tag:theconversation.com,2011:/uk/topics/bacterial-pathogens-56199/articlesBacterial pathogens – The Conversation2019-09-05T18:49:13Ztag:theconversation.com,2011:article/1229412019-09-05T18:49:13Z2019-09-05T18:49:13ZBugs and bores: a source of dangerous bacteria in remote communities’ water supply<figure><img src="https://images.theconversation.com/files/291064/original/file-20190905-175691-teqoga.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C613%2C344&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bores with high iron content can be a haven for disease-causing bacteria.</span> <span class="attribution"><span class="source">Mirjam Kaestli</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A study of three remote community water supplies in northern Australia, <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0007672">published today in the journal PLOS Neglected Tropical Diseases</a>, revealed that bores with high levels of iron were more likely to harbour <em>Burkholderia pseudomallei</em>, the bacterium that causes the potentially fatal disease melioidosis in both <a href="http://www.nature.com/articles/nmicrobiol20158">humans</a> and <a href="https://www.nejm.org/doi/full/10.1056/NEJMra1204699">animals</a>, than bores with low iron levels.</p>
<p>The study, by researchers from Charles Darwin University and <a href="https://www.menzies.edu.au">Menzies School of Health Research</a>, reveals the challenge of delivering safe water to remote communities in Australia’s wet-dry tropics, many of which rely on bore water from shallow aquifers. But we also found that treating water with chlorine is an effective way to improve its safety.</p>
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<a href="https://theconversation.com/getting-clean-drinking-water-into-remote-indigenous-communities-means-overcoming-city-thinking-106701">Getting clean drinking water into remote Indigenous communities means overcoming city thinking</a>
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<p>Based on a modelling study, melioidosis causes an estimated <a href="http://www.nature.com/articles/nmicrobiol20158">89,000 deaths worldwide</a>, and people with <a href="https://www.ncbi.nlm.nih.gov/pubmed/21152057">diabetes, chronic lung or renal disease or hazardous alcohol use</a> are particularly at risk. Deaths due to contaminated drinking water have been documented in <a href="http://www.ajtmh.org/content/journals/10.4269/ajtmh.2001.65.177">Northern Australia</a> and <a href="https://wwwnc.cdc.gov/eid/article/20/11/14-0832_article">Thailand</a>, where <em>B. pseudomallei</em> is endemic.</p>
<p><em>B. pseudomallei</em> is found naturally in soil and surface water in rural areas around Darwin. Around <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3381386/">one-third</a> of tested unchlorinated residential bores were positive for this bacterium, and it has also been found in <a href="https://www.ncbi.nlm.nih.gov/pubmed/10653571">aerator sprays and tank sludge from water treatment plants</a>.</p>
<p>Water can usually be made safe by treating it with chlorine, although in laboratory experiments some <em>B. pseudomallei</em> strains can <a href="https://www.researchgate.net/publication/9078159_The_effect_of_free_chlorine_on_Burkholderia_pseudomallei_in_potable_water">tolerate higher chlorine levels</a> than others.</p>
<p>There is also an association between <em>B. pseudomallei</em> and increased <a href="https://researchers.cdu.edu.au/en/publications/association-of-the-melioidosis-agent-burkholderia-pseudomallei-wi">iron levels in bore water</a>. Naturally occurring iron-cycling bacteria can metabolise the iron, producing bacterial films inside pipes that contribute to corrosion and reduce bore yield. The problem with biofilms is that opportunistic pathogens in water supplies such as <em>Legionella pneumophila</em> or <em>Pseudomonas aeruginosa</em> can also colonise the biofilms, protecting the bacteria from chlorination.</p>
<p>Many aquifers in Northern Australia contain naturally high levels of iron, and some are also shallow and prone to inundation with surface water during the wet season. This iron-rich source water potentially compromises the water in the distribution system. </p>
<h2>Putting bores to the test</h2>
<p>The problem is that we know very little about the microbiology of drinking water in remote communities. To learn more, we studied three remote water supplies in the Top End with varying iron levels: one low, one medium, and one high. </p>
<p>The “high iron” community had water with an average of 0.8mg of iron per litre – more than double the threshold of 0.3mg/L suggested by the <a href="https://www.nhmrc.gov.au/about-us/publications/australian-drinking-water-guidelines">Australian drinking water guidelines</a> above which the taste of water is affected. </p>
<p>The “medium iron” community had water with average iron concentrations of 0.25mg/L, while the figure for the “low iron” community was 0.05mg/L. </p>
<p>All three communities had reported melioidosis cases over recent decades: three cases since 1994 in the high-iron community; 11 in the medium-iron community; and four in the low-iron community. It is not known where these patients acquired the melioidosis bacteria.</p>
