Group B Streptococci (GBS) function both as common mucosal colonizers and as significant invasive pathogens in the neonatal period. Colonization of pregnant people can lead to vertical transmission and to either early-onset or late-onset disease in newborns. The balance between colonization and invasion is governed by bacterial virulence properties and the state of the neonatal host defense.
The introduction of intrapartum antibiotic prophylaxis (IAP) has led to a clear and substantial decline in the incidence of early-onset GBS sepsis. However, this intervention has not produced an equivalent reduction in late-onset sepsis. The review notes that late-onset disease accounts for as much as 50% of neonatal GBS cases, indicating that IAP alone does not address all pathways to invasive disease in infants.
IAP affects microbial colonization patterns in early life. Specifically, antibiotic exposure during labor is associated with reduced abundances of beneficial taxa such as Bifidobacterium and Bacteroides in infancy. The authors highlight concerns that these microbiome perturbations during a critical window of immune and metabolic development may be linked to later health outcomes, including increased risk of asthma and obesity. Given these potential downstream effects, the trade-offs of peripartum antibiotic use warrant careful consideration.
Multiple bacterial factors contribute to GBS capacity to adhere, cross barriers, and evade neonatal immunity. Among the virulence determinants discussed are GBS pilus islands, which promote adhesion and colonization, and the pore-forming toxin ß-hemolysin, which can disrupt epithelial or endothelial barriers. Surface structures such as the capsular polysaccharide and membrane glycolipids enable the pathogen to blunt or escape neonatal immune defenses. These molecular factors represent mechanistic targets to prevent bacterial translocation from colonization sites to sterile compartments, and thereby to reduce progression to invasive disease.
Neonatal host defenses against GBS are distinct from those of older children and adults. The review emphasizes that not only classical immune effector pathways but also the metabolic programming of neonatal immune cells influence outcomes. For example, the glycolytic capacity of immune cells can vary depending on the infecting GBS strain, implying that pathogen heterogeneity interacts with host cellular metabolism to shape disease risk and severity. These observations argue for preventive approaches that account for both bacterial strain differences and the metabolic/immune state of the newborn.
Given the demonstrated benefits of IAP for early-onset disease but its lack of effect on late-onset disease and the potential adverse impacts on the developing microbiome, the review calls for a reevaluation of neonatal GBS prevention strategies. Alternative or complementary approaches discussed include maternal or neonatal vaccination to prevent transmission and invasive disease, and probiotic supplementation aimed at restoring or supporting beneficial early-life microbiota. The authors advocate for more individualized prevention concepts informed by GBS strain characteristics and neonatal immune–metabolic status rather than reliance solely on broad peripartum antibiotics.
The review identifies key areas for future study: elucidating how GBS virulence determinants interact with neonatal immune ontogeny; understanding strain-specific effects on immune cell metabolic programming; and developing interventions that intentionally modulate the developing immune–microbiome interplay to favor host resistance. The authors stress that further research should aim to optimize prevention of both early- and late-onset disease while minimizing unintended consequences of current prophylactic practices.
Conclusion
This review synthesizes evidence that while IAP has reduced early-onset GBS disease, it does not address late-onset cases and alters infant microbiome composition in ways that may have long-term health implications. Multiple GBS virulence mechanisms and strain-specific effects on neonatal immune metabolism provide rationale for exploring targeted prevention strategies, including vaccination and probiotic approaches, and for prioritizing studies that seek to modulate host–microbiome development to protect vulnerable newborns. Details on specific vaccine candidates, probiotic strains, clinical trial results, or implementation pathways were not reported in the abstract and require consultation of the full review for comprehensive data.