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Study Examines Bacteria, Resistance in Retail Meats

20 May 2013

US - Raw poultry and beef are potential reservoirs of antibiotic-resistant Enterobacteriaceae, according to a new study from Tennessee State University.

The study on the evaluation of drug-resistant Enterobacteriaceae in retail poultry and beef by A. Kilonzo-Nthenge, E. Rotich and S.N. Nahashon shows there has been increasing concern on the emergence of multidrug-resistant foodborne pathogens from foods of animal origin, including poultry.

Their investigation, published in Poultry Science, demonstrates that raw poultry and beef are potential reservoirs of antibiotic-resistant Enterobacteriaceae

The 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:H7.

Two hundred thirty-seven samples representing 95.2 per cent of the total of 249 samples tested were positive for Enterobacteriaceae. The level of contamination with Enterobacteriaceae in raw meats ranged from 3.26 log10 colony forming units (cfu) per gramme to 4.94 log10cfu per 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 log10cfu per g, respectively) than ground turkey and chicken wings (3.26 and 3.26 log10cfu per 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 per cent, respectively.

Resistance of the Enterobacteriaceae to antimicrobials was most frequent with erythromycin, penicillin and ampicillin at 100, 89 and 65.8 per cent, respectively.

Few (2.7 per cent) of the Enterobacteriaceae were resistant to chloramphenicol.

Salmonella spp., E. coli O157:H7, Morganella morganii, Yersinia enterocolitica and Vibrio parahemolyticus exhibited multiple drug resistance.

The Tennessee-based investigators concluded that raw poultry and beef are potential reservoirs of antibiotic-resistant Enterobacteriaceae.


Kilonzo-Nthenge A., E. Rotich and S.N. Nahashon. 2013. Evaluation of drug-resistant Enterobacteriaceae in retail poultry and beef. Poult. Sci. 92(4):1098-1107. doi: 10.3382/ps.2012-02581

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