Antibiotic Resistance Profile of Methicillin-Resistant Staphylococcus aureus in Abeokuta, Nigeria

A considerable increase in infections caused by methicillin-resistant Staphylococcus aureus (MRSA) has caused a high rate of morbidity among the populace with huge economic loss and severe debility. Therefore, this study examines the pattern of antibiotic resistance of MRSA in clinical samples of patients in Abeokuta, Nigeria using standard recommended procedures. Coagulase test, β-lactamase production, and mannitol fermentation were performed using standard methods. Antibiotic susceptibility was determined using disc diffusion assay and minimum inhibitory concentration by micro-broth dilution method. Vancomycin and Azithromycin resistance profile was performed using colorimetric micro-broth dilution assay. Multi-resistant antibiotic index of MRSA was also determined.

A total of 338 clinical specimens of Pus, Aspirate, Ear, and Wound swabs were collected from three major health facilities in Abeokuta, Nigeria. Each sample was cultured for bacteria isolates and examined for colonial and cellular morphology while biochemical characterization was performed. Of the 161 Staphylococcus aureus (32.2%) isolated; there was no significant disparity found in relation to the study sites (c2=7.145, p-value = 0.308). 60.2% of the S. aureus analyzed were beta-lactamase producers while only 39.8% were β-lactamase negative. More than 65% of MRSA showed resistance to Cotrimoxazole, Tetracycline, Cefoxitin, and Erythromycin while 96.9% and 98.5% were resistant to Vancomycin and Azithromycin at MIC>16ug/mL respectively. All the MRSA showed MBC>64ug/ml to both Vancomycin and Azithromycin. Multi-antibiotic resistance index rate of more than 0.2 was shown by 97.0% MRSA to 12 different antibiotics.

The present study indicates a high prevalence rate of MRSA that require empirical and urgent intervention to prevent staphylococcal infection among the hospital patients and its outbreak.