Antimicrobial resistance pattern of Staphylococcus species in mastitis affected dairy cows
Author(s): T Ramasamy
Abstract: Antimicrobial resistance (AMR) is a global health concern impacting both human and veterinary medicine. Mastitis, a major production disease in dairy cattle, is often caused by Staphylococcus spp., which increasingly shows resistance to multiple drugs. This study investigated the prevalence and antimicrobial resistance of Staphylococcus spp. isolated from mastitis-affected dairy cows in Tamil Nadu, India. Forty milk samples from clinical and subclinical cases (August 2024–March 2025) were screened by California Mastitis Test, cultured on mannitol salt agar, and tested for antimicrobial susceptibility against 12 antibiotics using CLSI guidelines. Staphylococcus spp. was isolated in 18 samples (45%), with high resistance to methicillin (77.78%) and penicillin G (72.22%), alongside notable resistance to enrofloxacin and amikacin (61.11% each). Amoxicillin–clavulanate (66.67%) and tetracycline (55.56%) retained the highest sensitivity. The high multidrug resistance highlights therapeutic challenges and zoonotic risks, emphasizing the need for culture-based therapy, antimicrobial stewardship, and a One Health approach.
