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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #413660

Research Project: Intestinal Microbial Ecology and Non-Antibiotic Strategies to Limit Shiga Toxin-Producing Escherichia coli (STEC) and Antimicrobial Resistance Transmission in Food Animals

Location: Food Safety and Enteric Pathogens Research

Title: Carriage and gene content of pesi-Like plasmids in Salmonella enterica serovar infantis from swine

item Villanueva, Paul
item BRADSHAW, DAVID - Oak Ridge Institute For Science And Education (ORISE)
item Bearson, Bradley - Brad
item Bearson, Shawn
item Anderson, Christopher

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Salmonella enterica serovar Infantis (S. Infantis) has steadily increased over the last decade to one of the most prevalent Salmonella serotypes from poultry sources in the United States. A megaplasmid of emerging S. Infantis (pESI) encodes genes that may confer a competitive advantage in a poultry host, and as a result, pESI is now observed in a majority of poultry-associated S. Infantis isolates. Further, pESI contains several antibiotic resistance and virulence genes linked to increased human pathogenicity, making it a public health concern. S. Infantis is one of the top five most prevalent serovars isolated from swine; however, pESI carriage and genomic characterization have not been investigated for swine-associated S. Infantis. Annotation of pESI core genes in S. Infantis isolated from swine-associated samples by the Food Safety and Inspection Service identified 57 S. Infantis harboring pESI from 2016-2022. The proportion of S. Infantis with pESI isolated from comminuted pork increased from ~2% in 2017 to ~16% in 2022. A pangenome analysis of pESI from swine-associated S. Infantis isolates and 245 representative pESI genomes from chicken-associated S. Infantis revealed no statistically significant differences in overall pESI genomic composition or average presence of individual genes between the two animal sources. Among the swine-associated pESI, gene content significantly differed based on year, with pESI gene profiles becoming more diverse over time. The gene composition of pESI did not differ based on geographical region or isolation source. Principal coordinates analysis based on the pESI genomic content identified subgroups of swine-associated pESI with different genomic profiles. In particular, one pESI subgroup increased in prevalence in 2021-2022 and had a significantly higher presence of key genes, including the glnALG operon, mobA/B, and the higA/higB toxin/antitoxin system. Our findings suggest that pESI in S. Infantis warrants further monitoring in the swine industry, and interventions targeting S. Infantis may be necessary to prevent a similar increase in swine pESI carriage over time, as observed in poultry.