Methicillin-Resistant Staphylococcus Aureus Causing Bovine Mastitis in Egypt

Increasing the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in bovine milk, characterized by multidrug resistance (MDR) and the presence of resistance genes, poses significant challenges for mastitis treatment and raises public health concerns. This study investigated the antimicrobial resistance profiles of S. aureus isolates from clinical and subclinical mastitis cases in Egyptian dairy cattle. A total of 480 milk samples (120 cows, one sample per udder quarter) were analyzed. Mastitis was detected in 32.5% (156/480) of samples, with 27 S. aureus isolates recovered. All isolates harbored the mecA gene and exhibited resistance to 8–10 antibiotics, with multiple antibiotic resistance (MAR) indices ranging from 0.61 to 0.82. Resistance to erythromycin, oxacillin, and methicillin was universal (100%), while ceftaroline showed the lowest resistance rate at 11.1%. These findings highlight the high risk of MRSA contamination in milk, emphasizing the need for stringent hygiene measures and antimicrobial resistance monitoring in dairy production systems