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<a href="https://images.theconversation.com/files/291065/original/file-20190905-175678-bgtf0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291065/original/file-20190905-175678-bgtf0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291065/original/file-20190905-175678-bgtf0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291065/original/file-20190905-175678-bgtf0i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291065/original/file-20190905-175678-bgtf0i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291065/original/file-20190905-175678-bgtf0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291065/original/file-20190905-175678-bgtf0i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291065/original/file-20190905-175678-bgtf0i.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>
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<span class="caption">Sampling a high-iron bore.</span>
<span class="attribution"><span class="source">Mirjam Kaestli</span>, <span class="license">Author provided</span></span>
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<p>For each community, together with collaborators<a href="https://www.powerwater.com.au/">Power and Water Corporation</a>, we sampled water from five points along the drinking water distribution system, of which three were unchlorinated (bores and tanks), and two were from the chlorinated reticulation system. We then used genetic sequencing to survey the bacterial communities in water.</p>
<p>We found that the geochemistry of the groundwater had a substantial impact on the types of bacteria in untreated water, particularly in the case of bacteria that can metabolise iron. </p>
<p>We found <em>B. pseudomallei</em> in bores with high iron levels, and in a bacterial biofilm inside a bore pipe which also contained iron-oxidising <em>Gallionella</em>, nitrifying <em>Nitrospira</em>, and free-living <em>Hartmannella</em> amoebae, which <a href="https://iai.asm.org/content/68/3/1681.short?cited-by=yes&legid=iai;68/3/1681">may be able to harbour <em>B. pseudomallei</em></a>. </p>
<h2>Growing challenge</h2>
<p>If <em>B. pseudomallei</em> occurs inside amoebae growing in remote communities’ source water, this could make it harder to <a href="https://cmr.asm.org/content/17/2/413">successfully target the bacteria using chlorination</a>. Second, the interaction with <em>Gallionella</em> bears further scrutiny because this iron-oxidising bacterium is increasingly used in biological iron-removal filters.</p>
<p>In our samples we detected three pathogen groups: non-tuberculous mycobacteria, <em>Pseudomonas aeruginosa</em>, and <em>B. pseudomallei</em>. Importantly, <em>B. pseudomallei</em> was found in water with scarce nutrients. This highlights the fact that this bacterium can <a href="https://aem.asm.org/content/82/24/7086.short">thrive under nutritionally poor conditions</a> (it has been known to survive even in distilled water for up to <a href="https://www.ncbi.nlm.nih.gov/pubmed/21764093">16 years</a>). This in turn means when water providers routinely monitor the water supply integrity by using heterotrophic bacteria counts, they might not suspect the presence of <em>B. pseudomallei</em> as the former cannot survive under such nutrient scarce conditions.</p>
<p>Surprisingly, we also found <em>B. pseudomallei</em> in a bore accessing a deeper aquifer. We will need to investigate further across all seasons to determine whether this bacterium does indeed live in deeper, confined aquifers, or whether it is mainly linked to intrusions of surface water during the wet season. The latter would be easier for water providers to manage. </p>
<p>We detected no <em>B. pseudomallei</em> in treated water, although we did find abundant DNA of another opportunistic pathogen group: non-tuberculous mycobacteria.</p>
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Read more:
<a href="https://theconversation.com/some-remote-australian-communities-have-drinking-water-for-only-nine-hours-a-day-86933">Some remote Australian communities have drinking water for only nine hours a day</a>
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<p>Our study provides a first snapshot of the bacteria in a selection of remote water supplies, and can hopefully contribute to improved management of water supplies in the wet-dry tropics.</p><img src="https://counter.theconversation.com/content/122941/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mirjam Kaestli has received funding from Power and Water Corporation (NT), the ARC and the NHMRC.</span></em></p><p class="fine-print"><em><span>Karen Gibb has received funding from Power and Water Corporation (NT).</span></em></p>Many remote communities in Australia’s north rely on bore water. But a new microbiology analysis suggests that the chemistry of untreated water can allow disease-causing bacteria to grow unchecked.Mirjam Kaestli, Research Fellow, Charles Darwin UniversityKaren Gibb, Professor, Charles Darwin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1213222019-08-02T12:07:52Z2019-08-02T12:07:52ZWe found reservoirs of antibiotic resistant bacteria across London<figure><img src="https://images.theconversation.com/files/286735/original/file-20190802-117853-h6gblt.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5062%2C3372&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/baker-street-london-uk-january-29-1299936133?src=hMB0p500T2jTrzpZa5XNAw-1-53&studio=1">Larry Platner/Shutterstock</a></span></figcaption></figure><p>The human body houses a wide range of bacteria, both inside and out. One is <em>Staphylococcus epidermidis</em> – a happy resident of our skin that does no harm. But if transferred inside the body on an implanted artificial hip, that once friendly skin bacteria can cause a major infection. </p>
