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Maternal group B Streptococcus (GBS) colonization is a major risk factor for neonatal GBS infection. However, data on GBS are scarce in low- and middle-income countries. Using sociodemographic data and vaginal swabs collected from an international cohort of mothers and newborns, this study aimed to estimate the prevalence of GBS colonization among pregnant women in Madagascar (n = 1, 603) and Senegal (n = 616). The prevalence was 5.0% (95% CI, 3.9-6.1) and 16.1% (95% CI, 13.1-19.0) in Madagascar and Senegal, respectively. No factors among sociodemographic characteristics, living conditions, and obstetric history were found to be associated independently with GBS colonization in both countries. This community-based study provides one of the first estimates of maternal GBS colonization among pregnant women from Madagascar and Senegal.
BIRDY is a multicenter cohort study launched to address the lack of epidemiological data concerning drug-resistant neonatal and infantile bacterial infections in LMICs.14 As part of the project, our study included pregnant women in Antananarivo (an urban setting with three districts near Institut Pasteur de Madagascar; 4,100 women of reproductive age according to a local census) and Moramanga (a rural setting with six districts; 3,800 women of reproductive age) in Madagascar, and in Guédiawaye (an urban setting within the Wakhinane Nimzatt district; 4,000 births/year) and Sokone (a rural setting with14,500 inhabitants) in Senegal (Figure 1). At each study site, pregnant women were recruited consecutively via the local primary health-care center—which covers the selected districts, door-to-door home visits by “matrons” (influential women within the local communities who play a role in pregnancy follow-up and delivery), and investigators within the selected locations—during their third trimester of pregnancy or at delivery, at which point a lower vaginal swab was collected to screen for GBS colonization. Health-care workers (nurses and midwives) and collaborating matrons were trained for the project. Recruitment occurred from September 2012 to December 2016 in Madagascar. In Senegal, women were recruited from October 2013 to December 2018. In our study, we only included women from the cohort who underwent an effective GBS screening. Study sites maps. This figure appears in color at www.ajtmh.org. Collected variables were as follows: 1) sociodemographic factors (age, marital status, education, and employment), 2) living conditions (access to electricity, type of sanitation [indoor latrines and outdoor pour-flush latrines were considered as improved sanitation], number of people living under the same roof), 3) brachial circumference to determine nutritional status (undernutrition if < 24 cm15), 4) obstetric history (gravidity/parity, history of child death/stillbirth/miscarriage), 5) pregnancy follow-up information (number of antenatal consultations, professional pregnancy follow-up [physician, midwife, or nurse], and 6) medication during the current pregnancy (antibiotic consumption; iron/folate supplementation; intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine [IPTp-SP], defined as an intake of at least one dose during pregnancy; number of doses of IPTp-SP; mosquito net use). The case report form is presented in Supplemental Figure 1. Collected data underwent quality assessment initiated both locally and centralized by the project’s data manager (Institut Pasteur). Paper data entry forms were reviewed, and errors and inconsistencies were corrected by clarifying with the source. Trained personnel collected the samples using sterile dry swabs in health-care facilities or at home. All samples were transported without transport medium to Institut Pasteur laboratories then stored in refrigerators before GBS screening was conducted. Isolates were plated onto a selective growth medium—BD Group B Streptococcus Differential agar (Granada Medium, Becton Dickinson, Franklin Lakes, NJ, a proteose peptone starch agar with 3-[N-morpholino]propanesulfonic acid, which is a buffering agent] and phosphate, and supplemented with methotrexate and antibiotics) in Senegal and BD Colombia colistin and nalidixic acid (CNA) agar (Becton Dickinson, Franklin Lakes, NJ) with 5% sheep blood in Madagascar—and incubated for 24 to 48 hours at 37°C in 5% carbon dioxide (anaerobic incubation for Granada Medium). In Senegal, the colonies were identified by morphological determination and a latex agglutination test (SLIDEX® Strepto Plus, bioMérieux, Marcy-l’Étoile, France). In Madagascar, the colonies were identified by morphological determination, beta hemolysis, and directly by matrix-assisted laser desorption/ionization–time of flight mass spectrometry (MALDI Biotyper®, Bruker Daltonics, Billerica, MA). Because Senegalese and Malagasy study population characteristics—demographics, socioeconomic background, cultural practices, and habits—and prevalence of maternal GBS colonization differed substantially, separate analyses were carried out. Quantitative variables were expressed as median (interquartile range); qualitative variables were expressed as a percentage and a 95% CI for GBS colonization prevalence. The GBS-positive versus GBS-negative groups were compared using the χ2 test or Fisher’s exact test for qualitative variables, and Wilcoxon rank-sum test for quantitative variables. Factors associated potentially with maternal GBS colonization were selected based on prior knowledge.16–18 Because of the important number of missing values concerning antibiotic consumption during pregnancy, this variable was not included in the analysis. The selected variables were first assessed in a univariate analysis and were then included in a logistic regression with backward elimination if the P value was less than 0.25. When two or more variables were correlated, the variables with the smaller P value were retained (age, gravidity, and parity). The significance threshold was fixed at 0.05. Statistical analyses were performed using Stata 14.0 (StataCorp LLC, College Station, TX). The BIRDY protocol was approved by the relevant national ethics committees for health research of Madagascar (068-MSANP/CE), Senegal (SEN 14-20) and France (IRB/2016/08/03, Institut Pasteur). Women were included after receiving information about the project, agreeing to biological sampling on themselves and their newborns, and signing an informed consent form. BIRDY provided free-of-charge tests and treatments of infantile infections during the follow-up period. BIRDY data collection has been declared to the Commission nationale de l’informatique et des libertés (a French national data protection authority), in accordance with French law.
