AMR profile of methicillin-resistant s. Aureus (mrsa) and methicillin-sensitive s. Aureus (mssa) isolated from milk samples

Abstract

The present study was conducted to determine the antimicrobial resistance profile of methicillin-resistant S. aureus and methicillin-sensitive S. aureus in milk samples. Quarter foremilk samples were collected from organized dairy herds and confirmed S. aureus isolates were subjected to antimicrobial sensitivity testing (AST) by disk diffusion method.  Out of total 194 Staphylococci spp. isolated from milk, 103 were confirmed as S. aureus by PCR amplification of nuc gene. The overall prevalence of S. aureus was 53.1 % (103/194). 61 (59.22 %) S. aureus isolates were phenotypically identified as MRSA and 42 (40.77 %) were MSSA. In MRSA and MSSA, highest resistance was observed for penicillin and lowest was observed for co-trimoxazole, enrofloxacin, gentamicin and tetracycline. Higher level of resistance was observed in MRSA than MSSA. Among MRSA, antibiotic resistance gene of highest prevalence was blaZ (39.34 %), followed by aacA-aphD (29.51 %), tetK (22.95 %), tetM (9.83 %) and ermA (6.55%). Similar prevalence of antibiotic resistance genes was found in MSSA. VanA gene was not found in our study.