Prevalence of vaginal group-b-streptococcus, antibiotic and antigen sensitivity amongst parturients at the Federal Medical Center Owerri, Nigeria

Abstract

Background: Group B streptococcus (GBS) is one of the principal agents of early onset neonatal sepsis, pneumonia and meningitis with significant morbidity for newborns and parturients.

Aim: This study was done to determine the prevalence of vaginal group B streptococcus amongst parturients in FMC Owerri. It also aimed to elucidate the antibiotic sensitivity of the strains of GBS isolated while comparing the sensitivity of antigen detection tests of GBS to culture.

Patients and Methods: This cross-sectional study was done at the labour ward and lying-in units of the Federal Medical Center, Owerri,from February 2015 to October, 2015. It involved one hundred and eighty (180) women recruited systematically. Two swab samples, high vaginal and rectal were collected from the parturients intrapartum and cultured. The babies were examined and weighed immediately after delivery, seen on the second and tenth days after delivery for features of fever or any other complaints.

Results: The overall prevalence of GBS amongst parturients was found to be 6.1%. Prevalence of vaginal colonization was 3.3% and that of the rectum was 2.8%, (2c=0.1282, df=1,p=0.502). Neonates with colonized mothers all had complaints of fever postpartum which was statistically significant (=55.86, df=1, p<0.001). All the microbes showed 100% sensitivity to penicillin G, erythromycin, gentamycin and ceftriaxone. Antibiotic resistance was discovered in augmentin (67%), Cloxacillin (55.6%) and ofloxacin (33.3%). Antigen detection tests gave Sensitivity=100%, specificity=96.4%, positive predictive value (PPV) = 64.7%, negative predictive value (NPV) =100%. Detection in both vaginal (=60.290,p=0.000) and rectal (=50.799,p=0.000) samples were statistically significant.

Conclusion: The prevalence of GBS in parturients in the Centre is low. Strains of GBS isolated amongst the sampled population in FMC Owerri had a high sensitivity to penicillin G, erythromycin, gentamycin and 3^rd generation cephalosporins. Antigen detection method for screening of GBS though very sensitive is however not specific with a significant false positive detection rate due to antigen cross reaction. It is however recommended that antigen detection be employed as intrapartum measure in high risk cases to reduce turnover time whilst supported by culture results later. There was associated significant neonatal sequaelae and further research to establish causal relationship will be advised.

Keywords: Prevalence, Group B streptococcus, colonization, antibiotic, antigen sensitivity