Differences in the prevalence and antimicrobial resistance among non-typhoidal Salmonella serovars isolated from retail chicken meat across the United States of America, 2013–2020

The emergence of antimicrobial-resistant non-typhoidal Salmonella (NTS) in retail chicken meat poses a food safety risk. Data on antimicrobial resistance (AMR) in NTS isolates collected by the National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) from retail chicken meat across the United States of America between 2013 and 2020 were analyzed. A total of 3,067 samples tested positive for NTS. The most common NTS serovars were S. Kentucky (n = 1,088), S. Infantis (n = 587), S. Enteritidis (n = 475), and S. Typhimurium (n = 424), respectively. A significant increasing trend in the proportion of S. Infantis and a decreasing trend for S. Typhimurium has been observed. High-proportion clusters were detected in the northeast and southeast of the United States of America for S. Typhimurium and in the west coast and southeast for S. Kentucky. Multidrug resistance (resistance to at least three antimicrobial classes) was common in S. Infantis and S. Typhimurium isolates, while S. Enteritidis isolates were mainly pan-susceptible. The predicted probability of resistance to beta-lactam antibiotics (ampicillin and ceftriaxone), sulfonamides (sulfisoxazole), and quinolones (nalidixic acid) were highest in S. Infantis isolates, while S. Kentucky isolates showed the highest probability of resistance to aminoglycosides (streptomycin) and tetracyclines. Differences in the geographical distribution of NTS serovars and variations in their AMR patterns warrant serovar-specific antimicrobial stewardship programs.