Human Milk Oligosaccharides versus Streptococcus: How a Human-Made Natural Product Protects Us from Pathogens.

Group B Streptococcus (GBS) is a Gram-positive bacterium that colonizes the lower gastrointestinal tract, and in females, the urogenital tract, in up to 30% of healthy adults. However, GBS is a leading cause of mortality and morbidity in newborns due to ascending infection of the womb or by neonatal acquisition during vaginal passage. GBS neonatal disease manifests as pneumonia, sepsis, or meningitis, and an estimated 4 million newborns die each year globally. This commentary reflects on recent work by Mejia and colleagues (M. E. Mejia, S. Ottinger, A. Vrbanac, P. Babu, et al., mSphere 6:e00885-21, 2022, https://doi.org/10.1128/msphere.00885-21) that has examined human milk oligosaccharides (HMOs) as a natural product with anti-GBS activity. They show that HMOs reduce GBS vaginal colonization without impacting the normal vaginal microbiota. This study advances the possibility of using novel therapeutics to limit GBS maternal colonization and subsequent neonatal disease.