Antimicrobial Resistance Profile and Quinolone Resistance Genes in Staphylococcus aureus from Patients Attending Federal Medical Centre Keffi, Nigeria

Aims: This study investigated the antimicrobial resistance profile and quinolone resistance genes in Staphylococcus aureus from patients attending Federal Medical Centre, Keffi, Nigeria.

Methodology: A total of 240 clinical samples which comprised of high vaginal swabs, endocervical swabs, sputum, ear swabs, wound swabs, semen and eye swabs, were collected from the patients. Staphylococcus aureus was isolated and identified from these samples using standard microbiological method. Antimicrobial susceptibility testing of the isolates was performed and interpreted in accordance with the Clinical and Laboratory Standards Institute (CLSI) method. Ciprofloxacin-resistant S. aureus were screened for quinolone resistance genes using Polymerase Chain Reaction (PCR) method.

Results: Out of 240 clinical samples, the prevalence of S. aureus was 21.3%. The prevalence in relation to clinical samples was higher in eye swab (45.5%) and ear swab (44.4%), but lower in sputum (14.5%). The isolates were more resistant to oxacillin (88.2%), sulphamethoxazole/ trimethoprim (82.4%) and erythromycin (76.5%), but less resistant to ciprofloxacin (19.6%) and levofloxacin (5.9%). The most common resistance phenotypes in the isolates were sulfamethoxazole/trimethoprim (SXT) - clindamycin (DA) – ofloxacin (OX) - erythromycin (E) - rifampicin (RD) and SXT-DA-OX-E- streptomycin (S) -RD with an occurrence of (13.7%) each. The percentage occurrences of multidrug resistant and extensive-drug resistant isolates were 92.2% and 7.8% respectively. The occurrences of quinolone resistance genes in the ciprofloxacin-resistant isolates were: aac(6′)-Ib-cr (60.0%), gyrA and gyrB (50.0%), parC (40.0%), qnrB (20.0%) and qnrS (10.0%).

Conclusion: The isolates were less resistant to levofloxacin, cefoxitin, ciprofloxacin and gentamicin in the study location. Most of the ciprofloxacin-resistant isolates harbored quinolone resistance genes with aac(6′)-Ib-cr as the most common.