E. coli, Vegetarians, and Resistance, Oh My!

How antibiotic resistant your E. coli are has to do with where you’ve been, not what you eat.

A recent study isolated E. coli from 567 newly hospitalized patients and 100 vegetarians (one E. coli isolate per person), and screened them for resistance to X antibiotics, including ciprofloxacin, nalidixic acid, trimethoprim-sulfamethoxazole (the primary treatment for E. coli-related urinary tract infections), ceftriaxone, and ceftazidime (the last two indicate the presence of an extended-spectrum beta-lactamase, and can only be reliably treated with carbapenems).
The only significant risk factors for being resistant to one or more drugs were travel outside the U.S. and ICU admission within the previous twelve months. For trimethoprim-sulfamethoxazole resistant E. coli, the only thing associated with resistance was foreign travel. Diet or contact with farm animals had no effect.
One goofy thing is that vegetarians are more likely to travel outside the U.S., giving them higher carriage rates of resistant E. coli (although this has nothing to do vegetarianism as far as I can tell).
So what does this mean? One thing that I keep seeing in the literature (and which will be the subject of a future post) is that the frequency of resistance outside of high-use settings has little to do with antibiotic use per se, but with clonal dynamics. That is, resistance increases or decreases in frequency because certain bacterial clones (clusters of very closely related genotypes) which happen to be resistant are changing in frequency. Resistance is essentially a ‘hitchhiker’ on some poorly understood population dynamics.
Of course, this only highlights the importance of limiting antibiotic use: the more genetic backgrounds that resistance is found in, the more likely that one or more of the genetic backgrounds will become frequent, making infections from these organisms harder to treat.
Cited article: Sannes MR, Belongia EA, Kieke B, Smith K, Kieke A, Vandermause M, Bender J, Clabots C, Winokur P, Johnson JR. 2008. Predictors of Antimicrobial-Resistant Escherichia coli in the Feces of Vegetarians and Newly Hospitalized Adults in Minnesota and Wisconsin. J Infect Dis. 2008 Feb 1;197(3):430-434.

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8 Responses to E. coli, Vegetarians, and Resistance, Oh My!

  1. Mike: I think this finding makes sense. In U.S. access to antibiotics is controlled through prescriptions. Outside the U.S., you can purchase antibiotics, without a prescription, in any drug store. It seems likely that if antibiotics are more readily available, you will find that a larger fraction of the human gut bacteria, like E. coli, will be resistant.
    There may be some differences in terms of veterinary use outside of the U.S., too, but I don’t know much about that.

  2. Sandra,
    I agree with you completely. What is interesting though, is the lack of any noticeable transmission through the food chain.

  3. Gwenny says:

    So vegetarians travel more than us carnivores? (Well, anyone travels more that I do, I log less than 100 miles a week getting two folks to work every day.) So much for their “We are better for the environment claim”, huh? LOL

  4. What if there’s something in our diet that’s so ubiquitous that we don’t detect it that easily?
    Say – small numbers E. coli, or commensal bacteria on a variety of foods that can transmit the necessary plasmids? Or even, DNA itself. I remember a study that Julian Davies did where his lab found the DNA for antibiotic resistance genes in preparations of antibiotics.
    That’s all wild speculation of course, but the genes have to get in your gut somehow.

  5. Sandra,
    If the food chain is important, it’s not jumping out of the data. My own take on this is that agriculture serves as a way to generate novel resistant strains, but that spread of these resistant clones from the agriculture setting is rather limited and slow. Hopefully, as our ability to rapidly and thoroughly (i.e., lots of sequence) type strains will be able to track things better.

  6. That’s one great thing about the Next Gen DNA sequencing technologies. It won’t be long and we’ll be sequencing everything.

  7. Christina Schwanitz says:

    Sandra wrote:
    “I think this finding makes sense. In U.S. access to antibiotics is controlled through prescriptions. Outside the U.S., you can purchase antibiotics, without a prescription, in any drug store.”
    I wonder which country is that supposed to be, because it’s just blatantly wrong. But of course it sounds good, in a vaguely American xenophobic “all bad things are foreign” way.
    Funny thing is, I remember reading articles in the SPIEGEL news magazine here in Germany about the rise of resistant bacterial strains in hospitals all over the worlds, and how it’s a far bigger problem in the USA than in Europe. I don’t know the number of the print source anymore, but let’s see, even a quick Google search found this:
    “It is also worth noting that American doctors prescribe antibiotics more often than doctors in many other countries (German doctors are reportedly very reluctant to prescribe them for anything other than serious conditions). The European Union does not allow the prophylactic use of antibiotics in livestock that is the norm in this country.”
    Which is true, Germans are somewhat paranoid about eating meat from animals shot up with antibiotics (or eating anything derived from transgenic plants), and “taking pills” for a non-serious non-chronical illness is frowned upon. Many people here have a (resonable or unreasonable) belief in naturopathy, steam baths, etc. For most common ailments, the doctor will prescribe something to alleviate the symptoms but mostly prescribe bed rest and fresh air, thank you.
    So something else is going on here.

  8. tiret says:

    very thanks for article

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