism today. The rod-shaped bacterium named <em>Escherichia coli</em>, better known as <em>E. coli</em>, is a very common microbe residing in your gut. It’s also the workhorse of early molecular biology.</p>
<p>Luck likely played a role in its rise in popularity among scientists. Even under 19th-century lab conditions, where sterilization techniques were not perfect and little was known about what food bacteria need to survive, this microbe was easy to cultivate and grow quickly. It can <a href="https://doi.org/10.1098/rspb.2018.0789">replicate in under 20 minutes</a> and can use a variety of <a href="https://doi.org/10.1186/s12918-014-0133-z">carbon sources for energy</a>. </p>
<p>As the first species to have its <a href="https://doi.org/10.1128/jb.29.2.205-213.1935">physiology thoroughly explored</a>, <em>E. coli</em> has contributed fundamental knowledge to the fields of microbiology, molecular genetics and biochemistry, including how DNA replicates, how genes create proteins and how bacteria share genetic material among themselves – a huge <a href="https://theconversation.com/antibiotic-resistance-is-at-a-crisis-point-government-support-for-academia-and-big-pharma-to-find-new-drugs-could-help-defeat-superbugs-169443">cause of antibiotic resistance</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of E. coli structure" src="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=458&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=458&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=458&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>E. coli</em> is a rod-shaped bacterium with flagella that help it move.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/coli-bacteria-micro-biological-vector-royalty-free-illustration/957344970">VectorMine/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>However, the favored use of <em>E. coli</em> in the lab has also <a href="https://doi.org/10.1529/biophysj.107.104398">led to oversimplifications</a> in the world of microbiology, distracting researchers from the thousands of other bacterial species that <a href="https://doi.org/10.1073/pnas.1707009114">remain understudied</a>. </p>
<p>As <a href="https://doerr.wicmb.cornell.edu/current-lab-members/">microbiologists</a> <a href="https://scholar.google.com/citations?user=yYroRg8AAAAJ&hl=en">studying the</a> inner mechanisms of <a href="https://theconversation.com/looming-behind-antibiotic-resistance-is-another-bacterial-threat-antibiotic-tolerance-200226">antibiotic tolerance</a>, we and colleagues in <a href="https://doerr.wicmb.cornell.edu/">our lab</a> examine bacterial species that physiologically differ from <em>E. coli</em> in hopes of expanding the existing pool of knowledge within microbiology. For instance, drugs like penicillin fall into a class of antibiotics that target the outer defenses of the bacteria. We found that while <em>E. coli</em> succumbs to this attack, species like <em>Vibrio</em> or <em>Klebsiella</em> can <a href="https://theconversation.com/looming-behind-antibiotic-resistance-is-another-bacterial-threat-antibiotic-tolerance-200226">tolerate it and survive</a>. </p>
<p>A one-size-fits-all approach may have worked in the past, but embracing the true diversity of microbes could help scientists better fight the rise of antibiotic resistance.</p>
<h2>Scientific good of <em>E. coli</em></h2>
<p>Researchers worked out the very foundations of life using <em>E. coli</em>. The significance of this bacterium for the field of biology is probably best captured by the biochemist <a href="https://www.nobelprize.org/prizes/medicine/1965/monod/facts/">Jacques Monod</a>, who famously said, “What is true for <em>E. coli</em> is true for the elephant.” </p>
<p>Because researchers were able to watch regions of <a href="https://doi.org/10.1038/158558a0"><em>E. coli</em>‘s DNA become mobile</a>, allowing bacteria to transfer DNA among one another in a process called conjugation, scientists learned to manipulate this process to genetically alter organisms and study the effects of different genes. </p>
<p><em>E. coli</em> helped reveal that <a href="https://doi.org/10.1101/SQB.1963.028.01.011">bacterial chromosomes are circular</a> and that <a href="https://doi.org/10.1016/S0022-2836(59)80045-0">manipulating a specific enzyme</a> can allow scientists to easily clone parts of the bacterial genome. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of E. coli, colored orange" src="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=516&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=516&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=516&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=648&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=648&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=648&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">While <em>E. coli</em> are common residents in your gut, certain strains can cause serious infections.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/coli-sem-royalty-free-image/1414386430">Steve Gschmeissner/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p><em>E. coli</em> also opened doors to using a type of <a href="https://theconversation.com/viruses-are-both-the-villains-and-heroes-of-life-as-we-know-it-169131">bacterial viruses called phages</a> as an <a href="https://doi.org/10.1085/jgp.22.3.365">alternative to antibiotics</a>. </p>
<p>Widely available knowledge about and methods to study <em>E. coli</em> led to its prominence in academic and commercial research and drug production. In 2015, <a href="https://doi.org/10.4014/jmb.1412.12079">nearly 30% of proteins used as treatments</a> for a wide range of diseases like hepatitis C and multiple sclerosis were derived from <em>E. coli</em>.</p>
<h2>Model organism drawbacks</h2>
<p><em>E. coli</em>’s track record has solidified its place in the lab as a <a href="https://doi.org/10.1007/978-1-4419-9863-7_76">model organism</a>. Model organisms are nonhuman species researchers use to study biology, with the expectation that the findings can be applied to other species like humans. Species are often chosen for their ease of maintenance, quick life cycles and overall cost-effectiveness. </p>
<p>However, model organisms have their drawbacks. Some researchers have argued that drawing parallels across species can <a href="https://theconversation.com/expanding-alzheimers-research-with-primates-could-overcome-the-problem-with-treatments-that-show-promise-in-mice-but-dont-help-humans-188207">sometimes fall short</a>, leading to assumptions about more complex species that may not be true.</p>
<p>Additionally, study findings using nonmodel organisms are often less visible in the broader scientific community, since many researchers focus on organisms with known and defined traits. This bias results in a shadow space where progress is not immediately incorporated into broader scientific knowledge, which can slow down research that actually covers a range from bacteria to elephants.</p>
<h2>ESKAPE pathogens don’t include <em>E. coli</em></h2>
<p>Model organisms are not perfect, and <em>E. coli</em> may not be an effective species to use to study many human bacterial infections. Focusing research on this microbe limits the exploration of how other bacteria infiltrate and infect human hosts. While some <a href="https://doi.org/10.1038/nrmicro818">strains of <em>E. coli</em> can be deadly</a>, they are not the only worrisome pathogens today. </p>
<p><a href="https://doi.org/10.1128/cmr.00181-19">ESKAPE pathogens</a>, a group of bacteria that are highly resistant to antibiotics, pose a massive global health threat because they can quickly evolve traits that allow them to evade immune systems and available treatments. Species within ESKAPE, such as <em>Klebsiella pneumoniae</em> and <em>E. cloacae</em>, are able to resist multiple drugs and <a href="https://doi.org/10.1128/aac.00756-19">exhibit physical characteristics</a> that <em>E. coli</em> does not, such as the ability to remove their cell wall and evade certain drugs.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/EkyAuG9RSSU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Antibiotic-resistant bacteria are a major global health threat.</span></figcaption>
</figure>
<p>Our lab is studying the unique traits that allow ESKAPE pathogens to survive antibiotics – traits we would not have known about if we used only <em>E. coli</em> as a model organism in our research.</p>
<p>With the many basics of fundamental bacterial cell and molecular biology covered thanks to <em>E. coli</em>, it may be time for researchers to turn toward the new pathogens wreaking havoc on society. Model organisms are wondrous tools, but they have limited power to allow findings to be extrapolated to other organisms. Better understanding the underpinnings of bacterial infections and antibiotics for a given disease requires studying the specific organism.</p><img src="https://counter.theconversation.com/content/206045/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Megan Keller receives funding from National Science Foundation. </span></em></p><p class="fine-print"><em><span>Tobias Dörr receives funding from National Institutes of Health. </span></em></p>Researchers uncovered the foundations of biology by using E. coli as a model organism. But over-reliance on this microbe can lead to knowledge blind spots with implications for antibiotic resistance.Megan Keller, Ph.D. Candidate in Microbiology, Cornell UniversityTobias Dörr, Associate Professor of Microbiology, Cornell UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1990742023-06-26T12:21:11Z2023-06-26T12:21:11ZDo you crush microbes when you step on them?<figure><img src="https://images.theconversation.com/files/528637/original/file-20230526-23155-iczgi5.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2122%2C1410&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">You don't need to watch where you step when it comes to bacteria.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/woman-walking-in-park-on-sunny-day-royalty-free-image/1326118536">Westend61/Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<blockquote>
<p><strong>Do viruses, bacteria and other small things get crushed like an ant when stepped on? – Ryan L., age 12, Chapel Hill, North Carolina</strong></p>
</blockquote>
<hr>
<p>When you step on some things, like a banana, they squish and flatten to the ground. But when you step on other things, like a rock, they maintain their shape and aren’t affected. So what happens when you step on bacteria? Are they squishy?</p>
<p>While we work with microorganisms and other cells as chemical and biological engineers, neither of us has actually tried squishing them in the lab. One of us has a background in physics and <a href="https://scholar.google.co.in/citations?user=-LTVKKkAAAAJ&hl=en">studies mechanical forces in biology</a>, while one of us <a href="https://scholar.google.com/citations?user=9M8gP1YAAAAJ&hl=en">genetically engineers microorganisms</a> and cultivates them to make biofuels and other chemicals. </p>
<p>Between the two of us, we thought we could figure out the answer.</p>
<h2>Forces and pressures</h2>
<p>Let’s think about what happens when you step on something. Any time you push or pull on an object, you <a href="https://eng.libretexts.org/Bookshelves/Mechanical_Engineering/Mechanics_Map_(Moore_et_al.)/01%3A_Basics_of_Newtonian_Mechanics/1.02%3A_Forces">exert a force</a> on it. What happens after that depends on how much force you’re exerting and the properties of the object. </p>
<p>The force your footstep exerts comes mainly from your body weight. Also important is the <a href="https://eng.libretexts.org/Bookshelves/Mechanical_Engineering/Mechanics_Map_(Moore_et_al.)/04%3A_Statically_Equivalent_Systems/4.04%3A_Distributed_Forces#">area over which that force is distributed</a> on your foot, which creates pressure. That part about the area is important – it’s why you can walk on snow with snowshoes, but you’d sink with regular shoes.</p>
<p>You can calculate pressure by dividing the weight of an object by its area. If your foot is approximately a rectangle of 7 inches (about 18 centimeters) in length and 4 inches (10 cm) in width, it has a surface area of 28 square inches (180 square cm). And if your weight is 110 pounds (50 kilograms), the force you exert per square inch is roughly 3.9 pounds per square inch. </p>
<p>For comparison, the pressure of the air, or <a href="https://www.britannica.com/science/atmospheric-pressure">atmospheric pressure</a>, on your body at sea level is 14.7 pounds per square inch. The atmosphere exerts significantly more pressure on you than your footstep does on the ground – you just don’t feel it because it is balanced by the internal pressure of the air inside your body.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of Salmonella Typhimurium invading a human epithelial cell" src="https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=435&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=435&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=435&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=547&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=547&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=547&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It takes a little more than a stomp to kill bacteria like <em>Salmonella</em>.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2mbGDKv">NIAID/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Stepping on a microbe</h2>
<p>Now what happens to a bacterial cell when you apply the force of your footstep on it? </p>
<p>Bacteria <a href="https://microbiologysociety.org/why-microbiology-matters/what-is-microbiology/bacteria.html">have different shapes</a>, ranging from spheres to rods and spirals. Bacterial cells have walls that protect their gel-like insides from the environment. How strong is a bacterial cell wall, and can it withstand the force of your footstep?</p>
<p>Scientists have studied the strength of bacterial cell walls for several reasons, including to find out whether <a href="https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Boundless)/06%3A_Culturing_Microorganisms/6.14%3A_Physical_Antimicrobial_Control/6.14D%3A_High_Pressure">high pressure can kill bacteria</a>. People in the <a href="https://education.seattlepi.com/pressure-kill-bacteria-6032.html">food industry use high pressure</a> to make food such as milk safe for us to consume.</p>
<p>To determine the toughness of bacterial cell walls, researchers use a variety of tools to measure their <a href="https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Polymer_Chemistry_(Schaller)/04%3A_Polymer_Properties/4.07%3A_Stress-Strain_Relationships">ultimate tensile strength</a>, which is the maximum pressure an object can withstand before breaking. This can be done, for example, by putting them in a sealed container and rapidly lowering the pressure until they explode. A 1985 study found that it would take <a href="https://doi.org/10.1104/pp.79.2.485">nearly 1,500 pounds per square inch</a> to make the bacterium <em>Salmonella</em> explode, and later experiments showed it would take <a href="https://doi.org/10.1128/jb.173.1.197-203.1991">about 1,900 pounds per square inch</a> for the common soil bacterium <em>Bacillus subtilis</em> to explode. That’s 400 to 500 times more pressure than your sneaker is going to have on the sidewalk and any microbes lying about.</p>
<p>To understand these numbers in a different way, imagine a bacterium large enough for a person to stand on top of it. If it had the same cell wall strength as <em>Salmonella</em>, it could support over 350 people of 110 pounds each standing on it at the same time. While high pressures can kill bacteria in some applications such as <a href="https://doi.org/10.1007/s00253-011-3854-6">food processing</a>, one person standing on them won’t work.</p>
<h2>Slipping through the cracks</h2>
<p>It’s clear that bacterial cell walls are very strong. But there’s an added complication that makes it even harder to squish bacteria: They’re incredibly small. The average bacterium is only about <a href="http://book.bionumbers.org/how-big-is-an-e-coli-cell-and-what-is-its-mass/">1 to 5 microns or millionths of a meter</a> (smaller than ten-thousandth of an inch) in size. In comparison, the tip of a common pin is about 130 microns in diameter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of skin wrinkles" src="https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Your skin, like the soles of your shoes, contains grooves that bacteria can slide into to take off the pressure of getting stepped on.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/human-skin-royalty-free-image/177771717">deyangeorgiev/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>The surface of your skin has fine grooves called <a href="https://doi.org/10.1007/s10043-013-0014-5">sulci cutis</a> that are, on average, tens of microns deep. The soles of your shoes also have grooves that are much deeper than the ones in your skin. As a result, whether you are stepping on bacteria with your bare feet or while wearing shoes, most of the cells will slide into one of those grooves and escape from the full pressure you exert on the ground. </p>
<h2>Standing on a pin</h2>
<p>How could you increase the pressure your feet exert on a bacteria cell to squish it? </p>
<p>One theoretical way would be to change the bottoms of your shoes from flat to very pointy, with the bottom of the point having a diameter as wide as the tip of a pin. While walking on these shoes would be impossible, a 110-pound person would exert a pressure of 5.6 million pounds per square inch. That is enough to smash any known bacteria. </p>
<p>While people can’t actually do this, it turns out that some insects can. Cicada wings have <a href="https://doi.org/10.1002/smll.201200528">tiny molecular structures</a> that look like needles. These needle-like structures are only nanometers in size, a thousand times smaller than most bacteria, and are called nanorods. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/vTX2PHMLI9I?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Cicada wings are covered with cone-shaped nanopillars that can puncture bacteria.</span></figcaption>
</figure>
<p>When a bacterium lands on the surface of the cicada wing, it makes special chemicals that help it stick to the surface. When the bacteria divides, it produces tiny forces that allow the new cells to separate from each other. These small forces are magnified into enormous pressures when they push against the nanorods on the cicada wing, puncturing the bacteria and killing it.</p>
