A study on Methicillin resistant Staphylococcus aureus mastitis in dairy cows

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious problem in dairy animals suffering from mastitis. The study was carried out to evaluate the incidence of Methicillin resistant S. aureus from clinical mastitis milk samples and their antibiotic resistance profile and characterised with respect to the molecular features that contributed to the resistance in these pathogens. Isolation and identification of Methicillin resistant S. aureus were performed from acute clinical mastitis samples. The isolates were tested using agar disc diffusion method for their antimicrobial susceptibility and modified resazurin assay micro dilution technique for MIC to 8 different antimicrobial drugs. A total of 235 clinical mastitis milk samples from dairy cows were cultured for incidence of S. aureus. Methicillin resistant S. aureus was isolated from a total of 12 (44.25%) of the 116 S. aureus samples. Based on the antimicrobial sensitivity and MIC results, MRSA isolates were found sensitive to gentamicin, enrofloxcain, amoxicillin+sulbactam, ceftriaxone and resistant to amoxicillin, oxytetracycline, penicillin G and oxacillin. Most of MRSA isolates were found to be multi-drug resistant. MRSA alert kit test and mecA and blaZ target gene PCR were found to be useful in the confirmation of MRSA.