Prevalence of group B Streptococcus (GBS) Colonization in antenatal Women at Kenyatta national Hospital (KNH)

Abstract

Background Group B streptococcus (GBS; Streptococcus agalactiae) is a gram-positive coccus and approximately 10-30% of women worldwide carry it in their urogenital or lower gastrointestinal tract. It is a leading cause of perinatal morbidity and mortality and a common cause of maternal peripartal infections in some developed countries. In Kenya, however, the spectrum of GBS disease remains a largely under-recognised problem. Prophylactic treatment is easily achieved with penicillin G which is accessible at low cost at Kenyatta National Hospital (KNH) with excellent gains In neonatal and maternal health. Objective: To determine the prevalence of GBS among antenatal women at KNH and assess associated risk factors. Study Deign: A cross-sectional descriptive study. Setting: KNH antenatal clinic. Study Population: Pregnant women attending the antenatal clinic at KNH. Methodology: A total of 322 consenting pregnant women >35 weeks gestation by dates with no history of antibiotic use within the, two weeks prior to the study and no current per vaginal bleeding were recruited into the study. Swabs for culture of group B streptococcus (GBS) were obtained from the lower vagina and the anorectal canal. A second smear was taken from the walls of the lower vagina for microscopic examination of bacterial vaginosis. Antenatal profile data such as HIV, VDRL, and HB were extracted from patients' files. Data entry and analysis was carried out using EPI-Info 3.3 and SPSS Version 13 respectively. A p-value of less than 0.05 was considered statistically significant. Results The mean age of the mothers was 28.2 (+5) with a range of 18 to 45 years. Majority of the women were married (90.3%), had at least secondary level of education (81%) and were employed (62.3%). Slightly over 60% were multigravid. About 29% of those who were multi-gravid reported history of still birth. GBS was isolated in 81 (25.2%) of the participants. The anorectal colonization was greater (21.2%) than vaginal colonization (14%), however, isolation of GBS in the vaginal cavity was significantly associated with isolation in the anorectal canal, p= <0.0001. GBS colonization was significantly associated with History of still birth, (p = 0.011). No significant association was found between GBS colonization and age, parity, employment and level of education. Similarly no significant association was found between GBS colonization and HIV status, bacterial vaginosis, and history of other bad pregnancy outcomes such as preterm delivery, early neonatal death, early neonatal sepsis, premature rupture of membranes (PROM) and fever in previous pregnancy. Conclusions and recommendations A quarter of the mothers attending antenatal clinic at KNH are GBS colonized a figure that is comparable to findings in other parts of the world. GBS colonization is significantly associated with history of still birth. We therefore advocate for access to GBS screening for high risk mothers in our unit. We recommend a follow up study to determine the impact of GBS colonization on maternal and perinatal morbidity and mortality and the cost effectiveness of universal antenatal screening in our set-up.