Infant gut microbiota and food sensitization: associations in the first year of life

BackgroundThe gut microbiota is established during infancy and plays a fundamental role in shaping host immunity. Colonization patterns may influence the development of atopic disease, but existing evidence is limited and conflicting. ObjectiveTo explore associations of infant gut microbiota and food sensitization. MethodsFood sensitization at 1year was determined by skin prick testing in 166 infants from the population-based Canadian Healthy Infant Longitudinal Development (CHILD) study. Faecal samples were collected at 3 and 12months, and microbiota was characterized by Illumina 16S rRNA sequencing. ResultsTwelve infants (7.2%) were sensitized to 1 common food allergen at 1year. Enterobacteriaceae were overrepresented and Bacteroidaceae were underrepresented in the gut microbiota of food-sensitized infants at 3months and 1year, whereas lower microbiota richness was evident only at 3months. Each quartile increase in richness at 3months was associated with a 55% reduction in risk for food sensitization by 1year (adjusted odds ratio 0.45, 95% confidence interval 0.23-0.87). Independently, each quartile increase in Enterobacteriaceae/Bacteroidaceae ratio was associated with a twofold increase in risk (2.02, 1.07-3.80). These associations were upheld in a sensitivity analysis among infants who were vaginally delivered, exclusively breastfed and unexposed to antibiotics. At 1year, the Enterobacteriaceae/Bacteroidaceae ratio remained elevated among sensitized infants, who also tended to have decreased abundance of Ruminococcaceae. Conclusions and Clinical RelevanceLow gut microbiota richness and an elevated Enterobacteriaceae/Bacteroidaceae ratio in early infancy are associated with subsequent food sensitization, suggesting that early gut colonization may contribute to the development of atopic disease, including food allergy.