<p>Other species in the same family of bacteria can cause mild to life-threatening infections. These are opportunistic pathogens – they can take advantage of a weakened immune system and cause serious harm. </p>
<p>We recovered a total of 600 bacteria from this family around East and West London. They represented 11 different species and were collected from surfaces that people often touch, including ATMs, lift buttons, escalator rails and door handles in the London Underground, shopping centres and general public areas in hospitals.</p>
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<img alt="" src="https://images.theconversation.com/files/286720/original/file-20190802-117903-1t74kaf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286720/original/file-20190802-117903-1t74kaf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286720/original/file-20190802-117903-1t74kaf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286720/original/file-20190802-117903-1t74kaf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286720/original/file-20190802-117903-1t74kaf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286720/original/file-20190802-117903-1t74kaf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286720/original/file-20190802-117903-1t74kaf.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">Ticket machines in the London Underground were sampled for bacteria.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/london-uk-november-2017-tourists-commuters-756111727?src=gOHr3xu9yGYDSl1FapjijA-1-45&studio=1">Paolo Paradiso/Shutterstock</a></span>
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<p>Out of the 600 bacteria we found, nearly half were multidrug resistant, meaning they were immune to treatment from several types of antibiotics.</p>
<p>Antimicrobial resistance is one of the most important public health threats worldwide. Every year, <a href="https://amr-review.org/sites/default/files/AMR%20Review%20Paper%20-%20Tackling%20a%20crisis%20for%20the%20health%20and%20wealth%20of%20nations_1.pdf">more than 700,000 people die</a> from infections that can’t be treated with antibiotics, as they’ve been rendered ineffective by multidrug resistant bacteria. </p>
<h2>Reservoirs of antibiotic resistance</h2>
<p><a href="https://www.nature.com/articles/s41598-019-45886-6">In our study</a>, all of the bacteria showed at least some resistance to 11 common antibiotics used to treat infections today. More than 80% of the bacteria were immune to treatment with <a href="https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/flemingpenicillin.html">penicillin</a> and <a href="https://www.nature.com/articles/193987a0">fusidic acid</a> – some of the first antibiotics to be discovered and among the oldest still used.</p>
<p>Resistance was less prevalent in newer antibiotics – more than half of the bacteria tested were resistant to erythromycin and just over a quarter were resistant to amoxicillin, tetracycline, oxacillin and cefoxitin.</p>
<p>Although public areas in East and West London harboured high levels of antibiotic resistant bacteria, we found more of them in East London (56.7%) compared to West London (49.6%), probably because more people live closer together in East London than West London.</p>
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<a href="https://theconversation.com/antibiotic-resistant-superbug-genes-found-in-the-high-arctic-110636">Antibiotic resistant 'superbug' genes found in the High Arctic</a>
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<p>So why should we be worried if “friendly” bacteria are becoming resistant to the treatments we’ve depended on for decades? Well, we also found lots of different genes which encode resistance to different antibiotics within these bacteria. These were capable of “jumping” from one bacteria to another, meaning multidrug resistance could spread to human pathogens and potentially create “superbugs” that our present arsenal of antibiotics can’t treat. </p>
<p>Bacteria can transfer these genes using plasmids – little DNA loops which bacteria of the same or different species can swap between themselves like bracelets. When bacteria acquire multiple plasmids, they’re effectively loaded with resistance to multiple drugs.</p>
