Identification and characterization of the virulence genes in Yersinia enterocolitica strains isolated from sheep and goat milk in Shahrekord

Yersinia enterocolitica is a Gram-negative intestinal pathogen that is transmitted to humans through water and food. Milk is one of the main sources of the infection transmission to humans and its contamination with bacteria such as Y. enterocolitica can cause serious damages. The present study aimed to isolate Y. enterocolitica and its virulence genes from small ruminant milk in Shahrekord, Iran using microbial culture and PCR method. In this cross-sectional descriptive study, 100 raw milk samples were collected randomly from different parts of Shahrekord, and cultured on a CIN agar medium. In order to detect Y. enterocolitica O:3 serotype and toinvestigate the presence of virulence genes, positive- culture samples were further assessed by PCR method using specific primers. According to the results, 9% of total sheep and goat milk samples were positive after microbial culture. Notably, all positive samples were sheep milk samples. Five percent of the positive samples were confirmed as O:3-positive serotypes using PCR method. The ail gene was found in four isolates, the yadA gene was reported in three isolates, and the virF and ystA genes were identified in two isolates. Isolation of Y. enterocolitica from raw milk was indicated high risks of yersiniosis associated with raw sheep milk. Based on our results, sheep's milk can be considered as a potential cause of human infection to Y. enterocolitica.