Group B Streptococcus Colonization In pregnancy

Abstract

Group B streptococcus (GBS) can colonize the female genital tract and can transmit to the neonate causing early onset or late onset infections. Identification of the GBS colonization is important in prevention of infections. Very few studies have been published in Sri Lanka in this area. Objectives of the study were to find out the prevalence of Group B Streptococcus colonization in pregnant women, to compare the GBS vaginal colonization rate with the rectal colonization in pregnancy and to find out the sensitivity of above GBS isolates. This study was carried out from August to November 2011. Lower vaginal and rectal swabs were collected separately from pregnant women with gestational age of 35 to 37 weeks who were attending to the obstetric clinics in Teaching Hospital Peradeniya after getting consent. Swabs were enriched separately using Todd Hewitt broth supplemented with antibiotics and incubated at 35 - 37⁰C for 18 - 24 hours. Enriched broth was cultured onto blood agar, incubated and suspected colonies were identified with Gram stain, catalase test and Lancefield's grouping. The sensitivity was performed for penicillin, erythromycin and clindamycin by using Stokes method and MIC was performed for penicillin whenever the disc diffusion result was intermediately sensitive or resistant. According to the study, GBS colonization in pregnancy in the study sample was 30%. Out of 100 pregnant mothers, GBS were recovered from both vaginal and rectal swabs in 20. GBS was isolated only from vaginal swabs in 04 mothers and only from rectal swabs in 06 mothers. Rectal GBS colonization was 26% and it was higher than the vaginal colonization rate, which was 24%. The sensitivity to penicillin was found to be 100% while the sensitivity to erythromycin and clindamycin were 63.33% and 30% respectively. This implies the need of routine GBS screening in pregnancy in the study population and it is important to collect both vaginal and rectal swabs for GBS screening in pregnancy.