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Vapour from e-cigarettes makes MRSA bacteria more aggressive

Smoking weakens the immune system and lowers the ability of human cells to fight infection – research has shown this over and over again. Smoking cigarettes, and breathing in second-hand smoke, puts people…

Second thoughts? Nicolasnova, CC BY-NC

Smoking weakens the immune system and lowers the ability of human cells to fight infection – research has shown this over and over again. Smoking cigarettes, and breathing in second-hand smoke, puts people at risk for developing severe lung and respiratory track infections. Smokers are two to four times more likely to develop pneumococcal pneumonia than non-smokers. Cigarette smoking also increases the rates and severity of influenza infection and increases the risk of tuberculosis.

But what if the problem isn’t just that cigarette smoke weakens the immune system, but actually makes the bacteria more aggressive?

Antibiotic resistant bacteria are a growing problem worldwide. MRSA (Methicillin Resistant Staphylococcus aureus) is one of the most common, causing thousands of deaths every year. About 20% of people are colonised by MRSA, and the nasal passages are the most common site for these bacteria to live. Because this organism inhabits an area that is exposed to inhaled substances and is a common cause of invasive disease, we began studying it in the lab. I hypothesised that cigarette smoke would put stress on bacterial cells, just as it does on human cells, and that the bacteria would respond by protecting and arming themselves.

Our research, recently presented at the American Thoracic Society’s international conference in San Diego, has found that cigarette smoke increases the resistance of MRSA to being killed by a host’s immune cells. In particular, cigarette smoke induced resistance to antimicrobial peptides – substances produced by human cells, which kill bacteria like antibiotics do.

As the e-cigarette market boomed, I wondered if e-cigarette vapour would have the same effects, so we ran parallel studies on the effects of it on MRSA virulence. We have found over the past few months that both regular cigarette smoke and e-cigarette vapour make drug-resistant bacteria more virulent. We have not yet pinpointed the components of e-cigarette vapour that trigger these effects, but preliminary findings suggest that the nicotine in e-juice (the liquid used in e-cigarettes that is vapourised and inhaled) is a significant contributor.

Regular cigarette smoke has more than 5,000 components and nicotine is a small part of this. E-cigarette vapour has many fewer components, so it could mean that nicotine plays a bigger role in the effect we see on MRSA. E-cigarette users take in two to 20 times the amount of vapour in volume, and thus nicotine, than normal smoke. This is because it is so easy to keep inhaling from an e-cigarette – it can keep going for the equivalent of a whole pack of cigarettes, doesn’t make your clothing or breath smell, and can be vaped indoors. This means that vapers are dramatically increasing their intake of nicotine, and therefore increasing the exposure of their colonising bacteria to this substance.

Like cigarette smoke, e-cigarette vapour exposure also weakens our host defences, making it easier for bacteria to cause invasive infections. This means that the vapour is influencing bacteria to be more aggressive and harder to kill, and suppressing the ability of our own cells to attack and kill bacteria.

MRSA in particular is spreadable to other people via touch. There have been outbreaks on school sports teams for example. It is an aggressive bug, so it can cause disease in healthy people as well as the infirm. It already has antibiotic resistance, so making it even more resistant to antimicrobials and killing by host cells is a dangerous thing. It can be incredibly hard to clear MRSA infections, and we are running out of antibiotics powerful enough to eliminate it.

It is hard to believe that anything could be as bad as cigarette smoke. But we simply don’t know enough about the effects of vapour to be able to say that it is a lesser evil. But as best as we can tell from the data we have, e-cigarette vapour is not benign. In fact, it appears that e-cigarette vapour both makes bacteria tougher to kill and weakens the immune system. Together these early findings suggest that people who vape are at increased risk of developing serious bacterial infections.

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13 Comments sorted by

  1. Ron Maverick

    logged in via Facebook

    "The virulence of MRSA is increased by e-cigarette vapor," said lead investigator Laura E. Crotty Alexander

    What kind of vapor? Ratio of PG to VG? Nicotine content or non-nicotine? Cig-alike or APV?

    -"However, she added, the vapor did not make the bacteria as aggressive as cigarette smoke exposure did in parallel studies her group conducted."

    -"e-cigarettes may not be as bad as tobacco, they still have measurable detrimental effects on health."

    OK, so Im not exposed to 6000 chemicals…

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  2. Ron Maverick

    logged in via Facebook

    "The virulence of MRSA is increased by e-cigarette vapor," said lead investigator Laura E. Crotty Alexander

    What kind of vapor? Ratio of PG to VG? Nicotine content or non-nicotine? Cig-alike or APV?

    -"However, she added, the vapor did not make the bacteria as aggressive as cigarette smoke exposure did in parallel studies her group conducted."

    -"e-cigarettes may not be as bad as tobacco, they still have measurable detrimental effects on health."

    OK, so Im not exposed to 6000 chemicals…

    Read more
    1. biochemistri.es

      logged in via Twitter

      In reply to Ron Maverick

      No deaths, but plenty of poisonings. From the NYT: http://nyti.ms/1eDp7kz

      “Of the 74 e-cigarette and nicotine poisoning cases called into Minnesota poison control in 2013, 29 involved children age 2 and under. In Oklahoma, all but two of the 25 cases in the first two months of this year involved children age 4 and under.”