<p>Cicadas, dragonflies and many other flying insects have similar wing surfaces that are naturally bactericidal, meaning bacteria killing. Bioengineers are taking inspiration from nature and trying to make surfaces with needle-like structures that <a href="https://doi.org/10.1038/srep16817">kill bacteria in a similar way</a>.</p>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/199074/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>You can squash small bugs by stepping on them, but can you crush even tinier microorganisms like viruses and bacteria? It turns out that you’d need to apply a lot of pressure.Ashok Prasad, Associate Professor of Chemical and Biological Engineering, Colorado State UniversityKenneth F. Reardon, Professor of Chemical and Biological Engineering, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2048882023-05-04T19:06:29Z2023-05-04T19:06:29ZReconstructing ancient bacterial genomes can revive previously unknown molecules – offering a potential source for new antibiotics<figure><img src="https://images.theconversation.com/files/523906/original/file-20230502-2182-swsnio.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C8256%2C5499&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ancient DNA preserved in the tooth tartar of human fossils encodes microbial metabolites that could be the next antibiotic.</span> <span class="attribution"><a class="source" href="https://www.eurekalert.org/multimedia/983784?">Werner/Siemens Foundation</a></span></figcaption></figure><p>Microorganisms – in particular bacteria – are skillful chemists that can produce an impressive diversity of chemical compounds known as <a href="https://theconversation.com/nature-is-the-worlds-original-pharmacy-returning-to-medicines-roots-could-help-fill-drug-discovery-gaps-176963">natural products</a>. These metabolites provide the microbes major evolutionary advantages, such as allowing them to interact with one another or their environment and helping defend against different threats. Because of the diverse functions bacterial natural products have, many have been <a href="https://doi.org/10.1021/acs.jnatprod.5b01055">used as medical treatments</a> such as antibiotics and anti-cancer drugs.</p>
<p>The microbial species alive today represent only a tiny fraction of the vast diversity of microbes that have inhabited Earth over the past <a href="https://theconversation.com/were-viruses-around-on-earth-before-living-cells-emerged-a-microbiologist-explains-197880">3 billion years</a>. Exploring this microbial past presents exciting opportunities to recover some of their lost chemistry. </p>
<p>Directly studying these metabolites in archaeological samples is virtually impossible because of their <a href="https://doi.org/10.1007/s11306-017-1270-3">poor preservation</a> over time. However, reconstructing them using the genetic blueprints of long-dead microbes could provide a path forward. </p>
<p>We are a team of <a href="https://scholar.google.com/citations?user=cDFcc3cAAAAJ&hl=en">anthropologists</a>, <a href="https://scholar.google.de/citations?user=trnMQ7MAAAAJ&hl=en">archaeogeneticists</a> and <a href="https://scholar.google.com/citations?user=26MgwRgAAAAJ&hl=en">biochemists</a> who study ancient microbes. By <a href="https://www.science.org/doi/10.1126/science.adf5300">generating previously unknown chemical compounds</a> from the reconstructed genomes of ancient bacteria, our newly published research provides a proof of concept for the potential use of fossil microbes as a source of new drugs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Researcher weighing tooth fossil on a scale" src="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=565&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=565&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=565&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=710&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=710&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=710&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A single ancient tooth preserves the genomes of millions of ancient bacteria.</span>
<span class="attribution"><span class="source">Felix Wey/Werner Siemens Foundation</span></span>
</figcaption>
</figure>
<h2>Reconstructing ancient genomes</h2>
<p>The cellular machinery producing bacterial natural products is encoded in genes that are typically in close proximity to one another, forming what are called <a href="https://doi.org/10.1016/j.tim.2016.07.006">biosynthetic gene clusters</a>. Such genes are difficult to detect and reconstruct from ancient DNA because very old genetic material breaks down over time, fragmenting into thousands or even millions of pieces. The end result is numerous tiny DNA fragments <a href="https://doi.org/10.1038/s43586-020-00011-0">less than 50 nucleotides long</a> all mixed together like a jumbled jigsaw puzzle.</p>
<p>We sequenced billions of such ancient DNA fragments, then improved a bioinformatic process called <a href="https://doi.org/10.1007/s40484-019-0166-9">de novo assembly</a> to digitally order the ancient DNA fragments in stretches of up to 100,000 nucleotides long – a 2,000-fold improvement. This process allowed us to identify not only what genes were present, but also their order in the genome and the ways they differ from bacterial genes known today – key information to uncovering their evolutionary history and function. </p>
<p>This method allowed us to take an unprecedented look at the genomes of microbes living up to 100,000 years ago, including species not known to exist today. Our findings push back the <a href="https://doi.org/10.1038/s41586-021-03532-0">previously oldest</a> <a href="https://doi.org/10.1186/s40168-021-01132-8">reconstructed microbial genomes</a> by more than 90,000 years.</p>
<p>In the microbial genomes we reconstructed from DNA extracted from ancient tooth tartar, we found a gene cluster that was shared by a high proportion of Neanderthals and anatomically modern humans living during the <a href="https://www.britannica.com/event/Stone-Age/Middle-Paleolithic">Middle and Upper Paleolithic</a> that lasted from 300,000 to 12,000 years ago. This cluster bore the <a href="https://doi.org/10.1038/s43586-020-00011-0">molecular hallmarks of very ancient DNA</a> and belonged to the bacterial genus <em>Chlorobium</em>, a group of green sulfur bacteria capable of photosynthesis.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Chemical structure of paleofurans produced using ancient microbial DNA." src="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=280&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=280&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=280&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=351&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=351&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=351&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These paleofurans were produced from ancient microbial DNA.</span>
<span class="attribution"><span class="source">Pierre Stallforth</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>We inserted a synthetic version of this gene cluster into a “modern” bacterium called <em>Pseudomona protegens</em> so it could produce the chemical compounds encoded in the ancient genes. Using this method, we were able to isolate two previously unknown compounds we named <a href="https://www.science.org/doi/10.1126/science.adf5300">paleofuran A and B</a> and determine their chemical structure. Resynthesizing these molecules in the lab from scratch confirmed their structure and allowed us to produce larger quantities for further analysis.</p>
<p>By reconstructing these ancient compounds, our findings highlight how archaeological samples could serve as new sources of natural products. </p>
<h2>Mining ancient natural products</h2>
<p>Microbes are constantly evolving and adapting to their surrounding environment. Because the environments they inhabit today differ from those of their ancestors, microbes today likely produce different natural products than ancient microbes from tens of thousands of years ago.</p>
<p>As recently as <a href="https://www.doi.org/10.1007/978-1-4613-1145-4_1">25,000 to 10,000 years ago</a>, the Earth underwent a major climate shift as it transitioned from the colder and more volatile <a href="https://www.britannica.com/science/Pleistocene-Epoch">Pleistocene Epoch</a> to the warmer and more temperate <a href="https://www.britannica.com/science/Holocene-Epoch">Holocene Epoch</a>. Human lifestyles also dramatically changed over this transition as people began living outside of caves and increasingly experimented with food production. These changes brought them into contact with different microbes through agriculture, animal husbandry and their new built environments. Studying Pleistocene-era bacteria may yield insights into bacterial species and biosynthetic genes no longer associated with humans today, and perhaps even microbes that have gone extinct.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/JfX06NINZpk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Changes in human lifestyles changed our genomes.</span></figcaption>
</figure>
<p>While the amount of data collected by scientists on biological organisms has exponentially increased over the past few decades, the <a href="https://theconversation.com/antibiotic-resistance-is-at-a-crisis-point-government-support-for-academia-and-big-pharma-to-find-new-drugs-could-help-defeat-superbugs-169443">number of new antibiotics has stagnated</a>. This is particularly problematic when bacteria are able to evade existing antibiotic treatments faster than researchers can develop new ones. </p>
<p>By reconstructing microbial genomes from archaeological samples, scientists can tap into the hidden diversity of natural products that would have otherwise been lost over time, increasing the number of potential sources from which they can discover new drugs.</p>
<h2>Scaling up ancient molecules</h2>
<p>Our study has shown that it is possible to access natural products from the past. To tap into the vast diversity of chemical compounds encoded in ancient DNA, we now need to streamline our methodology to be less labor-intensive. </p>
<p>We are currently optimizing and automating our process to identify biosynthetic genes in ancient DNA more quickly and reliably. We are also implementing robotic liquid handling systems to complete the time-consuming pipetting and bacterial cultivation steps in our methods. Our goal is to scale up the process to be able to translate a vast amount of data on ancient microbes into the discovery of new therapeutic agents. </p>
<p>Although we can recreate ancient molecules, their biological and ecological roles are difficult to decipher. Since the bacteria that originally produced these compounds no longer exist, we cannot culture or genetically manipulate them. Further study will need to rely on similar bacteria that can be found today. Whether or not the functions of these compounds have remained the same in the modern relatives of ancient microbes remains to be tested. Although the original functions of these compounds for ancient microbes may be unknown, they still have the potential to be repurposed to treat modern diseases.</p>
<p>Ultimately, we aim to shed new light on microbial evolution and fight the current antibiotic crisis by providing a new time axis for antibiotic discovery.</p><img src="https://counter.theconversation.com/content/204888/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christina Warinner receives funding from the Werner Siemens Foundation, the Francis Goelet Charitable Trust, the European Research Council, the United States National Science Foundation, and the Deutsche Forschungsgemeinschaft. She is affiliated with the Max Planck Institute for Evolutionary Anthropology, the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI), and the Biological Faculty of Friedrich Schiller University Jena. </span></em></p><p class="fine-print"><em><span>Alexander Hübner receives funding from the Werner Siemens Foundation, the European Research Council, and the Deutsche Forschungsgemeinschaft. He is affiliated with with the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI).</span></em></p><p class="fine-print"><em><span>Pierre Stallforth receives funding from the Werner Siemens Foundation, the Deutsche Forschungsgemeinschaft, and the Leibniz Association. He is affiliated with with the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI) and the Friedrich Schiller University, Jena, Germany.</span></em></p>Ancient microbes likely produced natural products their descendants today do not. Tapping into this lost chemical diversity could offer a potential source of new drugs.Christina Warinner, Associate Professor of Anthropology, Harvard UniversityAlexander Hübner, Postdoctoral Researcher in Archaeogenetics, Max Planck Institute for Evolutionary AnthropologyPierre Stallforth, Professor of Bioorganic Chemistry and Paleobiotechnology, Friedrich-Schiller-Universität JenaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2034952023-05-03T12:10:09Z2023-05-03T12:10:09ZHow do ‘Candida auris’ and other fungi develop drug resistance? A microbiologist explains<figure><img src="https://images.theconversation.com/files/523473/original/file-20230428-18-9slhum.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2073%2C1368&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Candidiasis is a severe fungal infection that can spread easily in medical facilities.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/8ysD2e">Atlas of Pulmonary Pathology/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>One of the scariest things you can be told when at a doctor’s office is “You have an antimicrobial-resistant infection.” That means the bacteria or fungus making you sick can’t be easily killed with common antibiotics or antifungals, making treatment more challenging. You might have to take a combination of drugs for weeks to overcome the infection, which could result in more severe side effects.</p>
<p>Unfortunately, this diagnosis is <a href="https://www.who.int/publications/i/item/9789240062702">becoming more common around the world</a>.</p>
<p>The yeast <em><a href="https://doi.org/10.1128/jcm.01588-17">Candida auris</a></em> has recently emerged as a potentially dangerous fungal infection for hospital patients and nursing home residents. First <a href="https://doi.org/10.3947%2Fic.2022.0008">discovered in the late 2000s</a>, <em>Candida auris</em> has very quickly become a <a href="https://doi.org/10.3390/microorganisms9040807">major health challenge</a> due to its ease of spread and ability to resist common antifungal drugs.</p>
<p>How did this fungus become so strong, and what can researchers and physicians do to combat it? </p>
<p><a href="https://scholar.google.com/citations?user=U69z9VsAAAAJ&hl=en&oi=ao">I am a microbiologist</a> researching new ways to kill fungi. <em>Candida auris</em> and other fungi use three common cellular tricks to overcome treatments. Luckily, exciting new research hints at ways we can still fight this fungus.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/VOn5Udfx7eQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drug-resistant <em>Candida auris</em> infections are on the rise in the U.S. and around the world.</span></figcaption>
</figure>
<h2>Targeting the sensitive parts of fungal cells</h2>
<p>Fungal cells contain a structure called a <a href="https://doi.org/10.1128/microbiolspec.funk-0035-2016">cell wall</a> that helps maintain their shape and protects them from the environment. Fungal cell walls are constructed in part from several different types of polysaccharides, which are long strings of sugar molecules linked together. </p>
<p>Two polysaccharides found in almost all fungal cell walls are <a href="https://doi.org/10.1016/j.mib.2010.05.002">chitin</a> and <a href="https://doi.org/10.1016/j.tcsw.2019.100022">beta-glucan</a>. The fungal cell wall is an attractive target for drugs because human cells do not have a cell wall, so drugs that block chitin and beta-glucan production will have fewer side effects. </p>
<p>Some of the most common drugs used to treat fungal infections are called <a href="https://doi.org/10.4103%2F0253-7613.62396">echinocandins</a>. These drugs stop fungal cells from making beta-glucan, which significantly weakens their cell wall. This means the fungal cell can’t maintain its shape well. While the fungus is struggling to grow or is breaking apart, your immune system has a much better chance of fighting off the infection. </p>
<h2>How fungi become drug resistant</h2>
<p>Unfortunately, some strains of <em>Candida auris</em> are resistant to echinocandin treatment. But how does the fungus actually do it? For decades, scientists have been studying how fungi overcome drugs designed to weaken or kill them. In the case of echinocandins, <em>Candida auris</em> commonly uses three tricks to beat these treatments: <a href="https://doi.org/10.1128/AAC.00238-18">hide</a>, <a href="https://doi.org/10.1101%2Fcshperspect.a019752">build</a> and <a href="https://doi.org/10.3389/fmicb.2019.02573">change</a>. </p>
<p>The first trick is to hide in a complex mixture of sugars, proteins, DNA and cells <a href="https://doi.org/10.1128/msphere.00458-19">called a biofilm</a>. Made with irregular 3D structures, biofilms have lots of places for cells to hide. Drugs aren’t good at penetrating biofilms, so they can’t access and kill cells deep inside. Biofilms are especially problematic when they <a href="https://doi.org/10.3390/antibiotics4010001">grow on</a> <a href="https://doi.org/10.2147/ijn.s353071">medical equipment</a> like ventilators or catheters. Once free of a biofilm, cells that have gained the ability to resist the drugs a patient was taking become more dangerous.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of two types of Candida attaching to each other" src="https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This image shows <em>Candida albicans</em> (red) producing branching filaments that allow it to attach to <em>Candida glabrata</em> (green), forming biofilms. Both of these species can cause infections in people.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/HE7JbY">Edgerton Lab, State University of New York at Buffalo/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>The second trick fungi use to evade treatment is to build cell walls differently. Fungal cells treated with echinocandins can’t make beta-glucan. So instead, they start to <a href="https://doi.org/10.3109/13693786.2011.577104">make more chitin</a>, another important polysaccharide in the fungal cell wall. Echinocandins are unable to stop chitin production, so the fungus is still able to build a strong cell wall and avoid being killed. While there are some drugs that can <a href="https://doi.org/10.3390/jof6040261">stop chitin production</a>, none are currently approved for use in people. </p>
<p>The third trick fungi rely on is to <a href="https://doi.org/10.3389/fmicb.2019.02788">change the shape of the</a> <a href="https://doi.org/10.1093/cid/civ791">beta-glucan production enzyme</a> so echinocandins cannot block it. These mutations allow beta-glucan production to continue even in the presence of the drug. It is not surprising that <em>Candida</em> uses this trick to resist antifungal drugs since it is <a href="https://doi.org/10.1111%2Fnyas.12831">very effective</a> at keeping the cells alive. </p>
<h2>New tactics to fight fungi</h2>
<p>What can be done to treat echinocandin-resistant fungal infections? Thankfully, scientists and physicians are researching new ways to kill <em>Candida auris</em> and similar fungi. </p>
