Prevalence of Group B Streptococcus colonization and serotype distribution among pregnant women in South Asian and African countries
Date
2024
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Witwatersrand, Johannesburg
Abstract
Background: Recto-vaginal Group B Streptococcus (GBS) colonization in pregnant women at the time of labour is the major risk-factor for developing invasive GBS disease within 7 days of age (early onset disease; EOD). We investigated prevalence of GBS recto-vaginal colonization at the time of labour among pregnant women and vertical transmission to their newborns across six African and two south-Asian countries.
Methods: This multi-country prospective, observational cross-sectional study was undertaken in six African [(Ethiopia (Adama city), Kenya (Kilifi), Mozambique (Manhica), Nigeria (Gwagwalada), Mali (Bamako) and South Africa (Johannesburg) and two Southeast Asian countries (Bangladesh (Mirzapur) and India (Vellore)]. Inclusion criteria included pregnant women 18 to 45 years of age, delivery at ≥37 weeks gestation and documented to be HIV-uninfected prior to study-enrolment. Lower vaginal swabs, rectal swabs and urine were collected from the mothers and separate skin surface swabs of the umbilicus, outer ear and axillary fold; and rectal and throat swabs were obtained from the newborn for GBS culture. Standardized sampling and culture using direct plating and selective broth media for detection of GBS colonization in the mother-newborn dyads was undertaken across the sites. Serotyping of GBS isolates was done in South Africa.
Results: Overall, 6,922 pregnant women were enrolled from January 10th , 2016 to December 11th , 2018. Of 6922 women who were enrolled, 6514 (94.1%; 759 to 892 per site) were included in the analysis. Overall, the prevalence of maternal GBS colonization was 24.1% (95%CI 23.1- 25.2; 1572/6514) being highest in Mali (41.1%, 95%CI: 37.7-44.6; 314/764) and lowest in Ethiopia (11.6%, 95%CI:9.5-14.1; 88/759). The overall rate of vertical transmission of GBS was 72.3% (95%CI 70.0-74.4; 1132/1566); being highest in Mozambique (79.2%, 95%CI 73.3-84.2); 168/212) and lowest in Bangladesh (55.8%, 95%CI 47.5-63.8; 77/138). The five
most common GBS colonizing serotypes were Ia (37.3%; 586/1572), V (28.5%; 448/1572), III (25.1%; 394/1572), II (9.2%; 144/1572) and Ib (6.5%; 102/1572). There was geographic variability in serotype proportion distribution. Serotype VII was the third most common serotype in India (8.5%, n=15/176) and serotype VI was mainly identified in Bangladesh (5.8%) and India (5.7%).
Conclusion: Our study reported high prevalence of GBS colonization in most settings, with some geographic variability even within African countries. Our findings suggests that there is likely to be a significant burden of EOD across the study sites. Post-licensure vaccine effectiveness studies should also focus on maternal GBS serotype distribution as non-vaccine serotype replacement could occur due to vaccine immune pressure
Description
A Research report submitted in fulfillment of the requirements for the degree of Masters in Public Health to the Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Johannesburg 2024
Keywords
Group B Streptococcus, Pregnant women, Colonization, UCTD
Citation
Kwatra, Gaurav. (2024). Prevalence of Group B Streptococcus colonization and serotype distribution among pregnant women in South Asian and African countries [Master’s dissertation, University of the Witwatersrand, Johannesburg]. WireDSpace.https://hdl.handle.net/10539/42700