Location: Meat Safety & Quality ResearchTitle: Food service pork chops from three U.S. regions harbor similar levels of antimicrobial resistance regardless of antibiotic use claims
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2019
Publication Date: 10/1/2019
Citation: Vikram, A., Miller, E., Arthur, T.M., Bosilevac, J.M., Wheeler, T.L., Schmidt, J.W. 2019. Food service pork chops from three U.S. regions harbor similar levels of antimicrobial resistance regardless of antibiotic use claims. Journal of Food Protection. 82(10):1667-1676. https://doi.org/10.4315/0362-028x.jfp-19-139.
Interpretive Summary: Meat products, including pork chops, are commonly thought to transmit antibiotic resistance from animals to humans. Pork chops produced from swine “raised without antibiotics” (RWA) are assumed to harbor lower levels of antibiotic resistance than “conventional” (CWA) products which may contain meat from animals that received antibiotics. However, for pork products this assumption is not based on scientific evidence. Only two studies have examined antibiotic resistance levels in U.S. pork products. Both studies only tested for 1 antibiotic resistant bacterium and found similar levels in CONV and RWA pork. This study found similar levels in CONV and RWA pork chops for all 8 antibiotic resistant bacteria and 10 antibiotic resistance genes assessed. These results provide some of the first evidence that antimicrobial uses in U.S. swine production do not significantly impact the antibiotic resistance present in pork products.
Technical Abstract: Pork products from animals “raised without antibiotics” (RWA) are assumed to harbor lower levels of antimicrobial resistance (AMR) than conventional (CONV) pork products with no claims regarding use of antimicrobial agents during production. A total of 372 pork chop samples from CONV (n¼190) and RWA (n¼182) production systems were collected over 13 months from three food service suppliers. The following bacteria were cultured: Escherichia coli, tetracycline-resistant (TETr) E. coli, third-generation cephalosporin-resistant (3GCr) E. coli, Salmonella enterica, TETr Salmonella, 3GCr Salmonella, nalidixic acid–resistant Salmonella, Enterococcus spp., TETr Enterococcus, erythromycin-resistant Enterococcus, Staphylococcus aureus, and methicillin-resistant S. aureus. Production system did not significantly impact the detection of cultured bacteria (P . 0.05). Metagenomic DNA was isolated from each sample, and equal amounts of metagenomic DNA were pooled by supplier, month, and production system for 75 pooled samples (38 CONV, 37 RWA). Quantitative PCR was used to assess the abundances of the following 10 AMR genes: aac(60)-Ie-aph(200)-Ia, aadA1, blaCMY-2, blaCTX-M, blaKPC-2, erm(B), mecA, tet(A), tet(B), and tet(M). For all 10 AMR genes, abundances did not differ significantly (P . 0.05) between production systems. These results suggest that use of antimicrobial agents during swine production minimally impacts the AMR of bacteria in pork chops.