Pakistan’s dairy industry relies heavily on cows and buffaloes for milk production. The industry faces significant infectious disease challenges, including antibiotic-resistant bacterial infections that pose a serious threat to the health and productivity of dairy animals. Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of mastitis in dairy cows. In humans MRSA can cause from skin or soft-tissue infections to potentially fatal bloodstream infections. Twenty milk samples were collected from subclinical mastitic cows. Likewise, 20 skin swabs from milkmen were collected. The isolation attempts yielded 36 (20 of animal and 16 of human -origin) S. aureus isolates. Kirby-Bauer disc diffusion assay demonstrated significant antibiotic resistance in the S. aureus (80% animal and 75% human -derived) isolates. The isolated S. aureus were resistant to at least one of the following: Tylosin, Penicillin G, Trimethoprim, Sulfamethoxazole, Oxytetracycline, Gentamicin, and Norflaxacin. The mecA gene was detected in 28 (16 animal and 12 human -derived) isolates, suggesting widespread methicillin resistance. As an alternative to antibiotics, green synthesis of silver nanoparticles (AgNPs) using Azadirachta indica leaf extract was carried out. The synthesis of silver nanoparticles was optimized by adjusting reaction conditions and the particles were characterized using UV-Vis spectroscopy, FTIR, zeta potential analysis and TEM, confirming their stability and uniform size. The effectiveness of AgNPs against MRSA was evaluated by Time-kill and well diffusion assays. Time-kill assays revealed a dynamic inhibitory effect of biosynthesized AgNPs demonstrating strong antibacterial activity and the well diffusion assay indicated inhibition zones 20.38±6.19 mm. These findings highlight the potential of silver nanoparticles as an alternative to conventional antibiotics, offering a promising approach to combating MRSA in both dairy cows and humans.

To Cite This Article: Nasir S, Firyal S, Wasim M, Azeem S, Awan AR, Tayyab M and Saeed S, 2026. Methicillin-resistant Staphylococcus aureus, a one health challenge and Azadirachta indica silver nanoparticles, a possible solution. Pak Vet J, 46(6): 1586-1594. http://dx.doi.org/10.29261/pakvetj/2026.150