Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 7 3 2015 11 25 161 167 EN Seyed Asghar Havaei Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Behnaz Assadbeigi Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Bahram Nasr Esfahani Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Nafiseh Sadat Hoseini Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Nahid Rezaei Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Seyed Rouhollah Havaei Postgraduate student of endodontics, Department of endodontics, School of dentistry, Zahedan University ofMedical Sciences, Zahedan, Iran . 2015 11 24 Background and Objectives:  Staphylococcus aureus is one of the main causatives of bovine mastitis. Resistance of some strains to methicillin, can complicate the treatment of its infections. On the other hand, enterotoxin production is also im- portant. Therefore, the aim of our study was to investigate the methicillin resistance and enterotoxin production in S. aureus isolates caused bovine mastitis. Materials and Methods: Four hundred and fifty milk samples were collected. After isolation of Staphylococcus aureus, MRSA strains were detected by cefoxitin disc diffusion and oxacillin agar screening methods. DNA was extracted by phenol – chloroform method and PCR was applied for mecA, sea and seb genes. SCCmec types of mecA gene were identified using multiplex-PCR. Results: Fifty-four (12%) S. aureus were isolated. Out of these, 10 and 9 MRSA strains identified by cefoxitin disc diffusion and oxacillin agar screening methods, respectively. All 10 MRSA isolates identified by cefoxitin disc diffusion, were positive for mecA gene and all of them belonged to SCCmec type IV. The sea genes were detected in 19 isolates and only two isolates were positive for seb genes. One isolate possessed both sea and  seb genes. Conclusion: Findings of this study indicated that results of cefoxitin disc diffusion test is in concordance with the PCR for mecA gene and has a higher sensitivity compared to oxacillin agar screening method. Finally, Our findings suggest that enterotoxin A is the dominant type. https://ijm.tums.ac.ir/index.php/ijm/article/view/818 https://ijm.tums.ac.ir/index.php/ijm/article/download/818/502