<p>The first approach is to find new drugs. For example, there are two drugs in development, <a href="https://doi.org/10.3390/antibiotics9050227">rezafungin</a> and <a href="https://doi.org/10.4155%2Ffmc-2018-0465">ibrexafungerp</a>, that appear to be able to stop beta-glucan production even in fungi resistant to echinocandins. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of budding yeast cells" src="https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This microscopy image shows budding yeast cells.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/budding-yeast-cell-in-gram-stain-royalty-free-image/1464904014">toeytoey2530/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>A complementary approach my research group is exploring is whether a class of enzymes called <a href="https://doi.org/10.1007/s11274-016-2068-6">glycoside hydrolases</a> might also be able to combat drug-resistant fungi. Some of these enzymes actively destroy the fungal cell wall, breaking apart both beta-glucan and chitin at the same time, which could potentially help prevent fungi from surviving on medical equipment or on hospital surfaces.</p>
<p>My lab’s work on discovering enzymes that strongly degrade fungal cell walls is part of a new strategy to combat antifungal resistance that uses a combination of approaches to kill fungi. But the end goal of this research is the same: having a physician tell you, “You’ve got a fungal infection, but we have a good treatment for it now.”</p><img src="https://counter.theconversation.com/content/203495/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeffrey Gardner receives funding from the National Science Foundation (NSF) and the National Institutes of Health (NIH).</span></em></p>Multidrug-resistant fungal infections are an emerging global health threat. Figuring out how fungi evade treatments offers new avenues to counter resistance.Jeffrey Gardner, Associate Professor of Biological Sciences, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2030582023-05-02T03:43:47Z2023-05-02T03:43:47ZHere’s why your freezer smells so bad – and what you can do about it<figure><img src="https://images.theconversation.com/files/523344/original/file-20230427-28-gy0qd6.jpg?ixlib=rb-1.1.0&rect=206%2C35%2C2568%2C1742&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">TY Lim/Shutterstock</span></span></figcaption></figure><p>Most people would expect a freezer can keep perishable food fresh and safe from spoilage for many months. Unfortunately, this is not always the case.</p>
<p>Have you ever noticed a funky smell in your freezer? Where does it come from and what can be done to fix the problem?</p>
<h2>Hardy microbes and pungent chemicals</h2>
<p>There are several causes for bad smells coming from your freezer. Typically, the culprits are microbes – bacteria, yeasts and moulds.</p>
<p>Although a freezer dramatically slows down the growth of most common spoilage microbes, some can still thrive if the temperature rises above -18°C (<a href="https://www.foodsafety.asn.au/topic/fridge-freezer-foodsafety/">the recommended freezer temperature</a>). This can happen if there is a power outage for more than a few hours, or if you put something hot straight in the freezer.</p>
<p>Food spills and open containers provide an opportunity for microbes to get to work. It’s also worth noting that many microbes will <a href="https://www.safefood.qld.gov.au/newsroom/food-safety-myths-continued/?keyword=freezing">survive freezing</a> and start growing again once conditions are favourable – for example, if you remove the food, partially thaw it, and return it to the freezer.</p>
<p>Two things happen when food breaks down. First, as microbes start to grow, several pungent chemicals are produced. Second, the fats and flavours that are part of the food itself can and will be released.</p>
<p>These are generally referred to as volatile organic compounds (VOCs). They are the pleasant aromas that we sense when we eat, but VOCs can also be produced by bacteria.</p>
<p>For example, many of us would be familiar with the smells that come from fermentation – a microbial process. When fermenting a food, we intentionally contaminate it with microbes of known characteristics, or provide conditions that favour the growth of desirable microbes and subsequent production of aromatic compounds.</p>
<p>By contrast, uncontrolled food spoilage is problematic, especially when the contaminating microbes can cause disease.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523356/original/file-20230428-28-iqy59g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of chopsticks picking up a piece of kimchi from a white bowl" src="https://images.theconversation.com/files/523356/original/file-20230428-28-iqy59g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523356/original/file-20230428-28-iqy59g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523356/original/file-20230428-28-iqy59g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523356/original/file-20230428-28-iqy59g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523356/original/file-20230428-28-iqy59g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523356/original/file-20230428-28-iqy59g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523356/original/file-20230428-28-iqy59g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Kimchi is one of the foods we deliberately allow to be ‘contaminated’ in order to produce the intense flavour.</span>
<span class="attribution"><span class="source">Nungning20/Shutterstock</span></span>
</figcaption>
</figure>
<h2>Freezing changes the food</h2>
<p>It is not only microbial growth that can lead to undesirable odours. There’s a suite of chemical processes happening in the freezer, too.</p>
<p>Freezing causes physical changes to foods, often enhancing their breakdown. Many of us would be familiar with “freezer burn” on meats and other foods, as well as ice crystals on frozen food.</p>
<p>This phenomenon is called “<a href="https://en.wikipedia.org/wiki/Brine_rejection">salt rejection</a>”. Depending on how rapidly something is frozen, salts can sometimes be concentrated, as pure water freezes at a higher temperature than water with things dissolved in it – like sugars and salts. On a large scale, this happens to icebergs in the ocean. As the sea water freezes, salt is removed. Thus, the iceberg is composed of fresh water, and the surrounding sea water becomes a saltier and denser brine.</p>
<p>In a similar way, as water in food freezes, organic molecules are concentrated and expelled. If these are volatile, they move about the freezer and stick to other things. Where they end up depends on what else is around.</p>
<p>Some of the volatiles like water. We call them “hydrophilic” or water loving; those are the ones that will make your food taste bad. Other are more water-hating or “hydrophobic” and they stick to things like silicone ice cube trays, <a href="https://www.nytimes.com/wirecutter/blog/how-to-get-smells-out-of-silicone-kitchenware/">making them go smelly</a>.</p>
<p>Domestic freezers are commonly attached to a refrigerator, and this provides another opportunity for smells to move through the systems. The two units share a single cooling source and airflow channel. If your fridge has foul odours from the food inside (natural or after microbial spoilage), it is very likely they will migrate to your freezer.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-colour-coding-your-fridge-can-stop-your-greens-going-to-waste-45703">How colour-coding your fridge can stop your greens going to waste</a>
</strong>
</em>
</p>
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<h2>Help, my freezer smells!</h2>
<p>There are some simple steps you can take to stop your freezer from smelling.</p>
<p>First, try to prevent odours from developing in the first place by covering the food. If you place food in an airtight container (glass is best), it will dramatically slow the release of any aromatic compounds produced by bacteria or the food itself. Covered food is also less likely to absorb smells and flavours from other foods around it.</p>
<p>If the smells have already developed, you can eliminate them by following a few simple steps, including a thorough clean.</p>
<ul>
<li><p>Remove all items from the freezer and inspect the foods for any spoilage, freezer burn or unpleasant odours. </p></li>
<li><p>Discard anything that has developed ice crystals and store the rest in a cooler box while attending to the freezer itself. You should also inspect the fridge and discard any bad-smelling foods. </p></li>
<li><p>Once you have removed all items, take out the shelves and clean up spills or crumbs. </p></li>
<li><p>Wipe down all surfaces using warm soapy water or a mix of two tablespoons of baking soda with warm water.</p></li>
<li><p>Wash all the shelves and ice compartments and let them dry completely. </p></li>
</ul>
<p>If the smells are not removed with these simple cleaning steps, the freezer may require a deep clean, which involves turning off the unit and letting it “breathe” for a few days.</p>
<p>Placing some baking soda inside the freezer before adding food can help to absorb any residual odours. For serious smells where crevices or insulation are contaminated, you may need a service technician.</p>
<p>In short, even though we think freezers keep things “fresh”, microbes can still proliferate in there. Make sure to clean your freezer now and then to keep your food safe and healthy.</p><img src="https://counter.theconversation.com/content/203058/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Do your ice taste funny? Is there ‘freezer burn’ on your meat? This is why your freezer probably isn’t as clean as you think – but it only takes a few simple steps to fix it.Enzo Palombo, Professor of Microbiology, Swinburne University of TechnologyRosalie Hocking, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2002262023-04-11T12:04:46Z2023-04-11T12:04:46ZLooming behind antibiotic resistance is another bacterial threat – antibiotic tolerance<figure><img src="https://images.theconversation.com/files/519955/original/file-20230407-28-ddggzn.jpg?ixlib=rb-1.1.0&rect=0%2C3%2C2309%2C1292&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tolerant bacteria are dormant until an antibiotic threat has passed, then reemerge to conduct business as usual.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/pseudomonas-aeruginosa-bacterium-illustration-royalty-free-image/1201441647">Christoph Burgstedt/Science Photo Library via Getty Images</a></span></figcaption></figure><p>Have you ever had a nasty infection that just won’t seem to go away? Or a runny nose that keeps coming back? You may have been dealing with a bacterium that is tolerant of, though not yet resistant to, antibiotics. </p>
<p>Antibiotic resistance is a huge problem, contributing to <a href="https://doi.org/10.1016/S0140-6736(21)02724-0">nearly 1.27 million deaths worldwide in 2019</a>. But antibiotic tolerance is a covert threat that researchers have only recently begun to explore. </p>
<p><a href="https://doi.org/10.1371/journal.ppat.1008892">Antibiotic tolerance</a> happens when a bacterium manages to survive for a long time after being exposed to an antibiotic. While <a href="https://doi.org/10.1128/microbiolspec.VMBF-0016-2015">antibiotic-resistant</a> bacteria flourish even in the presence of an antibiotic, tolerant bacteria often exist in a dormant state, neither growing nor dying but putting up with the antibiotic until they can “reawaken” once the stress is gone. Tolerance has been <a href="https://www.doi.org/10.1126/science.aaj2191">linked to the spread of antibiotic resistance</a>.</p>
<p>I am a <a href="https://doerr.wicmb.cornell.edu/current-lab-members/">microbiologist</a> who studies antibiotic tolerance, and I seek to uncover what triggers tolerant bacteria to enter a protective dormant slumber. By understanding why bacteria have the ability to become tolerant, researchers hope to develop ways to avoid the spread of this ability. The exact mechanism that sets tolerance apart from resistance has been unclear. But one possible answer may reside in a process that has been overlooked for decades: how bacteria <a href="https://doi.org/10.3389/fmicb.2020.577564">create their energy</a>.</p>
<h2>Cholera and antibiotic tolerance</h2>
<p>Many antibiotics are designed to <a href="https://doi.org/10.1039/C6MD00585C">break through the bacteria’s outer defenses</a> like a cannonball through a stone fortress. Resistant bacteria are immune to the cannonball because they can either destroy it before it damages their outer wall or change their own walls to be able to withstand the impact. </p>
<p>Tolerant bacteria can remove their wall entirely and avoid damage altogether. No wall, no target for the cannonball to smash. If the threat goes away before too long, the bacterium can rebuild its wall to protect it from other environmental dangers and resume normal functions. However, it is still unknown how bacteria know the antibiotic threat is gone, and what exactly triggers their reawakening. </p>
<p>My colleagues and I at the <a href="https://doerr.wicmb.cornell.edu/">Dörr Lab at Cornell University</a> are trying to understand processes of activation and reawakening in the tolerant bacteria responsible for cholera, <em>Vibrio cholerae</em>. <em>Vibrio</em> is <a href="https://doi.org/10.3389/fitd.2021.691604">rapidly evolving resistance</a> against various types of antibiotics, and doctors are concerned. As of 2010, <em>Vibrio</em> is already <a href="https://doi.org/10.1016/j.vaccine.2019.06.031">resistant to 36 different antibiotics</a>, and this number is expected to continue rising.</p>
<p>To study how <em>Vibrio</em> develops resistance, we chose a strain that is tolerant to a class of antibiotics <a href="https://doi.org/10.3389/fpubh.2016.00231">called beta-lactams</a>. Beta-lactams are the cannonball sent to destroy the bacteria’s fortress, and <em>Vibrio</em> adapts by activating two genes that temporarily remove its cell wall. I witnessed this phenomenon using a microscope. After removing its cell wall, the bacteria activate even more genes that morph it into fragile globs that can survive the effects of the antibiotic. Once the antibiotic is removed or degraded, <em>Vibrio</em> returns to its normal rod shape and continues to grow. </p>
<figure>
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<figcaption><span class="caption">Normally rod-shaped <em>Vibrio cholerae</em> remove their cell walls and turn into globs in the presence of penicillin, enabling them to survive longer.</span></figcaption>
</figure>
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<figcaption><span class="caption"><em>Vibrio cholerae</em> revert back to their rod-shaped structure once the antibiotic threat is removed.</span></figcaption>
</figure>
<p>In people, this process of tolerance is seen when a doctor prescribes an antibiotic, typically doxycycline, to a patient infected with cholera. The antibiotic temporarily seems to stop the infection. But then the symptoms start back up again because the antibiotics never fully cleared the bacteria in the first place.</p>
<p>The ability to revert back to normal and grow after the antibiotic is gone is the key to tolerant survival. Exposing <em>Vibrio</em> to an antibiotic for a long enough time would eventually kill it. But a standard course of antibiotics often isn’t long enough to get rid of all the bacteria even in their fragile state.</p>
<p>However, taking a medicine for a prolonged period can harm healthy bacteria and cells, causing further discomfort and illness. Additionally, <a href="https://doi.org/10.3389/fcimb.2020.572912">misuse and extended exposure</a> to antibiotics can increase the chances of other bacteria residing in the body becoming resistant.</p>
<h2>Other bacteria developing tolerance</h2>
<p><em>Vibrio</em> isn’t the only species to exhibit tolerance. In fact, researchers have recently identified many infectious bacteria that have developed tolerance. A bacteria family called <a href="https://doi.org/10.1371/journal.pbio.1001928">Enterobacteriaceae</a>, which include major food-borne disease pathogens <a href="https://doi.org/10.1371/journal.pbio.1001928"><em>Salmonella</em></a>, <a href="https://doi.org/10.1128/AAC.01282-08"><em>Shigella</em></a> and <a href="https://doi.org/10.1038/s41598-021-85509-7"><em>E. coli</em></a>, are just a few of the many types of bacteria that are capable of antibiotic tolerance.</p>
<p>As every bacterium is unique, the way one develops tolerance seems to be as well. Some bacteria, like <em>Vibrio</em>, <a href="https://doi.org/10.1128/AAC.00756-19">erase their cell walls</a>. Others can <a href="https://doi.org/10.1038/nchembio.1754">alter their energy sources, increase their ability to move or simply pump out</a> the antibiotic.</p>
<p>I recently found that a <a href="https://doi.org/10.1128/jb.00476-22">bacterium’s metabolism</a>, or the way it breaks down “food” to make energy, may play a significant role in its ability to become tolerant. Different structures within a bacterium, including its outer wall, are made of specific building blocks like proteins. Stopping the bacterium’s ability to craft these pieces weakens its wall, making it more likely to take damage from the outside environment before it can take the wall down.</p>
<h2>Tolerance and resistance are connected</h2>
<p>Although there has been considerable research on how bacteria develop tolerance, a key piece of the puzzle that has been neglected is how tolerance leads to resistance.</p>
<p>In 2016, researchers discovered how to <a href="https://doi.org/10.1038/nmicrobiol.2016.20">make bacteria tolerant in the laboratory</a>. After repeated exposure to different antibiotics, <em>E. coli</em> cells were able to adapt and survive. DNA, the genetic material containing instructions for cell function, is a fragile molecule. When DNA is damaged rapidly by stress, such as antibiotic exposure, the cell’s repair mechanisms tend to mess up and cause mutations that can create resistance and tolerance. Because <em>E. coli</em> is similar to many different types of bacteria, these researchers’ findings revealed that, ironically, essentially any bacteria can develop tolerance if pushed to their limits by the antibiotics meant to kill them. </p>
<figure>
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<figcaption><span class="caption">Bacteria form large communities in biofilms.</span></figcaption>
</figure>
<p>Another recent key discovery was that the longer bacteria remain tolerant, the more likely they are to <a href="https://doi.org/10.1073/pnas.2209043119">develop mutations leading to resistance</a>. Tolerance allows bacteria to develop a resistance mutation that reduces their chances of being killed during antibiotic treatment. This is especially relevant to bacterial communities often seen in <a href="https://doi.org/10.2147/IDR.S379502">biofilms that tend to coat high-touch surfaces in hospitals</a>. Biofilms are slimy layers of bacteria that ooze a protective jelly that makes antibiotic treatment difficult and DNA sharing between microbes easy. They can induce bacteria to evolve resistance. These conditions are thought to mimic what could be happening during antibiotic-treated infections, in which many bacteria are living next to one another and sharing DNA. </p>
<p>Researchers are calling for more research into antibiotic tolerance with the hope that it will lead to <a href="https://doi.org/10.1128/mBio.02095-19">more robust treatments</a> in both infectious diseases and cancers. And there is reason to be hopeful. In one promising development, a mouse study found that <a href="https://doi.org/10.1126/science.1211037">decreasing tolerance also reduced resistance</a>. </p>
