Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in dairy farms of Pokhara, Nepal.

Abstract

MRSA (Methicillin-resistant Staphylococcus aureus) are the strains of S. aureus that are resistant to all the β-lactam antibiotics. MRSA has received a lot of attention in recent years as a zoonotic organism when studies suggested the possibility of animals serving as reservoirs for human MRSA infection. A cross-sectional study was carried out from October, 2012 to January, 2013 to determine the prevalence of MRSA in dairy farms of Pokhara. Milk samples were collected from 10 dairy farms of Pokhara selecting 10 cattle from each farm thereby making a sample size of 100 cattle (400 quarters). Staphylococus aureus was isolated from milk samples using bacterial culture and biochemical tests. MRSA was identified using cefoxitin disk diffusion method. All the S. aureus isolates were subjected to antimicrobial susceptibility test. Out of 400 milk samples, S. aureus were isolated from 119 (29.7%) samples. MRSA were found in 45 (11.25%) milk samples. S. aureus isolates were found sensitive to ciprofloxacin (97.47%), gentamicin (94.95%), ceftriaxone (91.59%) and tetracycline (89.91%) in descending order while they were found least sensitive to cefoxitin (62.18%). Results clearly suggest the increasing resistance of S. aureus to β-lactam antibiotics causing emergence of MRSA.