MRSA in Raw Milk: Isolation, Molecular Characterization, and Antibiotic Profiling

Abstract

A total of 100 milk samples were randomly collected from dairy cows before milking to investigate the presence of MRSA using selective medium (ORSAB) beside detection of some resistance genes by PCR and finally determine the antibiotic profile of the recovered isolates. It was found that the overall percentage of isolation of MRSA was 24% (24/100), (25.8%) 16/62 in milk samples of mastitic cows and (21.1%) 8/38 in raw milk samples of free cows. Molecular characterization of MRSA strains showed that 79.2% (19/24) were harbored mecA gene while none of them harbored mecC gene. In addition, MRSA isolates showed high resistance to cefoxitin (79.2) followed by Tetracycline (33.3%), Vancomycin (20.8%) and Linezolid (15.5%). Whereas the tested MRSA strains showed higher susceptibility to Linezolid (87.5%) followed by Vancomycin (79.2%) and Tetracycline (66.7%). According to the recorded results in the present study, it is concluded that cow’s milk played a significant role in transmission and dissemination of MRSA that may create the opportunity for the transmission of such bacteria to consumers.