      Harm reduction possibly, this is part of the trouble though ‒ there's just not enough long-term studies with it being a new product. Nicotine is a toxin, and carcinogenicity…

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    2. Ron Maverick

      logged in via Facebook

      In reply to biochemistri.es

      Granted, there has been too many children getting into potentially hazardous substances. One is too many in a perfect world.
      I fully support education and child resistant caps on e-liquids. Honestly I don't know anyone who doesn't. But we are now talking about parental responsibility.
      Most of the numbers I have seen about calls to poison control centers has been for inquiries, not poisonings.
      Are you aware that there are an average 20,000 poisonings per year from toothpaste? Thats an average…

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    3. Ron Maverick

      logged in via Facebook

      In reply to biochemistri.es

      Nicotine is a toxin, and carcinogenicity of ‘vaping’ produced compounds looks possible –

      If you set up to run the experiments to fit the results you want to see, anything is possible..
      To obtain the elevated levels of formaldehyde to equal a traditional cigarette, the coil had to be heated to 800K (Kelvin). Normal e-liquid is vaporized at approx. 400K..
      As a vaper and former analog smoker, I would rather take a drag off a Marlboro than get a dry hit at even 500.. And I cant stand the smell of normal cigs anymore...

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  3. biochemistri.es

    logged in via Twitter

    While I don't doubt this has all been carried out with a clean ethical slate, and nicotine is a potent toxin, headlines like these are snapped up by the media (it's reached the Daily Mail already), and I just don't know if scientists should do so before peer review!

    Not wishing to put a downer on any of this, it'd just be easy to have confounding factors is all.

    I've read up on e-cigarette research myself, and tried to collect some of the biomedical literature's thoughts on the topic at http://biochemistri.es/post/84151472401 which I'll add this piece onto.

    Very glad to see further research going on, e-cigs really have sprung up shockingly fast. Hopefully your group might be able to publish a preprint soon? I'd love to read some details.

    Also kudos for choice of stock photo, a lot of the results for "e-cigarette" are very clean-looking if not quite glossy representations, which I'd argue aid their sellers' marketing efforts.

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  4. Clive Bates

    logged in via Twitter

    A few questions:

    1. Could you provide a link to the published peer reviewed article?

    2. In a different report of this work (http://www.medicalnewstoday.com/articles/276912.php), it points out that cigarette smoke is far worse:

    "Although the e-cigarette vapor increased the resistance of this pathogen, which is potentially lethal to humans, the virulence of MRSA was even greater when exposed to conventional cigarette smoke. The surface charge alterations in the bacteria were 10 times greater…

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  5. Steven Crook

    Programmer and software designer at Currently resting

    There's a fairly common thread running through all of the Conversation articles on E-Cigarettes, They're completely bad and should at the very least be strictly licensed even if a ban isn't possible

    Of course they may be right, but it's the certainty with which the information is presented that bothers me. It looks like more of the new puritanism.

    I'm not entirely happy with the idea of feeding an addiction for nicotine, but if you've got addicts, you might as well give them the safest possible environment to feed their addiction.

    I'm reminded of the arguments against providing needle exchanges for IV drug users...

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  6. k d

    logged in via Twitter

    Interesting, but there’s a key inaccuracy: "E-cigarette users take in two to 20 times the amount of vapour in volume, and thus nicotine” (which is the correlation is not causation fallacy).

    If one sits there vaping high nicotine vapour all day, one gets nicotine overdose symptoms which are idiosyncratic but generally unpleasent (e.g. tiredness headache). Thus ecig users tend to low dose nicotine (3-8mg/ml) fairly quickly. It's also clear from research that cigarettes are tuned to optimise…

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  7. Judith Olney

    Ms

    This is all very interesting, despite the inaccuracies, but I'm left wondering what real world applications this type of research would have, apart from being used as anti-ecigarette propaganda?

    As a vaper, (I switched from smoking tobacco to using a personal vapouriser), I have found that my immune system is much stronger, I have much less illness, in fact I have not been ill in anyway since making the switch, and any small wounds etc, heal a great deal faster, which as far as I can see means that…

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  8. VAPE Australia

    logged in via Twitter

    Looking at the Australian organisations that support 'The Conversation', I am gob smacked by the lack of attention to detail and research. Since when did CSIRO support blatantly poor reporting and research?

    Well, perhaps all of the funding cuts are starting to take their toll.

    One of the components of e-liquid is PG, which is used as a disinfectant. It is also found in NRT products which are inhaled. If you want to have a crack at e-cigs, then you better have a crack at all of the manufacturers…

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    1. Bill Budd

      Lecturer, Researcher

      In reply to VAPE Australia

      The headline to this article probably should really have read; "E-cigarettes 10 times safer than tobacco cigarettes!" since the researchers found MRSA virulence was 10 times greater for tobacco smoke compared with vapour (see: http://www.eurekalert.org/pub_releases/2014-05/ats-emb051214.php).

      Unfortunately the "study" referred to in this article is not published in a peer-reviewed journal but an unpublished abstract from a conference presentation. So more of a scientific press release really and…

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