Food Service Pork Chops from Three U.S. Regions Harbor Similar Levels of Antimicrobial Resistance Regardless of Antibiotic Use Claims.

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 ( = 190) and RWA ( = 182) production systems were collected over 13 months from three food service suppliers. The following bacteria were cultured: tetracycline-resistant (TET) third-generation cephalosporin-resistant (3GC) TET 3GC nalidixic acid-resistant spp., TET erythromycin-resistant and methicillin-resistant . Production system did not significantly impact the detection of cultured bacteria ( > 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: , , , (B), (A), (B), and (M). For all 10 AMR genes, abundances did not differ significantly ( > 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.