Antimicrobial Resistance of Staphylococcus Aureus in The Dairy Industry: A One Health Concern

The global dairy industry faces a persistent and escalating challenge from Staphylococcus aureus, a primary agent of bovine mastitis and a major public health pathogen. This review synthesizes evidence to examine the complex epidemiology of antimicrobial resistance (AMR) in dairy-associated S. aureus, a crisis propelled by antimicrobial misuse in livestock and facilitated by dynamic transmission at the human-animal-environment interface. Studies from Africa, Asia, Europe, and America reveal a high and geographically variable prevalence of multidrug-resistant (MDR) and methicillin-resistant S. aureus (MRSA) strains, with particularly concerning resistance to beta-lactams and tetracyclines. Molecular analyses highlight the adaptation of successful clonal complexes (e.g., CC97, ST-1) in dairy herds and the widespread carriage of enterotoxin genes, resulting in zoonotic and food safety risks independent of AMR status. The transmission of resistant strains is amplified by suboptimal farm hygiene, direct occupational contact, and environmental contamination, with raw milk serving as a key vehicle for human exposure. The convergence of MDR, methicillin resistance, and potent virulence determinants in these strains poses a severe One Health threat, leading to difficult-to-treat infections that increase morbidity and healthcare costs. Mitigating this crisis requires an integrated, multi-pronged strategy. This includes stringent antimicrobial stewardship such as culture-guided therapy and selective dry cow treatment coupled with improved biosecurity, milking hygiene, and comprehensive surveillance. The development and adoption of alternative interventions, including vaccines, bacteriophages, and probiotics, are promising avenues to reduce antibiotic dependence. Concerted, cross-sectoral action under a One Health framework is urgently needed to curb the spread of AMR, protect animal welfare, ensure dairy sector sustainability, and safeguard global public health security.