PREVALENCE AND CHARACTERIZATION OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS IN DOMESTIC LIVESTOCK (LA-MRSA) OF DHARAN, NEPAL

Abstract

Staphylococcus aureus is a gram positive, non-motile, non-spore-forming bacterium. Pathogenic staphylococci are identified by their ability to produce coagulase, thus clot the blood. It is found as a commensal associated with skin, skin glands, and mucous membranes. The study aimed to determine prevalence and characterization of LA-MRSA isolated from domestic livestock of Dharan, Nepal. Overall, 320 samples were collected and transported to the microbiology lab in the cold chain. The skin of cattle was swabbed aseptically by a sterile cotton swab and transported to the laboratory in a cold chain. The samples were swabbed in Mannitol salt agar containing oxacillin powder of 6mg/L and incubated at 37°C for 24 hours. Staphylococcus aureus colonies were identified based on growth characteristics on MSA plates (golden yellow colonies), Gram’s stain and positive results for coagulase and catalase test. The purified isolates of MRSA were subjected to antibiotic susceptibility tests, Biofilm formation assays. MRSA was found to be prevalent in 10% of cattle. Antibiotic resistant pattern of the isolates were found to be sensitive to chloramphenicol 12 (37.5%) followed by ceftriaxone 12 (37.25%), gentamycin 9 (28.12%), cefotaxime 4 (12.5%) while MRSA was resistant to penicillin and vancomycin. The biofilm forming ability of isolated MRSA was performed by microtitre plate method. 5 (15.625) of 32 MRSA isolates were moderate biofilm forming MRSA., followed by 3 (9.375%) week biofilm formationa and 25 (75%) were non biofilm forming isolates. High prevalence of staphylococcal infections and the infection caused due to MRSA in humans as well as cattles shows the need of regular surveillance.