<p>Meanwhile, there are steps everyone can take to aid in the battle against antibiotic tolerance and resistance. You can do this by <a href="https://www.who.int/news-room/fact-sheets/detail/antibiotic-resistance">taking an antibiotic exactly as prescribed</a> by a doctor and finishing the entire bottle. Brief, inconsistent exposure to a medicine primes bacteria to become tolerant and eventually resistant. Smarter use of antibiotics by everyone can stop the evolution of tolerant bacteria.</p><img src="https://counter.theconversation.com/content/200226/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Megan Keller receives funding from the National Science Foundation Graduate Research Fellowship Program and the National Institutes of Health (NSF GRFP #DGE-1650441 and NIH R01-AI143704)</span></em></p>Antibiotic resistance has contributed to millions of deaths worldwide. Research suggests that any bacteria can develop antibiotic tolerance, and possibly resistance, when pushed to their limits.Megan Keller, Ph.D. Candidate in Microbiology, Cornell UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1968742023-02-14T13:27:07Z2023-02-14T13:27:07ZHow do blood tests work? Medical laboratory scientists explain the pathway from blood draw to diagnosis and treatment<figure><img src="https://images.theconversation.com/files/509538/original/file-20230210-16-9ds3x9.jpg?ixlib=rb-1.1.0&rect=15%2C0%2C2101%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pathology analyzes bodily fluids and tissues using a variety of methods.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/doctor-manipulating-blood-plasma-tubes-green-royalty-free-image/1404395240">Alvaro Lavin/Moment via Getty Images</a></span></figcaption></figure><p>Medical laboratory testing is the heartbeat of medicine. It provides critical data for physicians to diagnose and treat disease, <a href="https://doi.org/10.1093/labmed/lmaa098">dating back thousands of years</a>. Unfortunately, laboratory medicine as a field is poorly understood by both the public and health care communities. </p>
<p><a href="https://asm.org/Articles/2021/October/Using-Laboratory-Medicine-to-Support-Direct-Patien">Laboratory medicine</a>, also known as clinical pathology, is one of two main branches of pathology, or the study of the causes and effects of disease. Pathology covers many <a href="https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=85&contentid=P00955">laboratory areas</a>, such as blood banking and microbiology. Clinical pathology diagnoses a disease through laboratory analysis of body fluids such as blood, urine, feces and saliva. The other branch of pathology, <a href="https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/anatomical-pathology">anatomic pathology</a>, diagnoses a disease by examining body tissues.</p>
<p>We are <a href="https://scholar.google.com/citations?user=8XtvOZ8AAAAJ&hl=en">public health</a> and <a href="https://www.rushu.rush.edu/faculty/nicholas-moore-ms-mlsascpcm">medical laboratory</a> scientists who specialize in microbiology and infectious diseases. There are a lot of steps between when your doctor orders a blood test to establishing a diagnosis. From the bedside to the lab bench, here’s how laboratory testing works.</p>
<h2>It all starts with a specimen</h2>
<p>When you see a doctor, sometimes a physical exam and detailed medical history are enough for them to make a diagnosis, offer recommendations or prescribe medications for your condition. There are many instances, however, where your doctor may need additional information to make an accurate diagnosis. This information is often obtained from procedures like <a href="https://medlineplus.gov/ency/article/007451.htm">imaging scans</a> or <a href="https://doi.org/10.1309/LM4O4L0HHUTWWUDD">blood tests</a>.</p>
<p>The first step involves getting your blood drawn through a practice known as <a href="https://www.webmd.com/a-to-z-guides/what-is-phlebotomy">phlebotomy</a>. A health care professional, typically a phlebotomist or a nurse, inserts a needle into a vein to collect a blood specimen. </p>
<p>Multiple tubes of blood may be needed, as certain tests are only performed using certain types of blood specimens. For example, one test commonly used to <a href="https://www.nhlbi.nih.gov/health/anemia">diagnose anemia</a> requires blood to be collected in a chemical that prevents the blood from clotting. Patients being evaluated for a <a href="https://www.nhlbi.nih.gov/health/clotting-disorders">clotting disorder</a>, on the other hand, often have their blood collected in a tube containing another anticoagulant.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/509533/original/file-20230210-15-axvazu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Array of blood test tubes in a rack" src="https://images.theconversation.com/files/509533/original/file-20230210-15-axvazu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/509533/original/file-20230210-15-axvazu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/509533/original/file-20230210-15-axvazu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/509533/original/file-20230210-15-axvazu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/509533/original/file-20230210-15-axvazu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/509533/original/file-20230210-15-axvazu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/509533/original/file-20230210-15-axvazu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Different tests require different types of blood specimens.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/rack-with-tubes-blood-samples-from-patients-for-royalty-free-image/1446655782">angelp/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<h2>Testing pathways</h2>
<p>Specimens then make their way to a clinical laboratory. Laboratories can be found within hospitals, reference labs or physician offices, or they can be located in a public health setting such as the Centers for Disease Control and Prevention or a state public health laboratory. In 2021, there were <a href="https://www.bls.gov/ooh/healthcare/clinical-laboratory-technologists-and-technicians.htm#tab-1">more than 329,000 laboratory professionals</a> working in the U.S. in <a href="https://www.cms.gov/regulations-and-guidance/legislation/clia#">more than 320,000 federally regulated laboratories</a>. An estimated <a href="https://www.cdc.gov/csels/dls/strengthening-clinical-labs.html">14 billion laboratory tests</a> are ordered annually in the U.S., on top of <a href="https://www.worldometers.info/coronavirus/#countries">over 1 billon COVID-19 tests</a> during the pandemic. With such a large volume of specimens to test and examine, various sections of a laboratory are automated. </p>
<p>Laboratory tests examine the biological, chemical and physical properties of the cells and molecules that make up a blood specimen. The first step is often to centrifuge a blood specimen into separate components. This divides the sample into one portion that contains solid components, such as cells, and another that contains liquid components and dissolved solutes, known as serum or plasma.</p>
<p>Analyzing the serum or plasma portion of a blood specimen measures the levels of different substances within the body. One of the most common is your blood sugar, or glucose concentration. For the doctors of <a href="https://www.cdc.gov/csels/dls/strengthening-clinical-labs.html">more than 37 million Americans with diabetes</a>, knowing how high their patient’s blood glucose is helps them establish a new diagnosis or ensure their condition is under control.</p>
<p>If your doctor suspects you have an infection, they will collect specimens to test for the presence of a pathogen. For example, they might collect a throat swab for strep throat or a urine sample for a urinary tract infection. Scientists incubate these samples to screen any organisms that grow and resemble pathogens of interest. They may perform additional testing to identify the microbe. Once an organism is identified, the <a href="https://deepdive.tips/index.php/2022/12/01/putting-a-face-on-clinical-laboratory-sciences-w-dr-rodney-rohde/">medical laboratory professional</a> can then test a variety of antimicrobial agents against it to inform your doctor what the best treatment would be against your infection.</p>
<h2>Evolution of medical laboratory testing</h2>
<p>The <a href="https://doi.org/10.1093/clinchem/43.1.174">first hospital clinical laboratory in the U.S.</a> was established in 1894. Some of the methods <a href="https://deepdive.tips/index.php/2022/12/01/putting-a-face-on-clinical-laboratory-sciences-w-dr-rodney-rohde/">laboratory professionals</a> use to analyze samples have been in use for over a century. </p>
<p>One such staple, the <a href="https://www.ncbi.nlm.nih.gov/books/NBK562156/">Gram stain</a>, was introduced in 1882. It uses two different dyes and exploits differences in the bacterial cell wall to discriminate between two different groups of bacteria. This helps lab scientists identify the correct antimicrobial therapy to use against an infection.</p>
<p>Another commonly used technology, the <a href="https://doi.org/10.1002/cyto.a.24505">Coulter Principle</a>, was developed in the 1940s to identify and sort individual cells based on physical size and resistance to an electrical current. Medical laboratory professionals routinely use this technique to conduct <a href="https://medlineplus.gov/lab-tests/complete-blood-count-cbc/">complete blood count</a> tests, which measure unusual increases or decreases in the number of different types of blood cells that could provide insights into a disease or condition, such as cancer or sickle cell anemia.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510360/original/file-20230215-28-e6jp0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Medical laboratory professional holding blood tube" src="https://images.theconversation.com/files/510360/original/file-20230215-28-e6jp0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510360/original/file-20230215-28-e6jp0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510360/original/file-20230215-28-e6jp0p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510360/original/file-20230215-28-e6jp0p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510360/original/file-20230215-28-e6jp0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510360/original/file-20230215-28-e6jp0p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510360/original/file-20230215-28-e6jp0p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Medical laboratory professionals use different techniques to analyze samples.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/feamle-scientist-preparing-a-blood-sample-for-royalty-free-image/1023297260">Westend61/Getty Images</a></span>
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</figure>
<p>In 1986, scientists devised the <a href="https://www.nobelprize.org/prizes/chemistry/1993/mullis/facts/">Nobel Prize-winning</a> <a href="https://www.ncbi.nlm.nih.gov/probe/docs/techpcr/">polymerase chain reaction</a> method to amplify, or rapidly produce, multiple copies of the DNA of a pathogen present within a sample. PCR is widely used to diagnose infections, identify genetic disorders and monitor cancer progression.</p>
<p>An explosion of modern laboratory tools to research and diagnose disease followed PCR. To name a few of these cutting-edge tools, <a href="https://doi.org/10.1038/labinvest.2014.156">matrix-assisted laser desorption ionization, or MALDI</a>, is one of the most commonly used techniques to identify microbes that are difficult or impossible to culture. Genome editing and <a href="https://medlineplus.gov/genetics/understanding/genomicresearch/genomeediting/">CRISPR-Cas9</a> give scientists the ability to change an organism’s DNA, aiding in <a href="https://doi.org/10.1016/j.biopha.2021.111487">identifying pathogens and detecting dysfunctional genes</a> by adding, removing or altering genes of interest. <a href="https://theconversation.com/genomic-sequencing-heres-how-researchers-identify-omicron-and-other-covid-19-variants-172935">Next-generation sequencing</a> has become a powerful modern tool to determine the sequence of the genetic material in biological samples and has been extensively used to <a href="https://doi.org/10.3390%2Fijms12117861">identify variants</a> and wastewater surveillance of pathogens like the virus that causes COVID-19.</p>
<h2>Challenges and solutions</h2>
<p>One of the most critical challenges in laboratory medicine is <a href="https://doi.org/10.1309/LM4O4L0HHUTWWUDD">understanding and interpreting test results</a>, because errors can occur throughout the testing process. Specimens must be properly collected and transported to the lab for accurate results. Likewise, at-home tests need to be properly stored. Clinicians and patients need to take into account the chances of false positive or negative results by considering the <a href="https://theconversation.com/coronavirus-tests-are-pretty-accurate-but-far-from-perfect-136671">limitations of the test</a> alongside the patient’s individual case.</p>
<p>Collaboration between clinicians and medical laboratory professionals could help <a href="https://www.elsevier.com/connect/preventing-diagnostic-errors-by-uniting-the-clinical-laboratory-with-direct-patient-care">reduce errors</a> in diagnosis and treatment. Laboratory data can and often is extremely useful to patient care, but a holistic approach that takes into account a patient’s medical history, genetics and health habits, among other factors, is necessary for an accurate diagnosis and treatment. While powerful, a laboratory result should not be used in isolation. Clear and accurate communication on laboratory testing is critical for effective patient care.</p>
<p><em>A photo was replaced to more accurately reflect medical laboratory work</em></p><img src="https://counter.theconversation.com/content/196874/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rodney E. Rohde has received funding from the American Society of Clinical Pathologists, American Society for Clinical Laboratory Science, U.S. Department of Labor (OSHA), and other public and private entities/foundations. Rohde is affiliated with ASCP, ASCLS, ASM, and serves on several scientific advisory boards. See <a href="https://rodneyerohde.wp.txstate.edu/service/">https://rodneyerohde.wp.txstate.edu/service/</a>.</span></em></p><p class="fine-print"><em><span>Nicholas Moore previously received funding from Abbott Molecular, bioMerieux, and Cepheid for contracted research work related to the development of laboratory assays. Funds were paid directly to Rush University. Nicholas Moore is a volunteer with the American Society for Clinical Laboratory Science, the American Society for Clinical Pathology, the American Society for Microbiology, and the Clinical and Laboratory Standards Institute. He is a member of the editorial board of Clinical Microbiology Reviews and BMC Infectious Diseases.</span></em></p>Lab testing provides doctors with essential information to help them diagnose and treat disease. Here’s what happens behind the scenes after you roll up your sleeve for a blood draw.Rodney E. Rohde, Regents' Professor of Clinical Laboratory Science, Texas State UniversityNicholas Moore, Associate Professor of Medical Laboratory Science, Rush UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1927232023-01-05T20:37:28Z2023-01-05T20:37:28ZNo, you shouldn’t wash raw chicken before cooking it. So why do people still do it?<figure><img src="https://images.theconversation.com/files/490251/original/file-20221018-17274-k1s6c8.jpg?ixlib=rb-1.1.0&rect=0%2C18%2C6256%2C4108&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Food safety authorities and regulators <a href="https://foodsafety.asn.au/topic/tips-poultry/">around</a> <a href="https://www.cdc.gov/foodsafety/chicken.html#:%7E:text=after%20handling%20chicken.-,Do%20not%20wash%20raw%20chicken.,that%20previously%20held%20raw%20chicken.">the</a> <a href="https://www.food.gov.uk/safety-hygiene/cleaning">world</a> <a href="https://www.mpi.govt.nz/food-safety-home/preparing-and-storing-food-safely-at-home/clean-cook-chill/#:%7E:text=Don't%20wash%20raw%20chicken,food%20poisoning%20from%20campylobacter%20bacteria.">recommend</a> you don’t wash raw poultry before cooking. </p>
<p>That’s because washing chicken can splash dangerous bacteria around the kitchen. It’s best just to thoroughly cook the chicken without washing it, so it is safe to eat.</p>
<p>Despite this, chicken-washing remains common. A <a href="https://www.safefood.qld.gov.au/newsroom/does-raw-chicken-need-rinsing/">survey</a> by Australia’s Food Safety Information Council showed almost half of Australian home cooks washed whole chickens before cooking. Dutch research found <a href="https://www.foodsafetynews.com/2022/05/dutch-survey-finds-a-quarter-of-people-wash-chicken-despite-expert-advice/">25%</a> of consumers washed their chicken often or almost always.</p>
<p>So why do people do it – and what does the research say about the risks of chicken-washing?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/490247/original/file-20221017-18129-wt6pzf.jpg?ixlib=rb-1.1.0&rect=0%2C48%2C5391%2C3535&q=45&auto=format&w=1000&fit=clip"><img alt="A person washes chicken over a sink." src="https://images.theconversation.com/files/490247/original/file-20221017-18129-wt6pzf.jpg?ixlib=rb-1.1.0&rect=0%2C48%2C5391%2C3535&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490247/original/file-20221017-18129-wt6pzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490247/original/file-20221017-18129-wt6pzf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490247/original/file-20221017-18129-wt6pzf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490247/original/file-20221017-18129-wt6pzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490247/original/file-20221017-18129-wt6pzf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490247/original/file-20221017-18129-wt6pzf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Australia’s Food Safety Information Council recommends raw poultry not be washed before cooking.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/yes-you-can-reheat-food-more-than-once-heres-why-184158">Yes, you can reheat food more than once. Here's why</a>
</strong>
</em>
</p>
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<h2>Chicken meat and germs</h2>
<p>Incorrect cooking temperatures and cross-contamination between different foods are two of the most important factors linked to foodborne illness. </p>
<p>This is particularly relevant to poultry meat. Two leading causes of foodborne illness are the bacteria <em><a href="https://www.cdc.gov/campylobacter/index.html">Campylobacter</a></em> and <em><a href="https://www.cdc.gov/foodsafety/communication/salmonella-food.html">Salmonella</a></em>, which are commonly found on raw poultry. </p>
<p>In Australia, reported cases of <em>Campylobacter</em> and <em>Salmonella</em> have almost <a href="https://foodsafety.asn.au/topic/tips-poultry/">doubled</a> over the last two decades. </p>
