Background Bovine mastitis is an important disease that cause to major economic losses in dairy herds. Mastitis is caused by a wide spectrum of pathogens and, epidemiologically categorized in to contagious and environmental mastitis. Staphylococcus aureus is one of the most common etiological agents of contagious bovine mastitis worldwide. The aim of this study was to phenotypically and genetically detection of S. aureus isolates recovered from bovine milk samples from industrial dairies in Hamedan, Iran. Methods In present study a total of 120 milk samples taken from June, 2016 to May, 2017. S. aureus isolation and conformation was done based on conventional microbiological tests and presence of femA gene, respectively. Disc diffusion test was used to test the susceptibility of S. aureus isolates according to the guidelines of Clinical Laboratory Standards Institute (CLSI). Results A total of 42 S. aureus isolates from milk samples were identified and subsequently confirmed. Our results revealed that penicillin was the less effective antibiotic. However, none of the isolates was resistant to vancomycin. The results of antibiotic sensitivity test showed that 2 (4.76%) isolates were phenotypically resistant to oxacillin and therefore categorized in Methicillin-resistant Staphylococcus aureus (MRSA) group. Conclusion According to high prevalence rate of this pathogen among bovine farm of Hamedan region, we suggest that approved hygiene programs must be established for control of S. aureus speeding. Keywords: Bovine mastitis, Staphylococcus aureus, Hamedan
