Salmonella enterica and Escherichia coli harboring bla _CMY in retail beef and pork products

We estimated the proportion of retail beef and pork products containing bla _CMY-mediated third-generation cephalosporin resistance in commensal Escherichia coli and Salmonella enterica. Samples were obtained from 50 grocery stores located in two U.S. states. From each store, 20 fresh meat products were purchased, including 7 packages of ground beef, 3 packages of beef steak, 6 packages of pork chops, and 4 packages of pork ribs. The resulting 1000 packages of fresh meat product were individually screened for the presence of E. coli or Salmonella harboring bla _CMY. Over 8% of all retail meat packages contained E. coli with bla _CMY, whereas 4% contained Salmonella and only 0.5% contained Salmonella with bla _CMY. Retail pork products more frequently yielded E. coli with bla _CMY than did beef products (12.2% vs. 4.0%; p=0.06). Salmonella were also recovered more frequently from pork than beef (5.8% vs. 2.4%; p<0.01). In addition, all five Salmonella isolates with bla _CMY were recovered from pork products. Our data suggest that enteric bacteria carrying bla _CMY are frequently present in fresh retail meat products. However, we did not quantify the number of resistant bacteria present in these products, which makes the public health implications of this result unclear.