title: Characterization of Staphylococcus aureus strains isolated from raw milk of bovine subclinical mastitis in Tehran and Mashhad.
abstract: Staphylococcus aureus is considered one of the most important food borne pathogens. A total of 111 isolates of S. aureus were cultured from raw milk samples during January 2009 to June 2009 from Tehran and Mashhad. The coagulase gene polymorphism and the prevalence of classical enterotoxin genes of S. aureus strains were determined by PCR-RFLP (restriction fragment length polymorphism) and Multiplex-PCR. Disk diffusion method was used to determine the susceptibility of isolates to antimicrobial agents as instructed by Clinical and Laboratory Standards Institute. Sixty-seven % of the isolates harboured one or more enterotoxin genes. The most prevalent gene was sec, found in 59 % of the isolates. Approximately 8% of the isolates were positive for sea, seb and sed genes. Only one isolate had see gene. The rate of coexistence of enterotoxin genes was 14%. All S. aureus isolates were susceptible to ciprofloxacin, gentamicin, imipenem, minocycline, oxacillin and vancomycin. They were resistant to ampicillin (64%), penicillin (56%), clindamycin (22%), tetracycline (22%), doxycycline (19%), teicoplanin (13%), rifampin (2%) and trimethoprim-sulfamethoxazole (2%). On the basis of coagulase gene analysis of 111 S. aureus isolates, the PCR products of 56 isolates were digested with Alu I that produced three distinct patterns. These data indicate the high prevalence of enterotoxigenic S. aureus in raw bovine milk in Tehran and Mashhad, and highlight the importance of proper quality control of dairy products for public health.
authors.affiliation: Research Centers for Gastroenterology and Liver Diseases, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Navid
authors.initials: N
authors.lastname: Sahebekhtiari
authors.forename: Zahra
authors.initials: Z
authors.lastname: Nochi
authors.forename: Mohammad Amin
authors.initials: MA
authors.lastname: Eslampour
authors.forename: Hossein
authors.initials: H
authors.lastname: Dabiri
authors.forename: Mehdi
authors.initials: M
authors.lastname: Bolfion
authors.forename: Morovat
authors.initials: M
authors.lastname: Taherikalani
authors.forename: Babak
authors.initials: B
authors.lastname: Khoramian
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zali
authors.forename: Mohammad
authors.initials: M
authors.lastname: Emaneini
mesh_terms: D000818:Animals; D002417:Cattle; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*