Isolation and Evaluation Virulence Factors of Salmonella typhimurium and Salmonella enteritidis in Milk and Dairy Products

Nutritional and economic importance of milk and dairy products is undeniable. In a day, Millions of people use from these products in their daily deals but unfortunately the hygienic quality of milk and dairy products can be changed due to presence of microbial pathogens. Salmonella enteritidis and Salmonella typhimurium are two important milk-borne pathogens. Their pathogenicity is occurred by several putative virulence genes. This study was carried out for investigate the prevalence of Salmonella spp., Salmonella enteritidis and Salmonella typhimurium in milk and dairy products and study the presence of their virulence factors. Totally, 360 milk and dairy products were collected from Isfahan province and were immediately transferred to the Food Microbiology Research Center of Islamic Azad University of Shahrekord. All samples were cultured and their positive results were subjected to PCR method in order to determine the exact incidence rates of Salmonella spp., Salmonella enteritidis and Salmonella typhimurium and their virulence genes. Totally, 1.66% of samples were Salmonella positive. The incidence of Salmonella enteritidis and Salmonella typhimurium were 0.27% and 0.83%, respectively. Raw sheep milk had the highest prevalence of Salmonella spp. (7.5%). All of the Salmonella enteritidis and Salmonella typhimurium isolates harbored their certain virulence factors. To our best knowledge the present study is the first prevalence report of Salmonella spp., Salmonella enteritidis and Salmonella typhimurium in raw sheep and goat samples in Iran. Consumption of pasteurized milk and dairy products can reduce the risk of salmonellosis.