Antimicrobial susceptibility pattern and SCCmec types of methicillin-resistant coagulase-negative staphylococci from subclinical bovine mastitis in Hatay, Turkey

Eighty-nine isolates of coagulase-negative staphylococci (CoNS) of eight species from subclinical bovine mastitis were screened for the phenotypic and genotypic methicilline-resistance. In addition, all methicillin-resistant (MR) isolates indicating the mecA gene were examined by PCR for the antimicrobial susceptibility patterns, and staphylococcal cassette chromosome mec (SCCmec) types were also determined by multiplex PCR. A total of 21 (23.6%) CoNS isolates were found to be resistant to oxacillin in broth microdilution assay. All isolates phenotypically resistant to oxacillin did not have the mecA gene, which was only found in 14.6% (13) of the isolates. Most MR-CoNS isolates were highly resistant to erythromycin (92.3%), fusidic acid (84.6%), penicillin (76.9%), and rifampycin (61.5%), and susceptible to mupirocin (100%), tetracycline (100%), vancomycin (100%), clindamycin (92.3%), and sulfamethoxazole-trimethoprim (69.2%). In conclusion, a high rate of antimicrobial resistance among MR-CoNS isolated from food producing animals emphasises the need for periodic surveillance of their resistance.