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<img alt="" src="https://images.theconversation.com/files/286721/original/file-20190802-117910-1vyt4fh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286721/original/file-20190802-117910-1vyt4fh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286721/original/file-20190802-117910-1vyt4fh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286721/original/file-20190802-117910-1vyt4fh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286721/original/file-20190802-117910-1vyt4fh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286721/original/file-20190802-117910-1vyt4fh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286721/original/file-20190802-117910-1vyt4fh.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">Ineffective antibiotics fail to halt the spread of resistant bacteria.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/antimicrobial-susceptibility-testing-petri-dish-648642895?src=j7u1gOZbnjVJwFjoZlRfnQ-1-29&studio=1">Jarun Ontakrai/Shutterstock</a></span>
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<p>Our research suggests that the places we pass through and the surfaces we touch everyday may be reservoirs for these multidrug resistant bacteria. The fact that there are such high levels of antibiotic resistance within and outside hospitals – where antibiotic use is concentrated – suggests that bacteria may be moving between the two. </p>
<p>This is disturbing. It suggests that infection control in hospitals and public areas may be failing to eradicate the problem. As always, good hand hygiene and better public cleanliness could be the best protection.</p>
<p>We’re undertaking more tests to find out where these bacteria came from and which other species they’re related to. They may have originated with bacteria recovered from hospital patients or from livestock or pets. Antibiotic resistance has been called a global threat <a href="https://www.theguardian.com/society/2019/apr/29/antibiotic-resistance-as-big-threat-climate-change-chief-medic-sally-davies">as serious as climate change</a>. It will require a concerted global response to tackle it.</p><img src="https://counter.theconversation.com/content/121322/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hermine Mkrtchyan 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>The scale of antibiotic resistance among bacteria found on surfaces around London is exposed in our new study.Hermine Mkrtchyan, Senior Lecturer in Biomedical Sciences, University of East LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/990712018-07-03T04:46:04Z2018-07-03T04:46:04ZNew gene transfer rules could help prevent spread of antibiotic resistance<figure><img src="https://images.theconversation.com/files/225832/original/file-20180702-116123-1hiva8n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bacteria exchange genes easily, but a newly discovered set of rules that regulate these exchanges could help us to prevent the spread of antibiotic resistance.</span> <span class="attribution"><span class="source">from www.shutterstock.com</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Unlike other organisms, bacteria can take up genetic material from their environment. This ability to exchange genes enables them to pick up new traits such as different metabolic pathways, virulence genes and antibiotic resistance.</p>
<p>Better understanding of the complex mechanisms of gene transfer may be the key for holding the line against the global threat of <a href="http://www.who.int/news-room/fact-sheets/detail/antibiotic-resistance">increasing antibiotic resistance</a>. Our <a href="http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007421">latest findings</a> have taken us step closer to this goal by uncovering a new set of rules. </p>
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Read more:
<a href="https://theconversation.com/antibiotics-before-birth-and-in-early-life-can-affect-long-term-health-97778">Antibiotics before birth and in early life can affect long-term health</a>
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<h2>Bacterial genomes doing what we cannot</h2>
<p>Bacteria are our constant and ubiquitous companions. Teeming throngs of bacteria shimmy around on every surface and their collective biomass is <a href="http://www.pnas.org/content/early/2018/05/15/1711842115">more than a thousand times bigger</a> than that of the entire human population.</p>
<p>We would not survive for long without bacteria. We owe them for making our planet habitable and for their role in returning nutrients to the soil. Earth without microbes is a <a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002020">nightmare scenario</a>. However, the evolutionary processes that allow bacteria to survive in conditions that are off limits to other lifeforms can also make them detrimental to human health. </p>
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Read more:
<a href="https://theconversation.com/why-are-some-e-coli-deadly-while-others-live-peacefully-within-our-bodies-95499">Why are some _E. coli_ deadly while others live peacefully within our bodies?</a>
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<p>Unlike the human genome, which remains relatively unadulterated during our lifetimes, bacteria acquire new genetic material frequently. Some of the bacteria around you have changed since you began reading this. </p>
<p>While our own genetic material is tucked away behind the protective membranes of a nucleus, bacteria have no such vault-like structure. A single bacterium can have <a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0030130">acquired as much as 60% of its genome</a> recently through a phenomenon called <a href="https://www.ncbi.nlm.nih.gov/pubmed/14617137">horizontal gene transfer</a> (HGT), where large swaths of DNA can be swapped in or completely replaced in a single step. </p>
