Detection of Classic Enterotoxin Genes and Coagulase Gene Typing of Staphylococcus Aureus Isolated from Raw Cow Milk in Isfahan

Background and Aims: Staphylococcus aureus (S. aureus) is considered as one of the most dangerous pathogenic bacteria due to the production of extracellular toxins. The objective of this study was to determine the prevalence of S. aureus and to characterize the recovered strains for their enterotoxin-producing genes in raw cow milk. Materials and Methods: During 9 months duration of the study, a total of 322 raw milk samples were collected from different markets in Isfahan province in Iran. S. aureus isolates were identified by bacteriology and biochemical tests. The isolates were typed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for detection of coa gene and genes encoding classic enterotoxins (sea, seb, sec and sed). Results: A total of 109 strains were positive for at least one type of staphylococcal enterotoxin genes with sea being the predominant. The isolates were grouped into 3 genotypes I, VIII and IX using RFLP analysis results of the genes. Conclusions: The alarmingly high prevalence of S. aureus and their enterotoxin genes in raw cow milk should raise awareness about the food safety of such milk and milk products.