Prevalence of Antibiotic Resistance Genes in Clinical Isolates of Staphylococcus Aureus From Women With Urinary Tract Infections in Lagos State

Staphylococcus aureus has been implicated ins urinary tract infection (UTI) in humans. Virulence and drug resistance play important roles in the pathogenesis of Staphylococcus aureus infections. The objectives are to establish the antibiotic susceptibility and resistance patterns of clinical isolates of S. aureus, and to demonstrate the presence of antibiotic resistance genes among the isolates. Isolates were examined for susceptibility to 15 antibiotic disks using the disk diffusion method and for possession of resistance genes by polymerase chain reaction. Data were analyzed using SPSS software version 16.0. The relationship between antibiotic resistance genes and antibiotic susceptibility was determined using Pearson's Chi-square test. All 50 isolates were resistant to at least three antibiotics. Fifteen isolates (30%) exhibited the highest multiple antibiotic resistance (MAR) index value of 0.7. The most effective antibiotics were mipenem, levofloxacin, ciprofloxacin, ofloxacin, and gentamicin and the least effective were cloxacillin, oxacillin, and augmentin. The most prevalent resistance gene of the 50 isolates was mecA (80.5%), followed by femB (50%), blaZ (11.1%), ermA (16.7%), and aac(6')-aph(2') (5.6%). The correlation between genotype (absence or presence of a major resistance gene) and phenotype (susceptibility or reduced susceptibility) was high for penicillin and the presence of mecA (98%), and femB (97%). In contrast with the other resistances, the agreement between genotypes and phenotypes for erythromycin and the presence of ermA was poor (66%), gentamicin and the presence of aac(6')-aph(2"') (41%). The results indicate that there is a need for surveillance programmess to monitor drug resistance in pathogenic Staphylococcus aureus.