Identification of Plasmid-Mediated Quinolone Resistance in SalmonellaIsolated from Swine Ceca and Retail Pork Chops in the United States

ABSTRACTFluoroquinolones are important antimicrobial drugs used to treat human Salmonellainfections, and resistance is rare in the United States for isolates from human and animal sources. Recently, a number of Salmonellaisolates from swine cecal contents and retail pork products from National Antimicrobial Resistance Monitoring System (NARMS) surveillance exhibited decreased susceptibility to ciprofloxacin. We identified two qnrB19quinolone resistance plasmids that are predominantly responsible for this phenomenon and found them distributed among several Salmonellaserotypes isolated throughout the United States.