Epidemiological identification and molecular detection of antimicrobial resistant staphylococcus species in bovine mastitis

Abstract

Mastitis is a consistent problem in the dairy industry and causes huge economic losses due to loss of milk production and milk quality. The study was carried out to assess the prevalence of mastitis pathogens and their antimicrobial resistance genes. A total of 155 milk samples were collected and cultured, of which 25 samples were positive for Staphylococcus spp with a rate of 20.16%. The bacterial species were confirmed by PCR. Among Staphylococcus spp, the coagulase negative staphylococci (16.13%) were predominantly identified than Staphylococcus aureus (4.03%). In coagulase negative staphylococci, Staphylococcus chromogenes was predominantly detected, followed by Staphylococcus sciuri and Staphylococcus xylosus. The antibiogram showed that Staphylococcus spp were 90% sensitive to ceftriaxone, ampicillin-sulbactam, ampicillin and 100% resistant to methicillin, and also 40% resistant to enrofloxacin, oxytetracycline and co-trimoxazole. Out of 25 Staphylococcus isolates, 11 isolates had the AMR genes like mecA, blaCTXM-G1, aac (6’)-aph(2, tetM gene and gyrA with prevalence rates of 24, 8, 12, 8 and 32%, respectively, of which 36.36% of isolates were multidrug resistant. The Staphylococcus spp predominantly harboured gyrA gene, followed by mecA. The study exclusively documented the fluoroquinolone resistant staphylococci in bovine mastitis.