Epidemiology and Capsular Typing of Group B Streptococcus in Pregnant Women in Port Harcourt, Nigeria

Background: Colonization of the lower vagina and anorectum of pregnant women by group B streptococcus (GBS) in the third trimester is a risk factor for early neonatal disease. This study was carried out to determine the prevalence of rectovaginal colonization and capsular type distribution of GBS among pregnant women in Port Harcourt, Nigeria.

Methods: Group B streptococci were isolated and identified from vaginal and anorectal swabs using CHROMagar, CAMP test and latex agglutination while capsular typing was done using multiplex PCR.

Results: The prevalence of colonization was 18.9%. The capsular polysaccharide types detected by multiplex PCR were Ia, Ib, II, III, IV and V. Capsular types V and Ia were the most frequently occurring among the isolates at 32.6% and 21.7% respectively. While types IV and Ib were the least in frequency (8.7% and 2.2% respectively). A history of urinary tract infection and douching were identified by multiple logistic regression as risk factors for colonization.

Conclusion: Lower vaginal and anorectal colonization by group B streptococcus in late pregnancy is significant in this population. The capsular types Ia, Ib, II, III, IV and V, are similar in their occurrence and distribution to other reports from different parts of the world. Nigeria, therefore, would benefit from existing vaccine efforts, targeting the identified capsular types.

 Keywords: Group B streptococcus, capsular type, colonization, pregnant women, prevalence