Prevalence and microbiological epidemiology of Group B streptococci and other opportunistic pathogens among mothers and neonates in Nepal: A prospective cross-sectional study

Funders:
MORU–OUCRU Discovery Research Academy, MODRA (Wellcome Trust)

Coinvestigators:
Associate Professor Abhilasha Karkey
Shreena Shrestha, Gynecologist and Obstetrician, Siddhi Memorial Maternity and Children Hospital (SMH)
Raj Kumar Shrestha, Clinical Microbiologist, Siddhi Memorial Maternity and Children Hospital (SMH)
Stuart Blacksell, Professor, Department of Tropical Microbiology, Mahidol Oxford Tropical Medicine Research Unit (MORU)
Claire Chewapreecha, Wellcome International Intermediate Fellow, Mahidol Oxford Tropical Medicine Research Unit (MORU

Group B Streptococci (GBS) is a Gram-positive bacterium causing severe infections in newborns, including sepsis, pneumonia, meningitis, and encephalopathy. Around 10–30% of pregnant women carry GBS asymptomatically, and newborns often contract it during birth. Antibiotics given to colonized mothers at delivery reduce transmission but may contribute to antibiotic resistance and disrupt the newborn’s microbiome. Maternal vaccines offering passive immunity are a promising alternative, but current vaccine candidates primarily target strains prevalent in high-income countries, potentially limiting their effectiveness in rest of the world, where disease epidemiology is poorly understood. Data on GBS burden (carriage and infection) and serotypes is scarce, especially in South Asia, including Nepal, due to the absence of routine screening and detection challenges. This study aims to assess GBS carriage in late pregnancy and infections in newborns, guiding local antenatal screening policies. Data on specific serotype variants of colonizing GBS will also be identified which will help develop vaccines tailored to the Asian context.

Background

Maternally transmitted infections significantly contribute to neonatal morbidity and mortality but remain underexplored. Group B Streptococcus (GBS) is a major cause, colonizing ~18% of pregnant women in high-income countries, leading to neonatal colonization and, in 1–2% of cases, severe infections. The global incidence is 0.49/1000 live births, highest in Africa (1.12) and lowest in South Asia (0.02), with limited data from Nepal. This stark contrast warrants further investigation. Regional differences in GBS maternal carriage and neonatal sepsis may stem from several factors. Limited studies and the absence of routine antenatal screening in South Asian LMICs lead to incomplete case detection. Diagnostic limitations, such as suboptimal culture methods, may contribute to underreporting. This study aims to address gaps in GBS prevalence, serotypes, and antimicrobial resistance in Nepal, focusing on maternal colonization and vertical transmission. Findings will inform local antenatal screening guidelines and support vaccine development by highlighting regional serotype variations, enhancing global coverage.

Primary objective:

To determine prevalence and serotypes of GBS causing maternal and neonatal colonization in a community-based maternity and children hospital of Nepal

Secondary objectives:

To determine prevalent serotypes of GBS causing invasive infections among women and neonates
To determine clinical, demographic and bacteriological features of GBS
To determine microbiological features of potentially pathogenic bacteria other than GBS causing maternal/neonatal colonization