<p>Of the estimated 220,000 cases of <em>Campylobacter</em> infection each year, <a href="https://foodsafety.asn.au/topic/tips-poultry/">50,000</a> can be attributed either directly or indirectly to chicken meat. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/491574/original/file-20221025-19-osvds4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Chicken is grilled on a barbecue." src="https://images.theconversation.com/files/491574/original/file-20221025-19-osvds4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491574/original/file-20221025-19-osvds4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491574/original/file-20221025-19-osvds4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491574/original/file-20221025-19-osvds4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491574/original/file-20221025-19-osvds4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491574/original/file-20221025-19-osvds4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491574/original/file-20221025-19-osvds4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Why do many home cooks continue to wash chicken before cooking?</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/barbecue-bbq-beef-chicken-262945/">Photo by Pixabay</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>Chicken-washing myths, busted</h2>
<p>One <a href="https://doi.org/10.1016/j.foodcont.2020.107682">analysis</a> of consumer responses to an education campaign about the dangers of washing raw poultry shed light on why many people still wash raw chicken before cooking.</p>
<p>Some believe there is a need to wash faeces and other matter off the chicken meat. In fact, modern processing techniques mean chicken carcasses do not need additional cleaning. </p>
<p>Others believe washing with a slightly acidic solution (such as vinegar or lemon juice) will kill bacteria. </p>
<p>On the contrary, <a href="https://doi.org/10.1016/j.foodcont.2018.06.034">research</a> has shown washing raw poultry in lemon juice or vinegar does not remove bacteria and can increase the cross-contamination risk.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1519397720200339456"}"></div></p>
<h2>Washing chicken splashes bacteria around</h2>
<p>One of the more compelling arguments why washing raw poultry under a running tap is a risky activity comes from <a href="https://doi.org/10.1063/5.0083979">recent research</a> on water droplets ejected from the surface of washed chicken. </p>
<p>The study clearly showed bacteria can be transferred from the surface of the chicken to surrounding surfaces via water droplets.</p>
<p>Using high-speed imaging, the researchers found a higher tap height can increase splashing. </p>
<p>Chicken meat is often soft and the water flow can create a divot in the surface. This leads to splashing that would not occur on a curved, hard surface. </p>
<p>The researchers placed large agar plates next to the chicken surfaces to capture any water droplets. This allowed them to grow the bacteria that were transferred with the splashed water. </p>
<p>They found the level of bacterial transmission increased with greater tap height and water flow rate. </p>
<p>Aerated water (which is what you get when the tap is running very hard) also increased splashing and bacterial transmission. </p>
<h2>What if I still really want to wash my chicken meat?</h2>
<p>While washing raw poultry is not recommended, it appears some home cooks are reluctant to let go of this old habit. </p>
<p>If you insist on washing chicken meat, consider doing so in a sink of water rather than under a running tap.</p>
<p>Use a paper towel to mop up any liquids, dispose of the towel and clean up afterwards. </p>
<p>This will help reduce the risk of cross-contamination and keep the kitchen safe. And please wash your hands after handling raw meat! </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-when-should-you-throw-away-leftovers-92256">Health Check: when should you throw away leftovers?</a>
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</em>
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<img src="https://counter.theconversation.com/content/192723/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Enzo Palombo does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Washing raw chicken can splash bacteria around the kitchen. It’s best just to properly cook the chicken without washing it. So why do people still wash? Time to bust some chicken-washing myths.Enzo Palombo, Professor of Microbiology, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1913952022-09-28T12:32:45Z2022-09-28T12:32:45ZLouis Pasteur’s scientific discoveries in the 19th century revolutionized medicine and continue to save the lives of millions today<figure><img src="https://images.theconversation.com/files/486616/original/file-20220926-26-u8ycb1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C8764%2C5689&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Louis Pasteur was a pioneer in chemistry, microbiology, immunology and vaccinology.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/louis-pasteur-royalty-free-illustration/1176911773?adppopup=true">pictore/DigitalVision Vectors via Getty Images</a></span></figcaption></figure><p>Some of the greatest scientific discoveries haven’t resulted in Nobel Prizes.</p>
<p><a href="https://doi.org/10.1111/j.1469-0691.2012.03945.x">Louis Pasteur</a>, who lived from 1822 to 1895, is arguably the world’s best-known microbiologist. He is widely credited for the <a href="https://www.ncbi.nlm.nih.gov/books/NBK24649/">germ theory of disease</a> and for inventing the process of pasteurization – which is named after him – to preserve foods. Remarkably, he also developed <a href="https://doi.org/10.1111%2Fj.1365-2249.2012.04592.x">the rabies</a> and <a href="https://www.cdc.gov/anthrax/basics/anthrax-history.html#">anthrax</a> vaccines and made major contributions to <a href="https://www.vbivaccines.com/evlp-platform/louis-pasteur-attenuated-vaccine/#">combating cholera</a>.</p>
<p>But because he died in 1895, six years before the first <a href="https://www.nobelprize.org/">Nobel Prize</a> was awarded, that prize isn’t on his resume. Had he lived in the era of Nobel Prizes, he would undoubtedly have been deserving of one for his work. Nobel Prizes, which are awarded in various fields, <a href="https://www.nobelprize.org/the-nobel-prize-organisation/#">including physiology and medicine</a>, are not given posthumously.</p>
<p>During the current time of ongoing threats from emerging or reemerging infectious diseases, from <a href="https://www.contagionlive.com/view/virus-spillover-and-emerging-pathogens-pick-up-speed">COVID-19</a> and polio to <a href="https://theconversation.com/what-is-monkeypox-a-microbiologist-explains-whats-known-about-this-smallpox-cousin-183499">monkeypox</a> and <a href="https://doi.org/10.12703/b/9-9">rabies</a>, it is awe-inspiring to look back on Pasteur’s legacy. His efforts fundamentally changed how people view infectious diseases and how to fight them via vaccines. </p>
<p>I’ve worked in <a href="https://rodneyerohde.wp.txstate.edu/">public health and medical laboratories</a> specializing in viruses and other microbes, while <a href="https://www.health.txstate.edu/cls/">training future medical laboratory scientists</a>. My career started in virology with a <a href="https://scholar.google.com/citations?user=8XtvOZ8AAAAJ&hl=en">front-row seat to rabies detection and surveillance</a> and zoonotic agents, and it rests in large part on Pasteur’s pioneering work in microbiology, immunology and vaccinology. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/486641/original/file-20220926-8928-88tfgu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white illustration of Pasteur with a group of patients." src="https://images.theconversation.com/files/486641/original/file-20220926-8928-88tfgu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486641/original/file-20220926-8928-88tfgu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=492&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486641/original/file-20220926-8928-88tfgu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=492&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486641/original/file-20220926-8928-88tfgu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=492&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486641/original/file-20220926-8928-88tfgu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=618&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486641/original/file-20220926-8928-88tfgu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=618&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486641/original/file-20220926-8928-88tfgu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=618&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An illustration of Louis Pasteur, right, supervising the administration of the rabies vaccine at the Pasteur Institute in Paris in 1886.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-illustration-shows-french-biologist-louis-pasteur-right-news-photo/1266883710">Library of Congress/Interim Archives via Getty Images</a></span>
</figcaption>
</figure>
<h2>First, a chemist</h2>
<p>In my assessment, Pasteur’s strongest contributions to science are his remarkable achievements in the field of medical microbiology and immunology. However, his story begins with chemistry. </p>
<p>Pasteur studied under the <a href="https://www.britannica.com/biography/Jean-Baptiste-Andre-Dumas">French chemist Jean-Baptiste-André Dumas</a>. During that time, Pasteur became interested in the origins of life and worked in the field of <a href="https://www.pasteur.fr/en/institut-pasteur/history/early-years-1847-1862">polarized light and crystallography</a>. </p>
<p>In 1848, just months after receiving his doctorate degree, Pasteur was studying the properties of crystals formed in the process of wine-making when he discovered that <a href="https://www.nytimes.com/2017/06/14/science/louis-pasteur-chirality-chemistry.html">crystals occur in mirror-image forms</a>, a property known as chirality. This discovery became the foundation of a subdiscipline of chemistry known as <a href="https://doi.org/10.1002/hlca.201900098">stereochemistry</a>, which is the study of the spatial arrangement of atoms within molecules. This chirality, or handedness, of molecules was a “<a href="https://doi.org/10.1007/BF03401596">revolutionary hypothesis</a>” at the time. </p>
<p>These findings led Pasteur to suspect what would later be proved through molecular biology: All life processes ultimately stem from the precise arrangement of atoms within biological molecules.</p>
<h2>Wine and beer – from fermentation to germ theory</h2>
<p>Beer and wine were <a href="https://ageofrevolutions.com/2016/12/05/intoxication-and-the-french-revolution/">critical to the economy of France</a> and Italy in the 1800s. It was not uncommon during Pasteur’s life for products to spoil and become bitter or dangerous to drink. At the time, the scientific notion of “spontaneous generation” held that life can arise from nonliving matter, which was believed to be the culprit behind wine spoiling. </p>
<p>While many scientists tried to disprove the theory of spontaneous generation, in 1745, English biologist <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rstl.1748.0072">John Turberville Needham</a> believed he had created the perfect experiment favoring spontaneous generation. Most scientists believed that heat killed life, so Needham created an experiment to show that microorganisms could grow on food, even after boiling. After boiling chicken broth, he placed it in a flask, heated it, then sealed it and waited, not realizing that air could make its way back into the flask prior to sealing. After some time, microorganisms grew, and Needham claimed victory. </p>
<p>However, his experiment <a href="https://pubmed.ncbi.nlm.nih.gov/17940406/">had two major flaws</a>. For one, the boiling time was not sufficient to kill all microbes. And importantly, his flasks allowed air to flow back in, which enabled microbial contamination.</p>
<p>To settle the scientific battle, the French Academy of Sciences sponsored a contest for the best experiment <a href="https://doi.org/10.1080/00033798800200281">to prove or disprove spontaneous generation</a>. Pasteur’s response to the contest was a series of experiments, including a <a href="https://doi.org/10.3389%2Ffimmu.2012.00068">prize-winning 1861 essay</a>. </p>
<p>Pasteur deemed one of these experiments as “unassailable and decisive” because, unlike Needham, after he sterilized his cultures, he kept them free from contamination. By using his now famous swan-necked flasks, which had a long S-shaped neck, he allowed air to flow in while at the same time preventing falling particles from reaching the broth during heating. As a result, the flask remained free of growth for an extended period. This showed that if air was not allowed directly into his boiled infusions, then no “living microorganisms would appear, even after months of observation.” However, importantly, if dust was introduced, living microbes appeared.</p>
<p>Through that process, Pasteur not only refuted the theory of spontaneous generation, but he also demonstrated that microorganisms were everywhere. When he showed that food and wine spoiled because of contamination from invisible bacteria rather than from spontaneous generation, <a href="https://doi.org/10.3389%2Ffimmu.2012.00068">the modern germ theory of disease was born</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/OXdbQ1JkX7c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Pasteur’s discoveries resonate to this very day.</span></figcaption>
</figure>
<h2>The origins of vaccination in the 1800s</h2>
<p>In the 1860s, when the silk industry was being devastated by two diseases that were <a href="https://www.pasteur.fr/en/institut-pasteur/history/middle-years-1862-1877">infecting silkworms</a>, Pasteur <a href="https://doi.org/10.1111/j.1469-0691.2012.03945.x">developed a clever process</a> by which to examine silkworm eggs under a microscope and preserve those that were healthy. Much like his efforts with wine, he was able to apply his observations into industry methods, and he became something of <a href="https://doi.org/10.3390%2Fbiom12040596">a French hero</a>.</p>
<p>Even <a href="https://www.biography.com/scientist/louis-pasteur">with failing health</a> from a severe stroke that left him partially paralyzed, Pasteur continued his work. In 1878, he succeeded in identifying and culturing the bacterium that <a href="https://doi.org/10.3389/fimmu.2012.00068">caused the avian disease fowl cholera</a>. He recognized that old bacterial cultures were no longer harmful and that chickens vaccinated with old cultures could survive exposure to wild strains of the bacteria. And his observation that surviving chickens excreted harmful bacteria helped establish an important concept now all too familiar in the age of COVID-19 – asymptomatic “healthy carriers” can still spread germs during outbreaks.</p>
<p>After bird cholera, Pasteur turned to the prevention of <a href="https://rarediseases.org/rare-diseases/anthrax/">anthrax</a>, a widespread plague of cattle and other animals caused by the bacterium <em>Bacillus anthracis</em>. Building on his own work and that of German physician <a href="https://doi.org/10.12816/0003334">Robert Koch</a>, Pasteur developed the concept of the <a href="https://doi.org/10.3389/fimmu.2012.00068">attenuated, or weakened, versions of microbes</a> for use in vaccines.</p>
<p>In the late 1880s, he showed beyond any doubt that exposing cattle to a weakened form of anthrax vaccine could lead to what is now well known as immunity, dramatically reducing cattle mortality.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/486643/original/file-20220926-25-dha566.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A computer-generated image of the rabies virus, colored brown in this illustration and resembling a pinecone." src="https://images.theconversation.com/files/486643/original/file-20220926-25-dha566.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486643/original/file-20220926-25-dha566.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486643/original/file-20220926-25-dha566.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486643/original/file-20220926-25-dha566.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486643/original/file-20220926-25-dha566.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486643/original/file-20220926-25-dha566.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486643/original/file-20220926-25-dha566.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The deadly rabies virus. Although preventable by vaccination, rabies still kills approximately 59,000 people worldwide every year.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/rabies-virus-illustration-royalty-free-illustration/1191008423">Nano Clustering/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<h2>The rabies vaccine breakthrough</h2>
<p>In my professional assessment of Louis Pasteur, the discovery of vaccination against rabies is the most important of all his achievements. </p>
<p>Rabies has been called the “<a href="https://www.goodreads.com/book/show/13403051-rabid">world’s most diabolical virus</a>,” spreading from animal to human <a href="https://doi.org/10.12703/b/9-9">via a bite</a>. </p>
<p>Working with rabies virus is incredibly dangerous, as <a href="https://www.elsevier.com/books/rabies/wilson/978-0-323-63979-8">mortality approaches 100%</a> once symptoms appear and without vaccination. Through astute observation, Pasteur discovered that drying out the spinal cords of dead rabid rabbits and monkeys resulted in a weakened form of rabies virus. Using that weakened version as a vaccine to gradually expose dogs to the rabies virus, Pasteur showed that he could effectively immunize the dogs against rabies.</p>
<p>Then, in July 1885, Joseph Meister, a 9-year-old boy from France, was severely bitten by a rabid dog. With Joseph facing almost certain death, his mother took him to Paris to see Pasteur because <a href="https://www.pbs.org/newshour/health/louis-pasteurs-risky-move-to-save-a-boy-from-almost-certain-death">she had heard</a> that he was working to develop a cure for rabies.</p>
<p>Pasteur took on the case, and alongside two physicians, he gave the boy a series of injections over several weeks. Joseph survived and Pasteur shocked the world with a cure for a universally lethal disease. This discovery opened the door to the widespread use of Pasteur’s rabies vaccine around 1885, which <a href="https://doi.org/10.3390%2Ftropicalmed2020005">dramatically reduced rabies’ deaths in humans and animals</a>. </p>
<h2>A Nobel Prize-worthy life</h2>
<p>Pasteur once famously <a href="https://www.nhlbi.nih.gov/directors-messages/serendipity-and-the-prepared-mind">said in a lecture</a>, “In the fields of observation, chance favors only the prepared mind.” </p>
<p>Pasteur had a knack for applying his brilliant – and prepared – scientific mind to the most practical dilemmas faced by humankind.</p>
