The FSIS NARMS (National Antimicrobial Resistance Monitoring System) published a Multiyear Report evaluating trends in Salmonella serotypes and antimicrobial resistance (AMR) in certain food animal species and products sampled from 2014 through 2019 as part of FSIS NARMS sampling. Salmonella isolates were analyzed by serotyping and antimicrobial susceptibility testing (AST) to evaluate differences in sample source and slaughter class (chicken, turkey, cattle, and swine). The top Salmonella serotypes in the cecal (intestinal) and product samples for each slaughter class remained the same throughout the study: Kentucky (chicken), Reading (turkey), Montevideo (cattle), and Anatum (swine).
The serotype Infantis emerged as one of the top serotypes in chicken in both cecal (21%) and product samples (15%). Most of the Salmonella from cecal samples among all slaughter classes were not resistant to any antimicrobials tested over the 6 years. Multidrug resistant (MDR) Salmonella gradually increased over time in both cecal and product samples, with a significant increase in product samples from 2016 to 2019. Serotype Infantis emerged as a major contributor to the increase in MDR Salmonella in chicken. Salmonella susceptibility to ciprofloxacin significantly decreased among isolates from cecal and product samples. Cephalosporin-resistant Salmonella increased over time in product samples from cattle and swine. Salmonella isolates showed a significant increase in resistance to ciprofloxacin, ceftriaxone, and trimethoprim-sulfamethoxazole.
