Molecular Investigation of Clinical Isolates of Staphylococcus aureus from Cases of Boil Infection

Abstract

Background: Boil, a pyodermal infection caused by Staphylococcus aureus is a very common skin disease. It is characterized by pus filled lump at specific anatomical loci. Objectives: This study evaluated the antimicrobial a c t i v i t y o f v a n c o m y c i n p o w d e r i n v a r i e d concentrations alongside with 30μg vancomycin standard discs, determined the minimum inhibitory concentration and plasmid profiles of the resistant isolates of Staphylococcus aureus from boil infection. Methods: A total of one hundred (100) exudates from boils were collected with a sterile swab for bacteriological examination; the samples were culture on mannitol salt agar, followed by Gram staining and other conventional biochemical characterization. The isolates were tested by agar diffusion method against varied concentrations of vancomycin and a standard 30 μg vancomycin disc as a control. The resistant isolates from standard vancomycin disc were subjected to molecular investigation to determine the source of their vancomycin resistance. Results: Remarkable zones of growth inhibitions to varied concentrations of vancomycin powder that ranged from 32μg/mL-1.0 μg/mL were recorded, a l t h o u g h , v a n c o m y c i n a n t i b i o t i c s a r e n o t concentration dependent. The minimum inhibitory concentration for the 60 isolates examined elicited varied values. Of the 60 isolates exposed to plasmid investigation, fourteen(14) elicited resistance that were plasmid mediated which molecular weight ranged from 0.82 kb - 27.22kb. Conclusion: The resistance of the isolates observed from plasmid patterns with varied molecular weights could aid the transferability of that factor to other related bacteria which could be a threat to therapeutic management of boil infection.