<p>While Louis Pasteur died prior to the initiation of the Nobel Prize, I would argue that his amazing lifetime of discovery and contribution to science in medicine, infectious diseases, vaccination, medical microbiology and immunology place him among the all-time greatest scientists.</p><img src="https://counter.theconversation.com/content/191395/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rodney E. Rohde has received funding from the American Society of Clinical Pathologists (ASCP), American Society for Clinical Laboratory Science (ASCLS), U.S. Department of Labor (OSHA), and other public and private entities/foundations. Rohde is affiliated with ASCP, ASCLS, ASM, and serves on several scientific advisory boards. See <a href="https://rodneyerohde.wp.txstate.edu/service/">https://rodneyerohde.wp.txstate.edu/service/</a>.</span></em></p>On World Rabies Day – which is also the anniversary of French microbiologist Louis Pasteur’s death – a virologist reflects on the achievements of this visionary scientist.Rodney E. Rohde, Regents' Professor of Clinical Laboratory Science, Texas State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1907132022-09-15T18:01:59Z2022-09-15T18:01:59ZHumans evolved with their microbiomes – like genes, your gut microbes pass from one generation to the next<figure><img src="https://images.theconversation.com/files/484929/original/file-20220915-17-nhg34h.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3840%2C2155&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The gut microbiome may also play a role in personalized medicine.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/bacteria-lactobacillus-in-human-intestine-royalty-free-image/1338810328">nopparit/iStock via Getty Images Plus</a></span></figcaption></figure><p>When the first humans moved out of Africa, they carried their gut microbes with them. Turns out, these microbes also evolved along with them.</p>
<p>The <a href="https://doi.org/10.1146/annurev-micro-090110-102830">human gut microbiome</a> is made up of hundreds to thousands of species of bacteria and <a href="https://microbiologysociety.org/why-microbiology-matters/what-is-microbiology/archaea.html">archaea</a>. Within a given species of microbe, different strains carry different genes that can <a href="https://doi.org/10.1016/j.chom.2022.08.009">affect your health and the diseases you’re susceptible to</a>. </p>
<p>There is <a href="https://doi.org/10.1016/j.cell.2019.01.001">pronounced variation</a> in the microbial composition and diversity of the gut microbiome between people living in different countries around the world. Although researchers are starting to understand what factors affect microbiome composition, such as diet, there is still limited understanding on why different groups have different strains of the same species of microbes in their guts. </p>
<p>We are researchers who study <a href="https://scholar.google.com/citations?user=KEmIhncAAAAJ&hl=en">microbial evolution</a> and <a href="https://scholar.google.com/citations?user=up7dycYAAAAJ&hl=en">microbiomes</a>. Our <a href="https://www.science.org/doi/10.1126/science.abm7759">recently published study</a> found that not only did microbes diversify with their early modern human hosts as they traveled across the globe, they followed human evolution by restricting themselves to life in the gut.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/VzPD009qTN4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The gut microbiome plays a key role in many areas of your health.</span></figcaption>
</figure>
<h2>Microbes share evolutionary history with humans</h2>
<p>We hypothesized that as humans fanned out across the globe and diversified genetically, so did the microbial species in their guts. In other words, gut microbes and their human hosts “codiversified” and evolved together – just as human beings diversified so that people in Asia look different from people in Europe, so too did their microbiomes.</p>
<p>To assess this, we needed to pair human genome and microbiome data from people around the world. However, data sets that provided both the microbiome data and genome information for individuals were limited when we started this study. Most publicly available data was from North America and Western Europe, and we needed data that was more representative of populations around the world. </p>
<p>So our research team used existing data from Cameroon, South Korea and the United Kingdom, and additionally recruited mothers and their young children in Gabon, Vietnam and Germany. We collected saliva samples from the adults to ascertain their genotype, or genetic characteristics, and fecal samples to sequence the genomes of their gut microbes.</p>
<p>For our analysis, we used data from 839 adults and 386 children. To assess the evolutionary histories of humans and gut microbes, we created <a href="https://www.khanacademy.org/science/ap-biology/natural-selection/phylogeny/a/phylogenetic-trees">phylogenetic trees</a> for each person and as well as for 59 strains of the most commonly shared microbial species.</p>
<p>When we compared the human trees to the microbial trees, we discovered a gradient of how well they matched. Some bacterial trees didn’t match the human trees at all, while some matched very well, indicating that these species codiversified with humans. Some microbial species, in fact, have been along for the evolutionary ride for over hundreds of thousands of years. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two phylogenetic trees comparing human genetic diversity across geographic regions to the genetic diversity of _Collinsella aerofaciens_" src="https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=273&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=273&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=273&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=344&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=344&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=344&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These two phylogenetic trees of human participants (left) and one bacterial species (right) closely match, indicating that they likely diversified together over the course of evolution.</span>
<span class="attribution"><a class="source" href="http://www.doi.org/10.1126/science.abm7759">Reprinted with permission from Suzuki et al., Science Volume 377, abm7759 (2022)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>We also found that microbes that evolved in tandem with people have a unique set of genes and traits compared with microbes that had not codiversified with people. Microbes that partnered up with humans have smaller genomes and greater oxygen and temperature sensitivity, mostly unable to tolerate conditions below human body temperature.</p>
<p>In contrast, gut microbes with weaker ties to human evolution have traits and genes characteristic of free-living bacteria in the external environment. This finding suggests that codiversified microbes are very much dependent on the environmental conditions of the human body and must be transmitted quickly from one person to the next, either passed down generationally or between people living in the same communities. </p>
<p>Confirming this mode of transmission, we found that mothers and their children had the same strains of microbes in their guts. Microbes that were not codiversified, in contrast, were more likely to survive well outside of the body and may be transmitted more widely through water and soil.</p>
<h2>Gut microbes and personalized medicine</h2>
<p>Our discovery that gut microbes evolved right along with their human hosts offers another way to view the human gut microbiome. Gut microbes have passed between people over hundreds to thousands of generations, such that <a href="https://doi.org/10.1126/science.aaz6827">as humans changed, so did their gut microbes</a>. As a result, some gut microbes behave as though they are part of the human genome: They are packages of genes that are passed between generations and shared by related individuals.</p>
<p><a href="https://www.genome.gov/genetics-glossary/Personalized-Medicine">Personalized medicine</a> and genetic testing are starting to make treatments more specific and effective for the individual. Knowing which microbes have had long-term partnerships with people may help researchers develop microbiome-based treatments specific to each population. Clinicians are already using <a href="https://doi.org/10.1126/scitranslmed.abk1107">locally sourced probiotics</a> derived from the gut microbes of community members to treat malnutrition.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of gut bacteria on intestinal villi." src="https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gut bacteria could be used to help treat various diseases and conditions.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/gut-bacteria-probiotics-royalty-free-image/1325237120">Artur Plawgo/iStock via Getty Images Plus</a></span>
</figcaption>
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<p>Our findings also help scientists better understand how microbes transition ecologically and evolutionarily from “free-living” in the environment to dependent on the conditions of the human gut. Codiversified microbes have traits and genes <a href="https://doi.org/10.1146/annurev.genet.41.110306.130119">reminiscent of bacterial symbionts</a> that live inside insect hosts. These shared features suggest that other animal hosts may also have gut microbes that codiversified with them over evolution.</p>
<p>Paying special attention to the microbes that share human evolutionary history can help improve understanding of the role they play in human well-being.</p><img src="https://counter.theconversation.com/content/190713/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>As early modern humans spread across the globe, their gut microbes genetically changed with them. Understanding the origins of gut microbes could improve understanding of their role in human health.Taichi A. Suzuki, Postdoctoral Research Associate in Microbiome Science, Max Planck Institute for BiologyRuth Ley, Director, Department of Microbiome Science, Max Planck Institute for BiologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1813922022-08-15T12:38:50Z2022-08-15T12:38:50ZWhich microbes live in your gut? A microbiologist tries at-home test kits to see what they reveal about the microbiome<figure><img src="https://images.theconversation.com/files/467238/original/file-20220606-13238-ocqxbp.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2305%2C1299&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">You and the trillions of microbes in your gut can live in harmony.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/bacteria-of-different-shapes-illustration-royalty-free-illustration/1359395159">Kateryna Kon/Science Photo Library via Getty Images</a></span></figcaption></figure><p>When you hear about the gut microbiome, does it ever make you wonder what tiny creatures are teeming inside your own body? As a <a href="https://scholar.google.com/citations?user=qtxpXdcAAAAJ&hl=en">microbiologist</a> who studies the microbiomes of plants, animals and people, I’ve watched public interest in gut microbes grow alongside research on their possible <a href="https://doi.org/10.1111/jgh.15728">dramatic</a> <a href="https://doi.org/10.1016/S1474-4422(19)30356-4">influence</a> on human health. In the past several years, microbiome testing techniques used by researchers like me are <a href="https://www.nytimes.com/2021/10/13/well/live/microbiome-test.html">now available to consumers at home</a>. These personal gut microbiome testing kits claim to tell you what organisms live in your gut and how to improve your gut microbiome using that data. </p>
<p>I became very interested in how these home test kits work, what kind of information they provide and whether they can really help you change your gut microbiome. So I ordered a few kits from Viome, Biohm and Floré, tried them out and sifted through my own microbiome data. Here is what I learned.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/VzPD009qTN4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Your gut microbiome can be a partner in your health – if you have the right bacteria.</span></figcaption>
</figure>
<h2>How do gut microbiome kits work?</h2>
<p>All gut microbiome kits require you to carefully collect fresh fecal material. You put it in the various tubes provided in the kit and mail the samples back to the company. Several weeks later, you’ll receive a report describing the types of microbes living in your gut and suggestions on how to change your diet or activities to potentially alter your gut microbiome.</p>
<p>What consumers don’t exactly know is how companies generate the microbial profile data from your fecal sample. A typical approach I and other microbiome researchers use is to extract and decode the microbial genetic material from a sample. We use that genetic material to identify what species of microbes are present. The challenge is that <a href="https://doi.org/10.1016/j.cgh.2018.09.017">this process can be done in many different ways</a>, and there are no widely agreed-upon standards for what is the best method.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/464112/original/file-20220518-15-2bqtdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three gut microbiome test kits (Floré, Biohm, Viome) and a roll of toilet paper displayed on a tile floor" src="https://images.theconversation.com/files/464112/original/file-20220518-15-2bqtdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464112/original/file-20220518-15-2bqtdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=587&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464112/original/file-20220518-15-2bqtdm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=587&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464112/original/file-20220518-15-2bqtdm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=587&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464112/original/file-20220518-15-2bqtdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=737&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464112/original/file-20220518-15-2bqtdm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=737&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464112/original/file-20220518-15-2bqtdm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=737&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Different home gut microbiome test kits can give conflicting results.</span>
<span class="attribution"><span class="source">Benjamin Wolfe</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>For example, microbiome analyses can be done on two types of genetic material, <a href="https://www.genome.gov/genetics-glossary/RNA-Ribonucleic-Acid">RNA</a> or <a href="https://www.genome.gov/about-genomics/fact-sheets/Deoxyribonucleic-Acid-Fact-Sheet">DNA</a>. If the profile is based on DNA, it can give you a snapshot only of what types of microbes are present, not what microbial genes are active or what activities they are doing in your body. On the other hand, if the profile is based on RNA, it can tell you not only what microbes are present, but also whether they’re playing a role in your digestion or producing metabolites that can reduce gut inflammation, among other functions. Viome <a href="https://www.viome.com/blog/why-rna-and-not-dna-how-viome-assesses-microbial-activity">generates its profiles</a> by looking at RNA, while the other companies use DNA.</p>
<p>Other data analysis choices, such as how different types of genetic sequences are sorted or which databases are used to identify the microbes, can also <a href="https://doi.org/10.1038/s41467-022-28034-z">affect the level of detail and utility</a> of the final data. Microbiome scientists are usually very careful to point out these nuances when interpreting their own data in scientific papers, but these details are not clearly presented in home microbiome kits.</p>
<h2>What I learned about my gut microbiome</h2>
<p>Though I used the same fecal sample for each kit, mixed well to ensure uniformity, I was surprised that each of the three products I tried gave me different impressions of my gut microbiome.</p>
<p>Each company gives an overall “score” on how your microbiome compares with what they consider to be “good” or “healthy.” My scores ranged from 39% (not great) to 72% (good). Interestingly, Viome, which infers microbial activity by using RNA, gave the lowest score. It noted that certain microbial activities happening in my gut, such as methane production and digestion efficiency, were not optimal.</p>
<p>I was also surprised by the variation in total microbial diversity each company reported. While there was general agreement in the overall groups of microbes present at the phylum level, a more general biological grouping, there was a huge range of variation at the species level, the most specific grouping. One company reported 527 species of microbes in my microbiome, while another reported 312. One reported only 27.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/467230/original/file-20220606-14-mt8tvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram depicting taxonomic rankings from species to kingdom" src="https://images.theconversation.com/files/467230/original/file-20220606-14-mt8tvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/467230/original/file-20220606-14-mt8tvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=525&fit=crop&dpr=1 600w, https://images.theconversation.com/files/467230/original/file-20220606-14-mt8tvp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=525&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/467230/original/file-20220606-14-mt8tvp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=525&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/467230/original/file-20220606-14-mt8tvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=660&fit=crop&dpr=1 754w, https://images.theconversation.com/files/467230/original/file-20220606-14-mt8tvp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=660&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/467230/original/file-20220606-14-mt8tvp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=660&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Organisms like microbes can be classified into groups of relatedness, from highly specific (species) to very general (kingdom).</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/classification-system-vector-illustration-royalty-free-illustration/1185111143">VectorMine/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Perhaps the most surprising finding was that my gut may harbor a microbe that could (there are many caveats here!) pose a problem for me in the future if I experience certain medical situations. Even though all companies explicitly looked for this microbe in my gut microbiome sample, only two actually found it. While I won’t name the exact microbe to protect my health privacy, I am not too worried about this result because more information, such as full genome sequencing of the microbe, is needed to better understand if this is actually a concerning strain of this microbe. But this finding does point to some surprising variation in results across different testing kits.</p>
<h2>Can this data really improve your gut microbiome?</h2>
<p>Many microbiome scientists like me would probably argue that the data these kits provide are limited in terms of giving you the power to alter your health. This is partly because gut microbiome science is still a new field with many unanswered questions. </p>
