Occurrence molecular characterization of Multidrug Resistant and methicillin resistant Staphylococcus aureus isolate from Bovine, Caprine milk and their handlers

Staphylococcus aureus is a zoonotic pathogen of public health significance commonly associated with bovine and caprine mastitis. Its ability to acquire antibiotic resistance, particularly methicillin resistance is mediated by the mecA gene that complicates treatment and further transmission by direct contact or through contaminated dairy products. This study was conducted to isolate S. aureus in the Jammu district and to assess their methicillin resistance and antibiotic susceptibility profiles. A total of 240 samples were collected, including raw milk (90), mastitis milk (90), teat skin swabs (30), and handler hand swabs (30). Staphylococcus aureus isolates were initially identified using standard bacteriological techniques, with molecular confirmation achieved through PCR amplification of the nuc and mecA genes. Out of 240 samples, 142 (59.16%) were positive for S. aureus. Among these, 90 isolates (63.38%) carried the nuc gene, confirming their identity as S. aureus, while 35 isolates (38.88%) were positive for the mecA gene, indicating methicillin resistance. Antimicrobial susceptibility testing was performed using the disc diffusion method against 15 commonly used antibiotics. High levels of resistance were observed against methicillin (71.14%), novobiocin (74.28%), and nalidixic acid (80%), whereas higher sensitivity was noted for bacitracin (85.71%), ciprofloxacin (77.14%), and gentamicin (77.14%). The presence of multidrug resistant and mecA-positive S. aureus isolates in milk, animals, and handlers underlines the potential public health risks associated with their transmission. The findings emphasize the need for improved hygiene practices on dairy farms, judicial use of antibiotics and continuous surveillance and monitoring of organised and unorganised sectors to mitigate the spread of MRSA in the food production chain.