Molecular characterization and antimicrobial resistance of

Yersinia enterocolitica is a well-known foodborne pathogen that is widely distributed among domestic and wild animals. This study aimed to determine the prevalence of Y. enterocolitica in raw chicken meat and to characterize the isolates in terms of bio/serotypes, virulence factors, antimicrobial sensitivity, and genetic diversity. In 2021-2023, a total of 622 raw chicken meat samples were collected, from which Y. enterocolitica strains were isolated and confirmed by 16S rRNA detection. Biotype and serotype were identified using biochemical assays and agglutination methods, respectively. Six virulence-associated genes were examined using polymerase chain reaction (PCR). Antimicrobial susceptibility was assessed via the disk diffusion, and molecular typing was conducted by PCR ribotyping. The overall prevalence of Y. enterocolitica was 9.3%. A significant relationship was found between seasonal variation and prevalence (p=0.0001). Bio/serotypes 1A/O:8, 1A/O:5, 1A/O:NI, 1B/O:8, and 1B/O:NI were identified, with most isolates belonging to 1A/O:NI and 1A/O:8. A significant relationship was also observed between seasons and biotype distribution (p=0.031). In biotype 1B, the most frequent virulence genes were ystA, myfA, virF, ail, and inv, whereas biotype 1A predominantly harbored ystB and inv. All isolates were susceptible to 14 antibiotics. Ceftazidime and ampicillin resistance, however, was 100%. Notably, there were also notable levels of resistance to trimethoprim-sulfamethoxazole and nitrofurantoin. Pathogenic strains (IRT1 and IRT2) were grouped independently from non-pathogenic strains (IRT3) using PCR ribotyping. The detection of highly pathogenic Y. enterocolitica (1B/O:8) in Iran may pose a serious public health concern.