<p>One challenge is that different people can have <a href="https://doi.org/10.1038/nature11234">different proportions of microbes</a> present in their gut. This variation has made it difficult for scientists and health professionals to agree on what type of microbial community <a href="https://doi.org/10.1053/j.gastro.2020.09.057">makes a gut “healthy</a>.” Some specific species, such as the bacterium <em><a href="https://www.cdc.gov/cdiff/what-is.html">C. diff</a></em>, and some broad groups, like <a href="https://doi.org/10.1016/j.tibtech.2015.06.011">Proteobacteria</a>, are usually considered undesirable in high amounts. But there is no clear consensus on why one microbiome might be better than another.</p>
<p>Even if you did try to improve your gut microbiome based on what your gut test told you, the results might not turn out as you hoped. Probiotics or diet changes can alter the diversity of your gut microbiome and how it functions, but studies often find that each person can have different responses to these interventions, possibly because of their own <a href="https://doi.org/10.1016/j.cell.2018.08.041">unique microbiome composition</a>. The personalized ecology of gut microbial communities, combined with genetics, diet and other factors, makes it challenging to prescribe universal solutions.</p>
<p>So why bother getting a gut microbiome test? For me, it was illuminating to learn what microbes I carry around with me each day. When I eat my lunch, go for a run or get stressed out, the microbes in my gut respond to changes in my body. Researchers may not completely understand what those changes mean and how to manage our microbial partners, but getting to know who they are is a great first step.</p><img src="https://counter.theconversation.com/content/181392/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Benjamin Wolfe receives funding from the National Science Foundation and the United State Department of Agriculture.</span></em></p>The types of microbes residing in your gut can affect your mental and physical health. Home microbiome tests promise to help consumers improve the composition of their gut microbes.Benjamin Wolfe, Associate Professor of Biology, Tufts UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1808132022-04-14T05:54:03Z2022-04-14T05:54:03ZSurprise! There might be salmonella in your chocolate<figure><img src="https://images.theconversation.com/files/457864/original/file-20220413-9289-ldw894.jpg?ixlib=rb-1.1.0&rect=53%2C8%2C6000%2C3979&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/two-halves-broken-chocolate-egg-children-2126860385">Shutterstock</a></span></figcaption></figure><p>In the past three months, more than <a href="https://www.efsa.europa.eu/en/news/rapid-outbreak-assessment-multi-country-salmonella-outbreak-linked-chocolate-products">150 cases of salmonella food poisoning across Europe</a> have been linked to Kinder chocolate products. Most of the cases have been in children under ten years old.</p>
<p>Health officials have traced the outbreak to <a href="https://abcnews.go.com/Health/wireStory/eu-salmonella-outbreak-chocolate-eggs-due-bad-milk-84031934">bad milk in a factory in Belgium</a>, and many products have been <a href="https://www.foodstandards.gov.au/industry/foodrecalls/recalls/Pages/Kinder-chocolate-products-.aspx">recalled from shelves</a> as Easter approaches.</p>
<p>As consumers, we often think of the risk of food poisoning from raw or under-cooked meat, <a href="https://theconversation.com/christmas-leftovers-how-long-is-it-safe-to-keep-them-84484">leftovers</a> or even <a href="https://theconversation.com/salmonella-in-your-salad-the-cost-of-convenience-54325">packaged salad</a>. It’s less common to worry about chocolate.</p>
<h2>Salmonella outbreaks in chocolate</h2>
<p>While reports of salmonella bacteria in chocolate are not common, there have been several high-profile outbreaks. Most documented cases of salmonellosis have been in Europe and North America, perhaps because chocolate consumption is high and monitoring and surveillance is in place. </p>
<p>Outbreaks include:</p>
<ul>
<li><p>1970: cocoa powder contaminated with salmonella was used in confectionery products and subsequently caused <a href="https://pubmed.ncbi.nlm.nih.gov/4650740/">an outbreak that affected 110 people in Sweden</a></p></li>
<li><p>1973–74: 95 cases of salmonellosis, acquired from Christmas-wrapped chocolate balls, were <a href="https://www.sciencedirect.com/science/article/abs/pii/S031554637573804X">reported in Canada</a> and another 30 in the United States </p></li>
<li><p>1982–83: a salmonella outbreak involving 245 people in the United Kingdom was <a href="https://www.sciencedirect.com/science/article/abs/pii/S0140673683928222">traced to two types of chocolate bars</a> produced in Italy</p></li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/457077/original/file-20220408-20-pb8skx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/457077/original/file-20220408-20-pb8skx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/457077/original/file-20220408-20-pb8skx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457077/original/file-20220408-20-pb8skx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457077/original/file-20220408-20-pb8skx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457077/original/file-20220408-20-pb8skx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457077/original/file-20220408-20-pb8skx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457077/original/file-20220408-20-pb8skx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Salmonella outbreaks linked to chocolate.</span>
<span class="attribution"><span class="source">David Bean</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<ul>
<li><p>1985–86: 33 cases of gastroenteritis due to salmonella were <a href="https://meridian.allenpress.com/jfp/article/52/1/51/166460/An-International-Outbreak-of-Salmonella-Nima-from">reported in Canada and the US</a>, and eventually traced back to chocolate coins imported from Belgium</p></li>
<li><p>1987: 361 confirmed cases of salmonellosis in Norway and Finland were <a href="https://journals.asm.org/doi/abs/10.1128/jcm.28.12.2597-2601.1990">part of an outbreak</a> linked to chocolate contaminated with salmonella (it is estimated the actual number of infections was 20,000-40,000)</p></li>
<li><p>2001–02: an outbreak of salmonella occurred in Germany, resulting in<a href="https://bmcinfectdis.biomedcentral.com/articles/10.1186/1471-2334-5-7"> at least 439 reports of infection</a>, traced to a specific brand of chocolate distributed exclusively through a single supermarket chain</p></li>
<li><p>2006: an outbreak in the UK was <a href="https://www.eurosurveillance.org/content/10.2807/esw.11.26.02985-en">traced to chocolate</a>, with 56 cases reported.</p></li>
</ul>
<h2>Why do salmonella outbreaks occur?</h2>
<p>Chocolate begins its life as various agricultural products, the most important of which is cacao. Much of the world’s cacao comes from small farms in West Africa. </p>
<p>Beans from the cacao tree are harvested, fermented and dried on these farms. There are plenty of opportunities for the beans to become contaminated with salmonella from animals and the environment.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/salmonella-in-your-salad-the-cost-of-convenience-54325">Salmonella in your salad: the cost of convenience?</a>
</strong>
</em>
</p>
<hr>
<p>When the beans reach a chocolate factory, they are roasted. This will kill any salmonella on the beans. But if salmonella is present on the raw beans it can potentially be a source of contamination. </p>
<p>It is important raw beans are well segregated from roast beans to prevent cross-contamination. </p>
<p>As well as this segregation, chocolate factories must be well maintained and have risk-control mechanisms in place. The 2006 outbreak in the UK, for example, was ultimately linked to <a href="https://www.confectionerynews.com/Article/2006/08/02/Cadbury-contamination-proves-costly">water leaks from pipes onto chocolate</a>.</p>
<h2>Salmonella in chocolate</h2>
<p>Even when chocolate is made using appropriate food safety techniques, it has inherent properties that make it <a href="https://link.springer.com/chapter/10.1007/978-1-4939-2062-4_14">very capable of spreading bacteria</a>. </p>
<p>While salmonella will not <em>grow</em> in chocolate (there isn’t enough water), it <em>survives</em> in chocolate very well. Chocolate may even protect the salmonella during its passage through the gut. </p>
<figure class="align-center ">
<img alt="A photograph of a person pouring molten chocolate from a pot into a tray." src="https://images.theconversation.com/files/457869/original/file-20220413-9145-hvp86m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/457869/original/file-20220413-9145-hvp86m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457869/original/file-20220413-9145-hvp86m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457869/original/file-20220413-9145-hvp86m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457869/original/file-20220413-9145-hvp86m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457869/original/file-20220413-9145-hvp86m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457869/original/file-20220413-9145-hvp86m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Salmonella won’t grow in chocolate, but it survives there very well.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/production-cooking-people-concept-confectioner-filling-1283944153">Shutterstock</a></span>
</figcaption>
</figure>
<p>This means a batch of chocolate product contaminated with salmonella may remain a food safety risk for a long time and be distributed over a large geographical area. This explains why chocolate-related outbreaks can affect large numbers of people in multiple countries.</p>
<p>Another important consideration is who often consumes chocolate: children. Children are often disproportionately represented in these outbreaks and may be more susceptible to severe infections.</p>
<h2>What can be done?</h2>
<p>Most confectionery manufacturers operate under stringent guidelines to ensure quality and safety of their products. Good manufacturing processes and food safety guidelines are well established to ensure chocolate is safe. </p>
<p>Manufacturers would prefer to eliminate pathogens (disease causing microorganisms) such as salmonella in chocolate, or at least detect it during manufacturing. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/christmas-leftovers-how-long-is-it-safe-to-keep-them-84484">Christmas leftovers: how long is it safe to keep them?</a>
</strong>
</em>
</p>
<hr>
<p>However, the current Kinder recall and others like it are evidence of the system working, albeit late in the process. When a recall notice is issued, consumers should take the advice seriously.</p>
<p>So don’t put off a little Easter indulgence! In the absence of a recall notice in a specific product, it is safe to assume eating chocolate won’t make you sick – unless perhaps you over-indulge.</p><img src="https://counter.theconversation.com/content/180813/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>I previously worked at Mars as a Global Microbiology Food Safety Manager.</span></em></p><p class="fine-print"><em><span>Andrew Greenhill does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Despite the recent Kinder chocolate recall, there’s no cause for wider concern about chocolate safety.David Bean, Senior Lecturer in Microbiology, Federation University AustraliaAndrew Greenhill, Associate Professor in Microbiology and Fermentation Technology, Federation University AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1777482022-03-17T01:42:27Z2022-03-17T01:42:27ZA poo dose a day may keep bipolar away. When it comes to mental health, what else could poo do?<figure><img src="https://images.theconversation.com/files/451146/original/file-20220309-793-6zoqhi.jpg?ixlib=rb-1.1.0&rect=1%2C28%2C997%2C669&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-toilet-160277366">Shutterstock</a></span></figcaption></figure><p>In a world first, two Australians with bipolar have had poo transplants, their symptoms improved, and their cases written up in <a href="https://journals.sagepub.com/doi/abs/10.1177/0004867420912834">peer-reviewed</a> <a href="https://pubmed.ncbi.nlm.nih.gov/35165993/">journals</a>.</p>
<p>One of us (Parker) treated the second of these patients with so-called faecal microbiota transplantation, and published his case study in recent weeks. The other (Green) is part of a team recruiting people with depression to a poo transplant clinical trial.</p>
<p>We’d be the first to admit it’s early days for this type of treatment for bipolar or other mental health issues. There are many hurdles before we could see poo transplants for these become commonplace.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1500188402901159937"}"></div></p>
<p>So we do not advocate people abandon their existing medication, try this at home or demand their psychiatrist offer them a “crapsule” (a poo capsule and yes, that’s a word).</p>
<p>Yet the limited results for bipolar so far are promising. Here’s what the evidence tells us about the prospect of poo transplants for mental health.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/poo-transplants-beyond-the-yuck-factor-what-works-what-doesnt-and-what-we-still-dont-know-82265">Poo transplants beyond the yuck factor: what works, what doesn't and what we still don't know</a>
</strong>
</em>
</p>
<hr>
<h2>Let’s start with bipolar</h2>
<p>There are different types of <a href="https://theconversation.com/what-is-bipolar-disorder-the-condition-kanye-west-lives-with-143198">bipolar disorder</a>. This is when people have distinct periods of <a href="https://www.mind.org.uk/information-support/types-of-mental-health-problems/hypomania-and-mania/about-hypomania-and-mania/">mania (or a form known as hypomania)</a> – with, for example, elevated mood, increased activity and decreased sleep – and periods of depression.</p>
<p>People with bipolar usually take medication to manage their symptoms, generally for life. These medications are mainly mood stabilisers (such as lithium), but many also take antipsychotics. These medications come with risks and side effects, which depend on the medication. Side effects can include weight gain, sedation and <a href="https://library.neura.edu.au/bipolar-disorder/physical-features-bipolar-disorder/functional-changes-physical-features-bipolar-disorder/bodily-functions/motor-dysfunction-3/">movement disorders</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1288402621837893632"}"></div></p>
<h2>What happened to the two patients?</h2>
<p>In 2020, Russell Hinton, a private psychiatrist, <a href="https://journals.sagepub.com/doi/abs/10.1177/0004867420912834">described how he treated</a> the first patient. This was a woman who had tried more than a dozen different medications for her bipolar. She had been hospitalised ten times, had gained considerable weight and judged she had no quality of life.</p>
<p>After a poo transplant from her husband, she became symptom-free over the next five years, lost 33 kilograms, required no medication and her career bloomed.</p>
<p>Gordon Parker and colleagues at the University of New South Wales <a href="https://pubmed.ncbi.nlm.nih.gov/35165993/">reported their results</a> with the second patient last month. This was a young man who developed bipolar as a teenager, had tried numerous medications and became progressively intolerant of their side effects.</p>
<p>After a poo transplant, he was able to progressively cease all medications over the next year, and had virtually no mood swings. He also noted an improvement in his anxiety and ADHD (attention deficit hyperactivity disorder).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/adhd-looks-different-in-adults-here-are-4-signs-to-watch-for-178639">ADHD looks different in adults. Here are 4 signs to watch for</a>
</strong>
</em>
</p>
<hr>
<h2>How could this possibly work?</h2>
<p>Trillions of bacteria live in our guts. This so-called gut microbiome has a huge impact on our health in general, not just the health of our brain.</p>
<p>Differences in gut bacteria have been linked to <a href="https://www.nature.com/articles/s41367-019-0011-7">obesity</a>, <a href="https://www.thelancet.com/journals/ebiom/article/PIIS235239641930800-X/fulltext">diabetes</a> and <a href="https://www.gastrojournal.org/article/S0016-5085(19)34649-9/fulltext">irritable bowel syndrome</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YB-8JEo_0bI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">What is the human microbiome?</span></figcaption>
</figure>
<p>The idea behind poo transplants is to change the gut microbiome. You take poo, with all its micro-organisms, from a healthy person and give it to the one being treated.</p>
<p>You can do this “top down”, for example, by swallowing poo capsules (crapsules), or by delivering poo through a tube inserted into the nose, to the stomach or intestine. </p>
<p>Alternatively, you can insert the poo “bottom up”. You can do this with an enema, a simple, painless procedure in which a syringe transfers the poo into the rectum. Or you can use a colonoscopy, a procedure performed under a general anaesthetic involving inserting a tube higher up into the colon.</p>
<p>Poo transplants are already <a href="https://theconversation.com/poo-transplants-and-probiotics-does-anything-work-to-improve-the-health-of-our-gut-65480">used to treat</a> the often life-threatening gut infection caused by the bacterium <em>Clostridium difficile</em>.</p>
<p>They have also been trialled, with various degrees of success, in people with <a href="https://pubmed.ncbi.nlm.nih.gov/33345703/#:%7E:text=Preliminary%20data%20suggest%20that%20FMT,UC%20being%20the%20most%20compelling">irritable bowel syndrome, ulcerative colitis</a>, <a href="https://www.nature.com/articles/s41467-021-21472-1">HIV</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/32279172/">hepatitis</a>, among other medical conditions.</p>
<p>Side effects from poo transplants <a href="https://pubmed.ncbi.nlm.nih.gov/33345703/#:%7E:text=Preliminary%20data%20suggest%20that%20FMT,UC%20being%20the%20most%20compelling">are rare</a>, and usually relate to the way in which they are given, for example side effects of the anaesthetic from poo transplants delivered by colonoscopy.</p>
<h2>So how about mental health?</h2>
<p>Abnormal gut microbiomes <a href="https://www.nature.com/articles/s41380-022-01456-3">have been linked</a> to bipolar, depression and schizophrenia.</p>
<p>When poo from depressed humans is given to rats, they appear to develop a <a href="https://pubmed.ncbi.nlm.nih.gov/27491067/">rat version of depression</a>. Likewise, when mice are given poo from someone with schizophrenia, they <a href="https://www.science.org/doi/10.1126/sciadv.aau8317">develop a mouse version of schizophrenia</a>.</p>
<p>These are indirect findings. Yet they suggest poo transplants may have the potential to treat some mental health conditions.</p>
<p>So how exactly do bacteria in the gut impact mental health? There are many <a href="https://pubmed.ncbi.nlm.nih.gov/31460832/">different ways</a>, each complicated and interacting with each other. </p>
