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.