Evaluation of drug-resistant Enterobacteriaceae in retail poultry and beef

There has been increasing concern on the emergence of multidrug-resistant foodborne pathogens from foods of animal origin, including poultry. The current study aimed to evaluate antibiotic-resistant Enterobacteriaceae from raw retail chicken/turkey parts (thigh, wings, breast, and ground) and beef meat (ground and chunks) in Middle Tennessee. Resistance of the collected Enterobacteriaceae to a panel of antibiotics was determined by the Kirby-Bauer disk diffusion test. Retail meats were also assayed for the presence of Salmonella spp. and Escherichia coli O157:II7. Two hundred thirty-seven samples representing 95.2% of the total of 249 samples tested were positive for Enterobacteriaceae. The level of contamination with Enterobacteriaceae in raw meats ranged from 3.26 log(10) cfu/g to 4.94 log(10) cfu/g with significant differences in counts among meat types (P < 0.05). Contamination was significantly greater (P < 0.05) in ground beef, beef chucks, ground chicken, chicken breast, and turkey wings (4.92, 4.58, 4.94, 4.75, 4.13 log(10) cfu/g, respectively) than ground turkey and chicken wings (3.26 and 3.26 log(10) cfu/g, respectively). Klebsiella oxytoca, Serratia spp., E. coli, and Haffnia alvei were most prevalent contaminants at 27.4, 14.3, 12.1, and 11.4%, respectively. Resistance of the Enterobacteriaceae to antimicrobials was most frequent with erythromycin, penicillin, and ampicillin at 100, 89, and 65.8%, respectively. Few (2.7%) of the Enterobacteriaceae were resistant to chloramphenicol. Salmonella spp., E. coli O157:II7, Morganella morganii, Yersinia enterocolitica, and Vibrio parahemolyticus exhibited multiple drug resistance. This investigation demonstrates that raw poultry and beef are potential reservoirs of antibiotic-resistant Enterobacteriaceae.