Antimicrobial Resistance and Genomic Characterization of Salmonella Serovars Typhimurium and 4,[5],12:i:- in Huzhou, China.

OBJECTIVE

serovar Typhimurium (. Typhimurium) and its monophasic variant, 4,[5],12:i:-, have become two of the most frequently isolated serovars worldwide, in both humans and animals. This study investigated the antimicrobial resistance and genomic characteristics of these two serovar .

METHODS

Between 2021 and 2023, a total of 90 . Typhimurium and 4,[5],12:i:-were collected from clinical and food samples in Huzhou. Their antimicrobial resistance phenotype and genes, virulence genes, and phylogenetic relationship were analyzed.

RESULTS

4,[5],12:i:-, which all belong to ST34, has become the main serotype of isolated in Huzhou instead of . Typhimurium. Notably, we observed a higher incidence of infections among the young population (<5 years old). The 90 isolates were mainly resistant to tetracycline (94.4%), ampicillin (72.2%), and trimethoprim/sulfamethoxazole (70.0%), with multidrug resistance (MDR) rates as high as 93.3%. Genome sequencing indicated that these isolates possessed 39 antimicrobial resistance genes and 184 virulence genes.

CONCLUSION

This research enhances our understanding of . Typhimurium and 4,[5],12:i:- infections, which is helpful to guide clinical responses.