Buffalo represent a major source of milk in Pakistan. However, production is impacted by the disease bovine mastitis. Mastitis causes significant economic losses, with Staphylococcus aureus (S. aureus) being one of its major causative agents. While much work has been done understanding the epidemiology of bovine mastitis in Pakistan, detailed molecular characterization of the associated S. aureus is unavailable. In the current study both the epidemiological and molecular characterization of S. aureus from bovine mastitis in the Hazara division of Pakistan are examined. S. aureus was isolated from 18.41% of the animals, and left quarters more prone to infection (69.6%) than right quarters (30.4%). Sub-clinical mastitis (75.31%) was more prevalent than clinical mastitis (24.69%), with infections evenly distributed amongst the eight districts. Molecular characterization revealed that only 19.6% of the isolates were methicillin-resistant, and four strains types identified, including ST9-t7867-MSSA, ST9-MSSA, ST101-t2078-MSSA, and ST22-t8934-MRSA-IVa. Antiseptic resistance genes were not detected in the isolates, and low levels of antibiotic resistance were also noted, however the methicillin-resistant strains had higher overall antibiotic resistance. This study represents the most complete molecular typing data for S. aureus causing bovine mastitis in the Hazara district of Pakistan, and the country as a whole.

Staphylococcus aureus is one of the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens among which multidrug resistance has emerged. Resistance to methicillin has resulted in clinicians using the antibiotic of last resort, vancomycin, to treat infections caused by methicillin-resistant S. aureus (MRSA). However, excessive use and misuse of vancomycin are major causes of resistance among S. aureus strains. South Asia encompasses ~25% of the world’s population, and countries in South Asia are often characterized as low- and middle-income with poor healthcare infrastructure that may contribute to the emergence of antibiotic resistance. Here, we briefly highlight the mechanism of vancomycin resistance, its emergence in S. aureus, and the molecular epidemiology of non-susceptible S. aureus to vancomycin in the South Asian region.