Correlates of Vaginal Colonization with Group B Streptococci among Pregnant Women

Background: A study of genital colonization by group B streptococcus (GBS) was conducted in pregnant women in their third trimester, which is a known risk factor of morbidity and mortality among newborns. Aims: The present study was undertaken to study the prevalence and the correlates of vaginal colonization by GBS among pregnant women. Setting and Design: This observational cross-sectional study was conducted during September 2002 to March 2004 on 524 pregnant women. Materials and Methods: Three high vaginal swabs were obtained from all the pregnant women admitted at term and in preterm labor. Two swabs were used for aerobic culture and the third one for gram staining. The first set of swabs was cultured on 5% Sheep blood agar plates. The second set of swabs were inoculated into Todd-Hewitt broth and then subcultured in 5% Sheep blood agar plates. The main outcome measures were the presence of GBS infection in comparison to the age group, gravida, gestational age, premature rupture of membrane (PROM), preterm labor and association with febrile spells of the present pregnancy. Results: The culture positivity rate of GBS was 4.77% and coexistent organisms isolated were Candida species (36%), Staphylococcus aureus (8%) and Enterococcus species (8%). Culture positivity in the age group of 18-25 years was 5.71%, of which 5.74% were in their first pregnancy. The correlation between age group and gravida with GBS culture positivity was statistically insignificant. The culture positivity in <36 weeks of gestational age was 6.93%. This relation was statistically significant. Twenty-eight percent developed PROM. Sixty-four percent of culture positives had preterm labor. Conclusion: GBS infection among pregnant women was significantly correlated with the gestational age, PROM and preterm labor. In pregnancy GBS colonization causes asymptomatic bacteriuria or UTI. It is a well known cause of puerperal infections with amnionitis, endometritis and sepsis being the most commonly reported infections.