<p>For example, these bacteria act directly on the gut wall, sending signals to the brain via the vagus nerve. The bacteria also produce large quantities of chemicals (for example, <a href="https://pubmed.ncbi.nlm.nih.gov/31460832/">short-chain fatty acids</a>), which impact virtually all body systems including the immune system. We know brain function relies heavily on immune cells.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/stomach-and-mood-disorders-how-your-gut-may-be-playing-with-your-mind-50847">Stomach and mood disorders: how your gut may be playing with your mind</a>
</strong>
</em>
</p>
<hr>
<h2>Don’t try this at home</h2>
<p>At this stage, any evidence suggesting poo transplants may help people with depression or bipolar is, essentially, anecdotal.</p>
<p>Some people have tried their own version at home, involving poo donors who have not been screened for diseases.</p>
<p>One high-profile example is Dave Hosking from the Australian band Boy & Bear. He used a “<a href="https://www.rollingstone.com/music/music-features/boy-bear-dave-hosking-fecal-transplant-919384/">poo roadie</a>” to provide him with transplants on tour to help manage his depression and anxiety.</p>
<p>We wouldn’t recommend this. Poo transplants should only be carried out under the supervision of medical professionals, using an approved and thoroughly screened poo product.</p>
<p>Poo transplants are <a href="https://www.legislation.gov.au/Details/F2021C01065">tightly regulated in Australia</a>. Donations must be screened for harmful bacteria, fungi, parasites or viruses. Donors must also not have any health condition thought to be associated with gut bacteria, such as an autoimmune condition, cancer or obesity.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/boosting-your-gut-health-sounds-great-but-this-wellness-trend-is-vague-and-often-misunderstood-155472">Boosting your ‘gut health’ sounds great. But this wellness trend is vague and often misunderstood</a>
</strong>
</em>
</p>
<hr>
<h2>What happens next?</h2>
<p>We need larger, well-designed studies to show poo transplants have a real effect, and any improved symptoms cannot be explained by other factors. </p>
<p>We also need to look for markers in the microbiome that could predict a successful result. If we knew those markers, we could optimise treatment and better measure the results. </p>
<p>The first author’s centre is recruiting <a href="https://foodandmoodcentre.com.au/projects/movingmoods/">people with depression</a> to trial poo transplants. The study will randomise participants to have an enema or placebo enema. If successful, a larger study is planned. </p>
<p>In Canada, there are three such studies under way evaluating poo transplants. These are for <a href="https://pubmed.ncbi.nlm.nih.gov/34261526/">bipolar</a>, <a href="https://clinicaltrials.gov/ct2/show/NCT04805879">depression</a>, with or without <a href="https://clinicaltrials.gov/ct2/show/NCT05174273?cond=fmt&draw=8">irritable bowel syndrome</a>. </p>
<p>Though promising, we cannot conclude at this time whether poo transplants work for bipolar or depression.</p>
<p>Until the results of these studies are in, it’s too early to say if the early results with bipolar can be replicated on a larger scale.</p>
<hr>
<p><em>If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14.</em></p><img src="https://counter.theconversation.com/content/177748/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jessica Green is affiliated with:
1. Food & Mood Centre, IMPACT, Deakin University
2. Department of Psychiatry, Peninsula Health
3. Monash Alfred Psychiatry Research Centre, Monash University</span></em></p><p class="fine-print"><em><span>Gordon Parker is affiliated with the Discipline of Psychiatry and Mental Health
School of Clinical Medicine, University of New South Wales
</span></em></p>Two Australians with bipolar have been successfully treated with poo transplants, allowing them to come off, or reduce, their medications. Here’s where the science is up to.Jessica Green, PhD Candidate and Consultant Psychiatrist, Deakin UniversityGordon Parker, Scientia Professor, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1784632022-03-11T13:19:52Z2022-03-11T13:19:52ZGuns, not roses – here’s the true story of penicillin’s first patient<figure><img src="https://images.theconversation.com/files/451134/original/file-20220309-25-206ycs.jpg?ixlib=rb-1.1.0&rect=62%2C209%2C3357%2C2439&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Penicillin ushered in the antibiotics revolution, with amazing results during war and peace.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/in-1928-alexander-fleming-a-scottish-researcher-discovered-news-photo/90736822">Science & Society Picture Library/SSPL via Getty Images</a></span></figcaption></figure><p>Albert Alexander was dying. World War II was raging, and this police officer of the county of Oxford, England, had developed a severe case of sepsis after a cut on his face became badly infected. His blood was now teeming with deadly bacteria. </p>
<p><a href="https://doi.org/10.1136/bmj.289.6460.1721">According to his physician</a>, Charles Fletcher, Alexander was in tremendous pain, “desperately and pathetically ill.” The bacterial infection was eating him alive: He’d already lost one eye and had oozing abscesses all over his face and in his lungs.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/451124/original/file-20220309-28-1p5rh2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="man in 1940s police uniform" src="https://images.theconversation.com/files/451124/original/file-20220309-28-1p5rh2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/451124/original/file-20220309-28-1p5rh2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=829&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451124/original/file-20220309-28-1p5rh2n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=829&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451124/original/file-20220309-28-1p5rh2n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=829&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451124/original/file-20220309-28-1p5rh2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1041&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451124/original/file-20220309-28-1p5rh2n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1041&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451124/original/file-20220309-28-1p5rh2n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1041&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Albert Alexander in uniform.</span>
<span class="attribution"><span class="source">Courtesy of Linda Willason</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Since all known treatment options were exhausted and death appeared imminent, Fletcher decided that Alexander was the perfect candidate to try a new, experimental therapy. On Feb. 12, 1941, Alexander became the first known person to be treated with penicillin. Within days he began to make a stunning recovery.</p>
<p>I am a <a href="https://medicine.iu.edu/faculty/13502/sullivan-william">professor of pharmacology</a>, and Alexander’s story is the prelude to my yearly lecture on antibiotics. Like many other microbiology instructors, I’d always told students that Alexander’s septicemia arose after he scratched his cheek on a thorn while pruning rosebushes. This popular account dominates the scientific literature as well as recent articles and books.</p>
<p>The problem is, while descriptions of the miraculous effect of penicillin in this case are accurate, the details of Alexander’s injury were muddled, likely by wartime propaganda.</p>
<h2>Breaking the mold</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/451136/original/file-20220309-13-5iedmw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="man looking into microscope" src="https://images.theconversation.com/files/451136/original/file-20220309-13-5iedmw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/451136/original/file-20220309-13-5iedmw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=672&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451136/original/file-20220309-13-5iedmw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=672&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451136/original/file-20220309-13-5iedmw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=672&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451136/original/file-20220309-13-5iedmw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=845&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451136/original/file-20220309-13-5iedmw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=845&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451136/original/file-20220309-13-5iedmw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=845&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bacteriologist Alexander Fleming discovered antibiotic penicillin in 1928.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/alexander-fleming-scottish-bacteriologist-18-december-1943-news-photo/102730610">Daily Herald Archive/SSPL via Getty Images</a></span>
</figcaption>
</figure>
<p>The promise of penicillin as an antibiotic was first noted in 1928, when microbiologist Alexander Fleming noticed something funny in his petri dishes at St. Mary’s Hospital in London. Fleming’s cultures of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2048009/">staphylococcal bacteria did not grow well</a> on plates contaminated with a penicillium mold. Fleming discovered that the mold’s “juice” was lethal to some types of bacteria. </p>
<p>A decade later, a team of scientists led by Howard Florey at Oxford University began the arduous task of purifying the active substance from the “mold juice” and formally testing its antimicrobial properties. In August 1940, Florey and his colleagues published their striking findings that <a href="https://doi.org/10.1016/S0140-6736(01)08728-1">purified penicillin safely wiped out numerous bacterial infections</a> in mice.</p>
<p>Florey then sought Fletcher’s help to try penicillin in a human patient. That patient would be Alexander, whose death seemed inevitable otherwise. As Fletcher stated, “There was all to gain for him in a trial of penicillin and <a href="https://doi.org/10.1136/bmj.289.6460.1721">nothing to lose</a>.”</p>
<p>At the time, purified penicillin was extremely scarce, since the mold was slow to grow and yielded precious little of the drug. Despite recycling unprocessed penicillin from Alexander’s urine, there just wasn’t enough available to finish off the infection once and for all. After 10 days of improvement, Alexander gradually relapsed. <a href="https://doi.org/10.1136/bmj.289.6460.1721">He died on March 15, 1941</a>, at the age of 43.</p>
<p>Despite the tragic outcome, Alexander’s case turbocharged interest in penicillin research. As Fletcher observed, “There was <a href="https://doi.org/10.1136/bmj.289.6460.1721">no doubt about the temporary clinical improvement</a>, and, most importantly, there had been no sort of toxic effect during the five days of continuous administration of penicillin.”</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/451131/original/file-20220309-20-mcpueg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="magazine ad with drawing of wounded soldier" src="https://images.theconversation.com/files/451131/original/file-20220309-20-mcpueg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/451131/original/file-20220309-20-mcpueg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=789&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451131/original/file-20220309-20-mcpueg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=789&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451131/original/file-20220309-20-mcpueg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=789&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451131/original/file-20220309-20-mcpueg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=992&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451131/original/file-20220309-20-mcpueg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=992&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451131/original/file-20220309-20-mcpueg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=992&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An ad promoting penicillin and its role in the war effort.</span>
<span class="attribution"><a class="source" href="https://www.nlm.nih.gov/exhibition/fromdnatobeer/exhibition-making-yellow-magic.html">Schenley Laboratories, Inc. advertisement, 1944</a></span>
</figcaption>
</figure>
<p>Almost exactly a year later, on March 14, 1942, doctors in Connecticut administered the antibiotic to a woman named <a href="https://www.nytimes.com/1999/06/09/us/anne-miller-90-first-patient-who-was-saved-by-penicillin.html">Anne Miller</a> who was deathly ill with streptococcal septicemia. She made a full recovery and became the first patient cured with penicillin. <a href="https://www.washingtonpost.com/history/2020/07/11/penicillin-coronavirus-florey-wwii-infection/">Mass production of penicillin</a> became a top priority of the U.S. War Department, second only to the Manhattan Project. It is widely believed that <a href="https://us.macmillan.com/books/9780805077780/the-mold-in-dr-floreys-coat">penicillin helped the Allies during World War II</a>, preventing wound infections and helping soldiers diagnosed with gonorrhea to return to the battlefield.</p>
<h2>The rosebush tale has been a thorn in their sides</h2>
<p>Albert Alexander has earned a place in history as the first known person to be treated with penicillin for a clinical condition. Almost as famous as his name is the purported cause of death: sepsis due to a scratch from rosebushes.</p>
<p>However, an alternative explanation was revealed in a <a href="https://www.ox.ac.uk/news/science-blog/penicillin-oxford-story">2010 interview with Eric Sidebottom</a>, a historian and author of “<a href="http://www.offoxpress.com/oxford-medicine-a-walk-through-nine-centuries.html">Oxford Medicine: A Walk Through Nine Centuries</a>.” He claimed that Alexander was injured when his police station was hit during a German bombing raid on Nov. 30, 1940. Shrapnel from this attack caused the facial lacerations that led to Alexander’s fatal blood poisoning, he said.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/451127/original/file-20220309-1729-ehbqqf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="elderly woman holds up a black and white photo" src="https://images.theconversation.com/files/451127/original/file-20220309-1729-ehbqqf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451127/original/file-20220309-1729-ehbqqf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=538&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451127/original/file-20220309-1729-ehbqqf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=538&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451127/original/file-20220309-1729-ehbqqf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=538&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451127/original/file-20220309-1729-ehbqqf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=676&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451127/original/file-20220309-1729-ehbqqf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=676&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451127/original/file-20220309-1729-ehbqqf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=676&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sheila LeBlanc holding photo of her father, Albert Alexander, in 2012.</span>
<span class="attribution"><span class="source">Courtesy of Linda Willason</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Alexander’s daughter, Sheila LeBlanc, who moved to California and became an artist, confirmed Sidebottom’s account in a <a href="https://www.pe.com/2012/11/02/redlands-local-artists-share-childhood-bond/">2012 interview</a> with a local newspaper. She also revealed the grim consequences Alexander’s death had on his family. Since they’d lived in a house provided by the village, for the village constable, his death forced them to move out. LeBlanc, who was seven at the time, and her older brother were sent to an orphanage, since their mother had to find work.</p>
<p>Michael Barrett, a professor of biochemical parasitology at the University of Glasgow, also spoke to LeBlanc about the cause of Alexander’s injury. <a href="https://mosaicscience.com/story/penicillin-first-patient-history-albert-alexander-AMR-DRI/">Writing in 2018, Barrett stated</a> that while LeBlanc recalled that the constable’s house did have a beautiful rose garden, <a href="http://www.fnrcnewbury.org.uk/biography.asp?BiogID=225&PersonID=2467">her father’s fatal cut</a> was sustained during the German blitz.</p>
<p>In February 2022, I contacted Alexander’s granddaughter, Linda Willason, who is also an artist in California, to help set the record straight. Willason validated the shrapnel account and suggested that the rosebush story was “a bit of wartime propaganda.” By downplaying bombing injuries, the government likely hoped to maintain the public’s stiff upper lip.</p>
<p>While the nature of Alexander’s injury may seem a trivial detail, correcting the historical record is important. Alexander died in the line of duty, and the apocryphal rosebush story obscures his honorable actions. His descendants are hopeful the true account of his injury will now eclipse the false one.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/450839/original/file-20220309-27-pxnrfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="blue plaque with white text on brick wall" src="https://images.theconversation.com/files/450839/original/file-20220309-27-pxnrfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/450839/original/file-20220309-27-pxnrfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450839/original/file-20220309-27-pxnrfz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450839/original/file-20220309-27-pxnrfz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450839/original/file-20220309-27-pxnrfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450839/original/file-20220309-27-pxnrfz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450839/original/file-20220309-27-pxnrfz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A plaque dedicated in 2021 shares the real story of Alexander’s injury.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Albert_Alexander_plaque.jpg">Newbury Town Council/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>In 2021, <a href="https://www.bbc.com/news/uk-england-berkshire-57208267">a plaque commemorating Alexander</a> was installed in Newbury that reads: “On war support duty in Southampton on 30th November 1940, Albert was injured in an air raid. Contracting staphylococcal and streptococcal septicaemia, he was transferred to the Radcliffe Infirmary in Oxford, where he was selected for the first clinical application of penicillin. … His place in the history of antibiotics is secure.”</p>
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<p class="fine-print"><em><span>Bill Sullivan does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Albert Alexander was the first known person treated with penicillin. While his ultimately fatal case is well known in medical histories, the cause of his illness has been misattributed for decades.Bill Sullivan, Professor of Pharmacology & Toxicology, Indiana University School of MedicineLicensed as Creative Commons – attribution, no derivatives.