According to a new study by the Translational Genomics Research Institute (TGen), the meat you buy at the supermarket has a significant chance of being contaminated by bacteria, and a slightly lower but not insignificant chance of being contaminated by multiple drug-resistant bacteria.
How did the researchers discover this? Simple. They went out, bought some meat, and tested it, as this press report describes. Specifically, researchers at TGen collected 136 samples of beef, chicken, poultry and turkey (covering 80 brands) from 26 retail grocery stores in Los Angeles, Chicago, Fort Lauderdale, Flagstaff, and Washington, DC. (Side note: how did they pick these five cities? They seem kind of random...maybe they had friends there?) (Second side note: in case you were wondering about what specific cuts of meat, the (open access!) article published on this study in Clinical Infections Diseases specifies that the beef was ground, the chicken in the form of breasts and thighs, the pork both in chops and ground form, and the turkey ground and in cutlets).
Anywho, they bought this meat and then they did some fancy scientist stuff and looked for bacteria (specifically staphylococcus aureus). And oh, did they find it! (Third side note: I do NOT recommend Google-imaging "staphylococcus aureus." Cannot. Unsee.) (Fourth side note: Staph infections kill more people than AIDS in the US). (Fifth and final side note: the large portion of killer staph infections are picked up in hospitals, not from meat.)
Back to the point. As NPR reports, of the samples tested "47 percent had evidence of Staphylococcus aureus (S. aureus) contamination. More than half of the bacteria they found were resistant to at least three classes of antibiotics."
I actually read through the four-page source study in Clinical Infections Diseases and it gives the breakdown of S. aureus contamination by meat type. First comes turkey (77% of samples were contaminated), followed by pork (42%), chicken (41%), and beef (37%). NINETY-SIX PERCENT of the S. aureus bits discovered were "resistant to at least 1 antimicrobial," including most commonly tetracycline, ampicillin, penicillin, and erythromycin, but also quinupristin/dalfopristin, fluoroquinolones, oxacillin, daptomycin, and vancomycin.
Multi-drug resistant strains of S. aureus--defined as "intermediate or complete resistance to 3 or more antimicrobial classes"--were "common," and was most prevalent among turkey, followed by pork, beef, and chicken. In total, 52% of the S. aureus isolates they found were multi-drug resistant.
Because there were distinct strands of the bacteria on each different kind of meat, it suggests that food animals are the predominant source of contamination, not human handling after the fact. This is not particularly surprising. To quote the authors of the study, "Conventional concentrated animal feeding operations (CAFOs) provide all the necessary components for the emergence and proliferation of multidrug-resistant zoonotic pathogens."
Now, before you panic and stop eating meat, the authors concede that "the public health relevance" of their study is "unclear," and as NPR notes, "most Staph found in meat can be eliminated by cooking food thoroughly." Nevertheless, "it can still pose a risk to consumers if handled unsafely or if it cross-contaminates with other things in the kitchen." And we in America should all be a at least a little bit worried, because we eat a ton of meat. And our meat eats a ton of antibiotics, as this chart demonstrates (chart taken from here, data from the FDA):
More thoughts about the way we make meat, a topic I am sure I will come back to, can be found here and here. More about antibiotic resistance here.
Until the next dispatch, be sure to cook your meat just a little more than you think is necessary.
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