Prevalence and genomic insights into Yersinia enterocolitica in Southeastern China (2008-2022).

Yersinia enterocolitica is a significant foodborne pathogen causing gastrointestinal illnesses worldwide. This study investigates the prevalence and genomic characteristics of Y. enterocolitica to assess potential health risks in southeastern China, a region lacking mandatory yersiniosis monitoring. From 2939 samples collected between 2008 and 2022, 105 isolates were recovered. The highest prevalence was found in rodents (8.1%), followed by retail meats (7.1%), other foods (3.7%), and human clinical cases (0.8%). In addition to meats and rodents, ready-to-eat salads, seafood, and frozen food products were identified as potential transmission vehicles. Various bioserotypes and sequence types (STs) was identified, including twelve previously unreported STs. Biotype 1A, exhibiting greater genetic diversity than more pathogenic biotypes (3 and 4), was frequently found in human clinical cases. Phylogenetic analysis revealed two main lineages, with isolates primarily clustered by biotype and pathogenic traits. Antimicrobial susceptibility testing revealed 46.7% (49/105) of isolates were multidrug resistant (MDR), with frequent resistance to polymyxin B (100%), azithromycin (50.5%), and sulfanilamide isoxazole (31.4%). These findings highlight the ecological complexity and diversity of Y. enterocolitica, especially non-pathogenic biotype 1A strains, and underscore the need for enhanced food safety and antimicrobial stewardship to mitigate the public health impact of Y. enterocolitica infections. KEY POINTS: Biotype 1 A strains exhibited greater genetic diversity than pathogenic biotypes. Pathogenic strains were mainly associated with lineage HC1490_2, not HC1490_10. Higher MDR levels were observed in biotype 3 and 4 strains.