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. 2025 Mar 18;12(4):ofaf167.
doi: 10.1093/ofid/ofaf167. eCollection 2025 Apr.

Epidemiology of Group B Streptococcus: Maternal Colonization and Infant Disease in Kampala, Uganda

Mary Kyohere  1   2 , Hannah Georgia Davies  2   3 , Konstantinos Karampatsas  2 , Liberty Cantrell  4 , Philippa Musoke  1   5 , Annettee Nakimuli  6 , Valerie Tusubira  1 , Juliet Sendagala Nsimire  7 , Dorota Jamrozy  8 , Uzma Basit Khan  8 , Stephen D Bentley  8 , Owen B Spiller  9 , Caitlin Farley  9 , Tom Hall  2 , Olwenn Daniel  2 , Simon Beach  2 , Nick Andrews  10 , Stephanie J Schrag  11 , Clare L Cutland  12 , Andrew Gorringe  13 , Stephanie Leung  13 , Stephen Taylor  13 , Paul T Heath  2 , Stephen Cose  14 , Carol Baker  15 , Merryn Voysey  4 , Kirsty Le Doare  2   14 , Musa Sekikubo  6 ; PROGRESS Study Group
Collaborators, Affiliations

Epidemiology of Group B Streptococcus: Maternal Colonization and Infant Disease in Kampala, Uganda

Mary Kyohere et al. Open Forum Infect Dis. .

Abstract

Background: Child survival rates have improved globally, but neonatal mortality due to infections, such as group B Streptococcus (GBS), remains a significant concern. The global burden of GBS-related morbidity and mortality is substantial. However, data from low and middle-income countries are lacking. Vaccination during pregnancy could be a feasible strategy to address GBS-related disease burden.

Methods: We assessed maternal rectovaginal GBS colonization and neonatal disease rates in a prospective cohort of 6062 women-infant pairs. Surveillance for invasive infant disease occurred in parallel at 2 Kampala hospital sites. In a nested case-control study, we identified infants <90 days of age with invasive GBS disease (iGBS) (n = 24) and healthy infants born to mothers colonized with GBS (n = 72). We measured serotype-specific anticapsular immunoglobulin G (IgG) in cord blood/infant sera using a validated multiplex Luminex assay.

Results: We found a high incidence of iGBS (1.0 per 1000 live births) within the first 90 days of life across the surveillance sites, associated with a high case fatality rate (18.2%). Maternal GBS colonization prevalence was consistent with other studies in the region (14.7% [95% confidence interval, 13.7%-15.6%]). IgG geometric mean concentrations were lower in cases than controls for serotypes Ia (0.005 vs 0.12 µg/mL; P = .05) and III (0.011 vs 0.036 µg/mL; P = .07) and in an aggregate analysis of all serotypes (0.014 vs 0.05 µg/mL; P = .02).

Conclusions: We found that GBS is an important cause of neonatal and young infant disease in Uganda and confirmed that maternally derived antibodies were lower in early-onset GBS cases than in healthy exposed controls.

Keywords: anticapsular antibody; correlate of protection; group B Streptococcus; invasive disease; risk reduction.

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Conflict of interest statement

Potential conflicts of interest. All authors: No potential conflicts of interest.

Figures

Figure 1.
Figure 1.
Study cohort diagram. Abbreviations: GBS, group B Streptococcus; iGBS, invasive group B Streptococcus disease.
Figure 2.
Figure 2.
A, The percentage of different serotypes in group B Streptococcus (GBS) isolates from maternal colonization, and invasive GBS disease. B, The percentage of different clonal complexes in GBS isolates from maternal colonization, and invasive GBS disease. C, The percentage of different alpha-like protein genes in GBS isolates from maternal colonization, and invasive GBS disease. Abbreviations: alp, alpha-like protein; CC, clonal complex; CPS, capsular polysaccharide; NT, not typed.
Figure 3.
Figure 3.
A, Anti–capsular polysaccharide (CPS) immunoglobulin G (IgG) concentrations among infant case patients and controls for serotype Ia. B, Anti-CPS IgG concentrations among infant case patients and controls for serotype III. C, Anti-CPS IgG concentrations among infant case patients and controls for aggregated serotypes. The horizontal continuous line indicates the recently proposed threshold associated with 80% risk reduction. The horizontal dashed line indicates the recently proposed threshold associated with 90% risk reduction. Each point represents an individual sample. Yellow points indicate cord serum, and red points indicate infant serum collected during the acute phase of the disease.
See this image and copyright information in PMC

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