Infant Gut Microbiome Linked to Reduced Risk of Viral Infections in Early Childhood

Recent research indicates that the composition of gut bacteria in infants, known as the microbiome, may play a crucial role in protecting against viral infections during early childhood. Conducted by researchers from the Wellcome Sanger Institute and University College London (UCL), this study represents the most extensive investigation into the microbiomes of UK infants to date.

The study revealed that infants at the age of one week with a specific combination of gut bacteria, predominantly found in those born vaginally, exhibited a lower likelihood of being hospitalized due to viral lower respiratory tract infections (vLRTI) within their first two years. Published in The Lancet Microbe, this research marks the first documented correlation between early gut microbiome composition and subsequent hospital admissions for respiratory illnesses in young children.

The researchers employed whole genome sequencing to analyze stool samples from 1,082 newborns and monitored their electronic health records to track hospital admissions up to the age of two. This builds upon earlier findings from the UK Baby Biome Study, suggesting that distinct microbiome profiles can confer various health benefits, including enhanced protection against viral infections.

Dr. Cristina Garcia-Mauriño, the first author of the study at UCL, noted that vLRTI is a leading cause of hospitalization among young children. The findings raise the possibility that certain early microbiome compositions may help mitigate this risk.

The gut microbiome is a complex ecosystem critical for human health and immune system development. It begins forming at birth, with the first month being a significant window for interventions that could enhance or restore the microbiome. Previous research indicated that infants born vaginally develop different microbiomes compared to those delivered via cesarean section (C-section), although these differences tend to diminish by the time the child reaches one year of age.

Earlier studies by the same research team identified that all UK infants possess one of three types of bacteria known as pioneer bacteria within their initial week of life. Two of these, Bifidobacterium longum and Bifidobacterium breve, are recognized for their beneficial effects in fostering a stable microbiome.

In this latest research, the team analyzed stool samples from 1,082 newborns to determine how these early gut bacteria might influence health outcomes in infancy. They compared the microbiome profiles against hospital admission records for vLRTI and found that infants born vaginally with higher levels of B. longum, along with other beneficial species like B. bifidum and B. dorei, had a reduced risk of requiring overnight hospital care for vLRTI. This correlation persisted even after considering factors such as antibiotic use and feeding methods.

However, the study also identified two other microbiome profiles among vaginally born infants that were associated with a higher risk of hospitalization for vLRTI. This suggests that not all infants born vaginally share the same protective microbiome composition, and further research is essential to explore the underlying factors.

While the study establishes an association rather than a direct cause-and-effect relationship, it emphasizes the need for larger studies to investigate the potential protective effects of B. longum and other beneficial bacteria on various health outcomes. The researchers plan to delve deeper into these questions in future research initiatives, including the upcoming Microbes, Milk, Mental Health and Me (4M) study.

Professor Nigel Field, a senior author of the study, stated that the findings highlight the link between specific infant microbiomes and a lower risk of respiratory infections, a connection made possible by the extensive scale of the Baby Biome Study and advanced genomic technologies.

Professor Louise Kenny, a noted investigator in related studies, acknowledged the complexity of childbirth decisions, emphasizing that while this study suggests vaginally born infants may experience lower rates of severe respiratory infections, more research is needed to develop tailored clinical recommendations.

Dr. Trevor Lawley, another senior author, highlighted the dynamic nature of infant microbiomes and their potential influence on health outcomes as children grow. This research underscores the role of early gut bacteria in infection protection and the potential for developing targeted probiotics to enhance early microbiome development.