C2-1832. Molecular Epidemiology and Antimicrobial Resistance Mechanisms of Methicillin-Resistant Staphylococcus aureus Isolated from Bovine Milk
Session: Slide Session: MRSA and Other Resistant Bacteria in Animals and Man
Monday, October 27, 2008: 12:00 AM
Room: Room 151B
Background: The aim of this study was to identify methicillin resistant Staphylococcus aureus (MRSA) strains in our collection of S. aureus gathered from 2002 to 2006 from milk samples in Aydin region in Turkey. Methods: A total of 93 S. aureus strains isolated from bovine milk with mastitis were tested for methicillin resistance and 16 were resistant to methicillin. MRSA strains were studied further for their staphylococcal cassette chromosome mec (SCCmec) types, antimicrobial susceptibilities, mechanisms of resistance and presence of Panton-Valentine leukocidin (PVL) toxin gene. Results: The MRSA strains were multi-drug resistant. The susceptibility rates to antimicrobials tested were 0%, 0%, 0%, 0%, 6.25%, 16.25%, and 56.25% for erythromycin, clindamycin, chloramphenicol, gentamicin, tetracyclin, ciprofloxacin, and vancomycin, respectively. All tetracycline and gentamicin resistant strains carried tet(M) and aac(6)-aph(2) gene respectively. Among macrolide resistant isolates 9 had erm(A), and 7 had both erm(A) and erm(B) genes. The molecular characterization by pulsed-field gel electrophoresis (PFGE) showed presence of 2 clones with their variants. The type B clones were type IV with SCCmec typing and strains with pulsed type A were SCCmec III. None of the isolates harboured the PVL gene. Conclusions: Presence of hospital related MRSA clones indicates transmission of these strains between human and animals. In case of clonal spread beside the infected animals treatment of MRSA carrier farm workers should also be considered. Hygienic measures and rational antibiotic use may avoid resistance selection, clonal dissemination of resistant strains and decrease economic loose due to mastitis in dairy herds.
Bulent Bozdogan, Adnan Menderes Universitesi Hastanesi, Aydin, Turkey, Serten Tekbiyik, Adnan Menderes Universitesi Veteriner Fakultesi, Suheyla Turkyilmaz, Adnan Menderes Universitesi Veteriner Fakultesi, Aydin, Turkey and  S. Turkyilmaz, None.