<h2>The conundrum</h2>
<p>The mystery around <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(11)00101-1">HGT</a> is that the processes by which it chops and changes DNA seem at first glance to be haphazard, and yet HGT tends to take place <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3191353/">most frequently between closely related species</a>. Why?</p>
<p>Horizontal gene transfer can happen in a few different ways. Each of them boils down to a bit of DNA being introduced into the bacterial cell, right next to the cell’s own DNA, and being accidentally <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4536854/">incorporated into the chromosome</a>. Regardless of how the DNA ends up inside that cell, the introduced DNA can be included in the genome of the recipient cell. No gene appears to be <a href="https://www.sciencedirect.com/science/article/pii/S1369527405001219">immune</a>. </p>
<p>If the story were simple, that would be it. The cell with the new DNA would face natural selection by competing for resources with other local microbes. If the DNA contained genes that are beneficial this might mean new abilities for the cell, like surviving the next local antibiotic apocalypse. </p>
<p>However, biology is rarely so simple. Rather, bacteria that are more closely related tend to give and receive genes more frequently than one might expect. Part of the reason that this is surprising is that the most likely candidates for donating genes in any environment are not close relatives. As many as 18,000 separate bacterial genomes can be found in <a href="https://www.nature.com/articles/nrmicro1160.pdf">a single gram of soil</a>. This suggests that something other than proximity determines what gene transfer events are successful. </p>
<h2>The rules</h2>
<p>At the core of our work are short, repeated sequences called AIMS, or <strong>A</strong>rchitecture <strong>IM</strong>parting <strong>S</strong>equences. AIMS are important during DNA <a href="https://link.springer.com/article/10.1007/s00239-005-0192-2">replication and DNA segregation in bacteria</a>. </p>
<p>We discovered that if sets of AIMS are well matched between a donor and recipient genome, then the DNA moving between those genomes can be maintained. The opposite is true if they are not well matched, effectively establishing the “rules of transfer”.</p>
<p>In nature, incoming DNA rains down on a bacterial chromosome. The AIMS of a recipient cell act a bit like a holey umbrella that only lets AIMS compatible DNA through to be added to the chromosome. The patterns of inversions (random events in which a chunk of DNA is turned around to face the opposite direction) and HGT in bacterial chromosomes suggests that natural selection has filtered out the bacteria in which HGT with non-compatible AIMS had taken place. </p>
<p>It is worth mentioning that AIMS are not a hard barrier, but rather a constraint on HGT that positively enforces transfer between closely related organisms. While our results suggest that the wrong AIMS may cause problems for important systems like DNA replication and segregation, newly acquired genes that are game changers for the cell, like antibiotic resistance genes, are unlikely to be filtered out if they have incompatible AIMS. Like much in biology, AIMS based rules are another piece of a more complicated puzzle. </p>
<h2>Making it work in our favour</h2>
<p>Plasmids are tiny loops of double stranded DNA that float in the cell and are able to replicate independent of the bacterial chromosome. This makes them immune to AIMS associated constraints on gene transfer; they don’t have to enter the chromosome. They are one way that novel DNA can end up in the cell.</p>
<p>They are also often loaded with antibiotic resistance genes. If we can find ways of making these plasmids just a little more unbearable for the bacteria in the environment, perhaps we can limit their spread in the same way that AIMS limit transfer between bacterial chromosomes. </p>
<p>One idea would be a genetic tool that would force plasmids to physically integrate with chromosomes. This would simultaneously make these less mobile and subject them to the constraints that chromosomes function under. For example, a plasmid “immobilisation” cassette could be deployed in high-risk areas to reduce plasmid-based gene transfer in a group of multi-drug resistant disease-causing bacteria known as the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4871955/pdf/BMRI2016-2475067.pdf">ESKAPE pathogens</a>. </p>
<p>If we can do that, perhaps in the future we can prevent the spread of genes we are worried about, like antibiotic resistance genes or virulence genes.</p><img src="https://counter.theconversation.com/content/99071/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Heather Hendrickson 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>The discovery of molecular rules that regulate the transfer of genetic material between bacteria could help prevent the spread of antibiotic resistance.Heather Hendrickson, Senior Lecturer in Molecular Bioscience, Massey UniversityLicensed as Creative Commons – attribution, no derivatives.