Antimicrobial resistance profiling of coagulase negative staphylococci isolated from bovine mastitis

Abstract

Mastitis plays a crucial role in the economics of dairy industry by deteriorating the quality and quantity of milk produced, as well as endangering the animal health and welfare. The objective of this study was to investigate the antimicrobial resistance (AMR) profile of coagulase negative staphylococci (CNS) isolated from bovine mastitis. Microbiological evaluation by morphological, cultural and biochemical characterisation as well as by monoplex polymerase chain reaction (PCR) of the 83 quarter milk samples revealed that CNS were the most predominant bacteria (32.53%). It was also concluded that most of the CNS were resistant to multiple antibiotics. The phenotypic and genotypic AMR profiling was done using in vitro disc diffusion assay and PCR, respectively, to identify the resistance pattern towards penicillin, methicillin, tetracycline and enrofloxacin. The results depicted a significant difference between the phenotypic and genotypic resistance of CNS against penicillin, methicillin and tetracycline. This outcome on the interaction of phenotypic and genotypic AMR profiling is intriguing and opens a huge scope for future studies on the transcriptomic and proteomic aspects of drug resistance. A better knowledge of the AMR profile guides the dairy producers in developing suitable timely intervention strategies for the economic management of mastitis, which in turn helps in tackling AMR and reduces the threat of its zoonotic transmission.