Isolation, identification and antibiogram of coagulase negative staphylococci from bovine clinical mastitis

The aim of this study was to identify the primary bacteria associated with clinical mastitis in dairy cows and to assess the antimicrobial resistance pattern of the commonest isolate using phenotypic methods. The milk samples were collected from 83 domesticated dairy cows suffering from clinical mastitis (CM), from an organised dairy farm as well as cows presented with CM at the University Veterinary Hospital (UVH), Mannuthy, Thrissur, Kerala. Microbiological analysis, using morphological, cultural and biochemical properties as well as molecular identification using polymerase chain reaction (PCR) revealed that coagulase-negative staphylococci (CNS) were the most predominant (40.31 per cent) bacteria, followed by Staphylococcus aureus (32.83 per cent), Micrococci spp. (11.94 per cent), Klebsiella spp. (7.46 per cent) Escherichia coli (4.48 per cent) and Streptococci (2.98 per cent). The majority of the bacteria were resistant to more than one class of antimicrobials (aminoglycosides, β lactams, fluoroquinolones or tetracyclines). Furthermore, our findings revealed that the CNS is highly resistant to β-lactam family of antibiotics and that CNS may play a significant role in clinical mastitis of dairy cows.

Keywords: Antibiogram, coagulase negative staphylococci, mastitis