MRSA in Dairy Cattle: A Review

Abstract

Mastitis is a global problem as it adversely affects animal health, affecting quality and the economies of milk production. In the last three decades, world milk production has increased by 50%, from 482 million tons (MT) to 754 million tons in 2012. Apart from mastitis, the chronic shortage of feed coupled with poor quality of fodder is widely regarded as the major constraint in dairy productivity at the production level. Mastitis can occur as per-acute, acute and chronic form which warrants use of antibiotics parenterally as well as locally. Staphylococcus aureus is perhaps the pathogen of greatest concern because of its intrinsic virulence, its ability to cause a diverse array of infection. MRSA has emerged as a public health/antimicrobial resistance problem both in human and veterinary medicine. More than 90% of Staphylococcal isolates now produce penicillinase. Resistance to penicillin mainly occurs by spread of resistant strains of MRSA whose clones rapidly spread, often becoming the resident clones and accounting for an increasing percentage of nosocomial infections. Several novel resistance genes have been discovered in MRSA ST398. Due to their characteristic multi-host specificity, ST398 strains can represent an efficient vehicle of the multidrug-resistant determinants that are plasmid-encoded, favoring their transmission and spread.