Evaluation of the Prevalence, Antimicrobial Resistance Trait, and Virulence Determinants in Staphylococcus aureus Isolates from the Anogenital Area of 35-37 Weeks Pregnant Women

Abstract

Staphylococcus aureus is a major pathogen in the postpartum period being frequently implicated as a cause of mastitis, and nursery outbreaks, among others as well as its increasing resistance to common antibiotics. This study therefore aimed at evaluating the presence of S. aureus in pregnant women attend¬ing clinics in rural towns in Eastern Cape, South Africa. A total of 82 pregnant women at 35‒37 weeks of gestation were sampled for the presence of S. aureus. Using standard microbiological methods, presump¬tive S. aureus isolates were obtained from vaginal and rectal swab samples. The isolates were confirmed by conventional polymerase chain reaction and then tested for antimicrobial susceptibility using the disc diffusion technique. Presence of resistance genes and virulence determinants were equally profiled. A to¬tal of 47 (57.3%) out of 82 pregnant women were colonized with S. aureus. Only two virulence genes PVL- 37/47 (78.7%) and eta-10/47 (21.3%) were detected in the isolates. The isolates were all resistant to penicillin G and clindamycin (100%), while resistances to tetracycline, vancomycin, rifampicin were 71% and resistance to oxacillin and erythromycin were above 80% while resistance to other antibiotics tested were below 40%. The isolates showed multiple resistance to 5-6 antimicrobials with indices ranging from 0.5-0.6. Genes encoding resistance to erythromycin (ermB), tetracycline (tetM), and rifampicin (rPOB) were found in 72.7% (34/47) of the isolates, while 15% (7/47) possessed the Bla-Z (penicillin). The high antibiotics resistance traits found in the isolates analysed indicates limited therapeutic options and portents a major threat to public health.