Gut microbiota of healthy Canadian infants: profiles by mode of delivery and infant diet at 4 months

Abstract

Background: The gut microbiota is essential to human health throughout life, yet the acquisition and development of this microbial community during infancy remains poorly understood. Meanwhile, there is increasing concern over rising rates of cesarean delivery and insufficient exclusive breastfeeding of infants in developed countries. In this article, we characterize the gut microbiota of healthy Canadian infants and describe the influence of cesarean delivery and formula feeding.

Methods: We included a subset of 24 term infants from the Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort. Mode of delivery was obtained from medical records, and mothers were asked to report on infant diet and medication use. Fecal samples were collected at 4 months of age, and we characterized the microbiota composition using high-throughput DNA sequencing.

Results: We observed high variability in the profiles of fecal microbiota among the infants. The profiles were generally dominated by Actinobacteria (mainly the genus Bifidobacterium) and Firmicutes (with diverse representation from numerous genera). Compared with breastfed infants, formula-fed infants had increased richness of species, with overrepresentation of Clostridium difficile. Escherichia-Shigella and Bacteroides species were underrepresented in infants born by cesarean delivery. Infants born by elective cesarean delivery had particularly low bacterial richness and diversity.

Interpretation: These findings advance our understanding of the gut microbiota in healthy infants. They also provide new evidence for the effects of delivery mode and infant diet as determinants of this essential microbial community in early life.

Figure 1:

Composition of fecal microbiota in 24 healthy infants (mean age 4 mo), at the phylum (A) and family (B) level, by mode of delivery and diet. Each column represents 1 infant, as described in Table 1. BF − = no breastfeeding, BF + = exclusive or partial breastfeeding from birth until fecal sampling.

Figure 2:

Association of infant gut microbiota with mode of delivery and diet. We performed statistical comparisons using Spearman rank correlation (A and B), nonparametric analysis of variance followed by the Dunn post hoc test for multiple comparisons (D and E) and the Cochrane–Armitage χ² test for trend (C). NS = not significant.

Figure 3:

Exposures in early life, infant gut microbiota and future health. Colonization of the infant intestine is influenced by various factors.,,,, The resulting gut microbiota contributes to the development of the immune system, intestinal homeostasis and host metabolism., Disruption of the gut microbiota is associated with a growing number of diseases.,,–,–