Prevalence of Yersinia Species in Traditional and Commercial Dairy Products in Isfahan Province, Iran

Background: Yersinia species, especially Yersinia enterocolitica, are considered as the most prevalent milk-borne pathogens. Several serological and molecular techniques have been developed for rapid and safe diagnosis of yersiniosis. Objectives: This study was carried out to assess the prevalence rate of Yersinia species, especially Y. enterocolitica, in milk and dairy products in Isfahan province, Iran. Materials and Methods: A total of 285 commercial and traditional dairy products as well as 267 pasteurized and raw milk samples were collected during one year. The samples were studied by culturing and the positive-culture samples were investigated using PCR techniques. Results: The results of culture showed that 52 (9.42%) and 28 (5.07%) of the total 552 milk and dairy samples were positive for presences of Yersinia species and Y. enterocolitica, respectively. Totally, 24 of 28 Y. enterocolitica isolates by culture were positive in PCR test (4.59%). Raw cow milk and traditional cheese had the highest prevalence of Yersinia species and Y. enterocolitica, respectively. There were no positive results for pasteurized cow milk, raw camel milk, commercial ice cream, commercial cheese, yoghurt, Doogh, butter and curd. Yersinia species and Y. enterocolitica had the highest prevalence in autumn (15.15% and 10.6%, respectively). Significant differences regarding P < 0.05 were observed between the presences of Yersinia species and Y. enterocolitica in various samples and seasons. Conclusions: Sanitation and pasteurization are the best ways to increase the microbial quality and particularly decrease the load of Yersinia species. The ability of Yersinia species to growth in Doogh, yoghurt, curd and butter is very low.