Effect of environmental exposure on infant gut microbiota composition and diversity in the Canadian Healthy Infant Longitudinal Development (CHILD) national birth cohort

Abstract

Background: The development of infant gut microbiota plays a crucial role in immune system development, and infant gut microbiota dysbiosis has been linked to asthma and allergic disease. Studies have shown that Bacteroidetes phylum was less abundant in the guts of allergic children. Although extensive research has been conducted to investigate the effects of delivery mode and infant feeding on gut mircobiota, not much is known about the influence of hospital microbial environment and exposure to household cleaning products on infant gut microbiota composition and diversity. Objective: To assess the impact of exposure to hospital microbial environment and household cleaning products, on the infant gut microbiota composition and diversity. Methods: Fecal samples from a subset of 787 children from the Edmonton, Winnipeg and Vancouver sites of the Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort were included in the study. Infant hospital length-of-stay after birth was obtained from birth chart reviews and parent report at 3 months postpartum. Personal use of household cleaning products namely: disinfectant (multi-surface cleaner), detergent and other chemicals (spray air-freshener) were obtained from mothers at 3 months post-delivery. Infant gut microbiota at 3-4 months was characterized by Illumina 16S rRNA sequencing. Microbial relative abundance, Shannon diversity and Chao1 species richness were determined. Results: Newborn exposure to the hospital environment for more than one day was associated with higher fecal abundance, at infant age 3-4 months, of microbes belonging to the Lachnospiraceae family (p=0.041). In addition, Pseudomonadaceae (p=0.04) and genus Pseudomonas (p=0.027) were more abundant in the gut of infants with extended hospital stays after birth, in both vaginally and caesarean-delivered infants. High indoor disinfectant exposure was associated with low fecal abundance of Actinobacteria (p=0.0002) at the phylum level and of Bifidobacteriaceae (p=0.0003) at the family level. Moreover, total microbial diversity was reduced at the order level (p= 0.028) in infants in the high exposure group. Conclusion: The findings provide evidence of gut microbiota dysbiosis associated with exposure to hospital microbial environment and household cleaning products. The impact of these compositional changes on the development of gut immunity and atopic disease later in life requires further study.