Prevalence and Antimicrobial Resistance of Salmonella Isolates from Retail Meats in Indiana, USA

The prevalence of antimicrobial-resistant Salmonella in retail meats raises food safety and public health concerns. In this study, we report our collaborative work with the National Antimicrobial Resistance Monitoring System (NARMS) and the FDA's Laboratory Flexible Funding Model (LFFM) cooperative agreement program in sampling and testing of Indiana retail meats. A total of 200 ground meat samples (turkey, beef, and pork) were collected from retail stores across the state of Indiana between September 2022 and June 2024 and screened for Salmonella according to the FDA's NARMS Retail Meat Surveillance protocol. Five Salmonella isolates were recovered from ground turkey - including a multidrug-resistant Salmonella enterica serovar Infantis, and serovars Reading and Litchfield. Two Salmonella isolates were recovered from ground pork - serovars I 4,[5],12:i:- and London - and one Salmonella isolate was recovered from ground beef - serovar I 4,[5],12:i:-. Salmonella prevalence and antimicrobial susceptibility data were compared with the NARMS national trends. Whole-genome sequencing identified antimicrobial resistance genes and one mutation, conferring resistance to six classes of antimicrobial drugs, in agreement with phenotypic antimicrobial susceptibility testing. Heavy metal tolerance genes were also identified. Seven of the eight Salmonella isolates matched clinical isolates deposited at the National Center for Biotechnology Information. This collaborative work successfully expanded the hallmark NARMS antimicrobial resistance surveillance program to the state of Indiana.