Prevalence of antibiotic-resistant enterobacteriaceae isolated from chicken and pork meat purchased at the slaughterhouse and at retail in Bavaria, Germany

Abstract

The purpose of this study was to investigate chicken and pork meat sampled at the slaughterhouse and at retail for differences in the presence of antibiotic resistant Gram-negative bacteria. For this aim, Escherichia coli (n=677), Enterobacter spp. (n=167), Citrobacter spp. (n=83), Serratia spp. (n=116), Klebsiella spp. (n=125), and Salmonella spp. (n=89) were isolated from 500 chicken and 500 pork samples purchased at the slaughterhouse and at retail (in the same amounts) in Germany. Salmonella were present in 17% of the chicken, and in 0.4% of the pork meat samples. There was a clear shift in the spectrum of coliforms from slaughterhouse to retail: Enterobacter, Citrobacter and Klebsiella were the most frequently detected coliforms (other than E. coli) from slaughterhouse samples, whereas the prevalence of Serratia spp. was up to eight times higher in retail samples. The prevalence of E. coli was higher in slaughterhouse samples, whereas the prevalence of other coliforms and Salmonella spp. was higher in retail samples. E. coli strains were often resistant to penicillins, streptomycin, spectinomycin, doxycycline and sulfamethoxazole/trimethoprim. Resistance rates of the other coliforms were generally low. Resistant and multi-resistant isolates were significantly more common in chicken meat. Compared to samples from the slaughterhouse, the prevalence of resistant bacteria tended to be higher in retail samples, probably due to good conditions for resistant bacteria on the matrix meat and/or due to secondary contamination with resistant strains. Therefore, stringent hygiene measures should be observed to reduce the risk of transmission of resistant bacteria from food to humans.