Antimicrobial Susceptibility and Resistance Patterns of Staphylococcus aureus Isolated from Mastitic Cows in Hawassa City and Its Suburbs, South Ethiopia

Staphylococcus aureus is the primary cause of mastitis in dairy cattle globally and frequently exhibits multidrug resistance due to excessive antibiotic use on farms. This study aimed to isolate S. aureus from mastitis affected cows and evaluate its antimicrobial susceptibility. A total of 172 milk samples from confirmed mastitic cows were cultured using standard bacteriological methods. Forty-four S. aureus isolates were tested against 11 common antimicrobials using the Kirby–Bauer disk diffusion method. S. aureus was isolated from 51.2% of samples, with significant resistance observed against ampicillin (84.1%), penicillin (81.8%), tetracycline (36.4%), and amoxicillin-clavulanic acid (34.1%). MDR was noted in 43.2% of isolates. In contrast, S. aureus demonstrated complete susceptibility to ceftriaxone and gentamicin (100%), and high susceptibility to streptomycin (88.6%), erythromycin (88.6%), nitrofurantoin (72.7%), and cefotaxime (72.7%). The significant isolation rate of S. aureus and its MDR underscore the urgent need for enhanced veterinary practices and public health strategies. A comprehensive approach that includes improved management, ongoing education for veterinarians and dairy farmers, responsible antimicrobial usage, and regular monitoring of resistance is essential to tackle the escalating threat of antimicrobial resistance in bovine mastitis.