Isolation and Characterization of in Bovine Milk from Rewa, India.

Mastitis in dairy animals affect milk quality and quantity, animal health and welfare, antimicrobial use and economics of dairy farm, and antimicrobial residues in milk. is most common mastitis pathogen with ability to cause infections which are difficult to treat. The present study aimed to characterize the strains associated with dairy animal with reference to its virulence, biofilm formation, antimicrobial resistance including methicillin and penicillin G resistance. A total of 100 bovine milk samples were screened by bacterial culture method, out of which 18 and 6 methicillin-resistant (MRSA) isolates were identified and characterized for virulence determinants. The strains were uniformly positive for the virulence determinants. However, the hemolysis in blood agar was found to be specific but not a sensitive criterion for virulence. The biofilm formation ability of the isolates showed 61.66% of and 83.33% of MRSA strains were positive by Microtiter plate method. The biofilm formation genes (A and D) were detected in all the strains. The multi-drug resistance profile of the strains was studied by disk diffusion assay where over 70% of strains were sensitive to all the anti-microbial agents (except penicillin) and only 33.33% of the strains had the MAR index above 0.2. All the MRSA strains (100%) had a MAR index of ≥ 0.2. All the strains showed resistance to penicillin which is considered as a prognostic marker for mastitis. The presence of penicillin and/or methicillin resistant, biofilm forming mastitis strains can severely affect the treatment outcomes and economics of small dairy farmers of the region. Further studies to understand the population structure of the strains, by whole genome or traditional sequence-based methods and MIC values of antibiotics are required.