Methicillin-resistant Staphylococcus aureus (MRSA) isolated from raw milk and nasal swabs of small ruminants in Abeokuta, Nigeria.

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA), an important widespread cause of severe infection in both humans and animals, is a significant pathogen of public health concern. This study examined the presence of MRSA in 400 samples comprising 200 raw milks (145 from goat and 55 from sheep) and 200 nasal swabs (145 from goats and 55 from sheep) collected from ten different locations in Abeokuta, Nigeria. Samples were examined using standard bacteriological methods for the isolation and identification of Staphylococcus aureus and culture on oxacillin (6μg/ml) and cefoxitin (2μg/ml) selective media for the detection of MRSA. Suspected MRSA isolates were confirmed by latex agglutination test for the detection of penicillin-binding protein 2a (PBP2a). Antibiotic susceptibility testing was determined by Kirby Bauer disc diffusion method. Staphylococcus aureus was detected in 72 (18%) of 400 samples of which 52 (13%) were confirmed as MRSA. Methicillin-resistant S. aureus was detected in raw milk (37 of 200; 18.5%) and nasal swab (15 of 200; 7.5%). There was no significance difference (p > 0.05) in the prevalence of MRSA in sheep (37.7%) and goat (23.4%). The MRSA isolates showed resistance to ampicillin (100%), cloxacillin (100%), sulphamethoxazole-trimethoprim (100%), amoxicillin-clavulanate (84.6%), ceftriaxone (75%), cefuroxime (69.2%), erythromycin (65.4%), streptomycin (38.5%), ciprofloxacin (23.1%), pefloxacin (21.2%) and gentamicin (17.3%). The presence of multidrug-resistant MRSA in small ruminants reared in Abeokuta metropolis may be due to regular use of antibiotics and unhygienic practices by farmers. This in turn constitutes a potential public health risk to the owners, consumers of small ruminant products and the general populace.