Superbugs in Canadian chicken? Yes, and US too

CBC News, the Canadian national TV network, has caused a stir in the food-blog world with the results of a nationwide investigation that found antibiotic-resistant bacteria contaminating supermarket chicken. In its words:

Chicken bought at major supermarkets across Canada is frequently contaminated with superbugs — bacteria that many antibiotics cannot kill — an investigation by CBC TV’s Marketplace has found.

Marketplace researchers — along with their colleagues at Radio-Canada’s food show L’Epicerie — bought 100 samples of chicken from major grocery chains in Vancouver, Toronto and Montreal… The 100 samples were sent to a lab for analysis. Two-thirds of the chicken samples had bacteria. That in itself is not unusual — E. coli, Salmonella and Campylobacter are often present in raw chicken.

What was surprising was that all of the bacteria uncovered during the Marketplace sampling were resistant to at least one antibiotic. Some of the bacteria found were resistant to six, seven or even eight different types of antibiotics.

“This is the most worrisome study I’ve seen of its kind,” said Rick Smith, the head of Environmental Defence, a consumer advocacy group.

I haven’t had time to watch the full program, but no question I think this kind of reporting is worth doing. Nothing brings the threat of agricultural antibiotic use home to people like showing them that resistant bacteria are living on the meat they might have brought home last night.

One important point, though: Don’t think for a moment this is just a Canadian problem.

Last month, a team from the University of Ioannina in Greece analyzed in Foodborne Pathogens and Disease 428 samples of various retail meats they bought in northwest Greece over three years:

E. coli from chicken exhibited high rates of resistance to ciprofloxacin (62.5%) followed by lamb/goat (10.9%), pork (15.7%), and beef (27.9%) meat. Resistance to nitrofurantoin dominated in the lamb/goat isolates (60%). Resistance to tetracycline predominated in pork (68.2%) and chicken (62.5%), and resistance to aminoglycosides dominated in lamb/goat meat isolates. S. aureus resistance to clindamycin predominated in lamb/goat isolates (50%), whereas resistance to ciprofloxacin predominated in the pork strains, but no resistance to methicillin was observed. Of the enterococci isolates 21.1% were resistant to vancomycin. High resistance to ampicillin (96%) was observed in Y. enterocolitica and all of the C. jejuni isolates were resistant to ampicillin, cephalothin, and cefuroxime. These results indicate that meat can be a source of resistant bacteria, which could potentially be spread to the community through the food chain.

Last year, a team from the University of Iceland found fluoroquinolone-resistant E. coli passing from chickens to humans there (the drug Cipro is a fluoroquinolone, and the human isolates were Cipro-resistant), a multi-institution team from Canada found resistance to third-generation cephalosporins in Salmonella enterica spreading from chicken meat to humans, and the Irish quasi-governmental group SafeFood released a long report (and hosted a conference) on “The Problem of Antimicrobial Resistance in the Food Chain.” And of course MRSA ST398, the strain of drug-resistant staph that arose in food animals, has now been found in retails meats across the EU.

Oh, but none of those countries are the United States, you say. Then take a look at these:

Those graphics come from a little-read report put out every year by the US Food and Drug Administration as part of its participation in NARMS, the National Antimicrobial Resistance Monitoring System that’s shared by the FDA, USDA and CDC. The FDA handles the part of NARMS that looks for resistant bacteria in meat (CDC does human illnesses, USDA does live animals), and the figures above show the percentages of Salmonella and enterococci that were found in retail chicken breasts between 2002 and 2008 (the most recent report) and were resistant to various drugs. The bar along the bottom of each figure shows the major drug classes. So in 2008: 45% of Salmonella on chicken were resistant to tetracycline and 30% to penicillins; among enterococci (common gut bacteria, and therefore common contaminants of meat during slaughtering), 65% resistant to tetracycline and more than 90% to lincosamides, which include the everyday drug clindamycin.

In the narrative portion of the report, the FDA said:

38.2% of chicken breast Salmonella isolates were resistant to ≥ 3 antimicrobial classes in 2008 compared to 51% in ground turkey, an increase in both from previous years. From 2002–2007, multidrug resistance to ≥ 3 antimicrobial classes ranged from 20–34.4% among chicken breast and 20.3–42.6% for ground turkey. More than 15% of chicken breast and ground turkey isolates showed resistance to ≥ 4 classes in 2008.

So, just to underline: Multi-drug resistant superbugs aren’t only on chicken in Canada; if you buy chicken in the United States, they are more than likely on your chicken too.

And whatever country they are occurring in, the solution is the same. Drug-resistant bacteria in food won’t diminish until we reduce the amount of drugs that food animals receive while they are raised.

Update: At Grist’s Meat Wagon, Tom Philpott very kindly points out that I actually broke the news of the latest NARMS report, which I didn’t realize (it was a busy day; see my next post for why). Apparently the report was posted to the FDA web site on Dec. 17, but neither of us can find any evidence that it was publicized, such as a press release on the FDA’s press site. His larger point is important:

We find out from the report that the FDA has been monitoring the situation since 2002 — and finding plenty of antibiotic-resistant strains on meat sold directly to consumers. And they’ve been sharing the information with other leading regulatory/public health agencies — but not so much to the people they’re supposed to be protecting and informing: i.e., us. … six weeks since the FDA report and a year since Sharfstein’s testimony [in 2010, promising scrutiny by the Obama adminsitration – m.], policy hasn’t moved at all. Where are the loud public statements from the FDA trumpeting the fact that our factory farms are cooking up superbugs that make their way to our meat? Where’s the USDA on this topic, which is supposed to protect the public from tainted meat? Where’s CDC?



Leave a Reply

Your email address will not be published. Required fields are marked *