Microbes in Infant Gut Development: Placing Abundance Within Environmental, Clinical and Growth Parameters

Abstract

Sound and timely microbial gut colonization completes newborn's healthy metabolic programming and manifests in infant appropriate growth and weight development. Feces, collected at 3, 30, and 90 days after birth from 60 breastfed Slovenian newborns, was submitted to microbial DNA extraction and qPCR quantification of selected gut associated taxa. Multivariate regression analysis was applied to evaluate microbial dynamics with respect to infant demographic, environmental, clinical characteristics and first year growth data. Early microbial variability was marked by the proportion of Bacilli, but diminished and converged in later samples, as bifidobacteria started to prevail. The first month proportions of enterococci were associated with maternity hospital locality and supplementation of breastfeeding with formulae, while Enterococcus faecalis proportion reflected the mode of delivery. Group Bacteroides-Prevotella proportion was associated with infant weight and ponderal index at first month. Infant mixed feeding pattern and health issues within the first month revealed the most profound and extended microbial perturbations. Our findings raise concerns over the ability of the early feeding supplementation to emulate and support the gut microbiota in a way similar to the exclusively breastfed infants. Additionally, practicing supplementation beyond the first month also manifested in higher first year weight and weight gain Z-score.

Figure 1

(a,b) Relative quantification of bacteria by real-time PCR in the feces of newborns in the first 3 months. The box and whiskers plots represent the medians and interquartile ranges; error bars 10^th and 90^th percentiles, filled circles outliers. Asterisks denote significant differences between time-points (*p < 0.05; **p < 0.01). The results are presented as a number of group specific bacterial DNA copies in g of feces (a), as ratio group specific DNA/all bacterial DNA (%) (b).

Figure 2

(a,b) Principal component analysis (PCA) with varimax rotation of the fecal microbiota in infants. Loadings of relative bacterial abundances (a). This figure shows the two primary principal components, which explain 32.8% and 16.2% of data variation. Individual PCA scores at 3, 30, and 90 days after birth (b).

Figure 3

Diagram presenting values for the exposed significant associations between the infant growth parameters and presumptive perinatal growth confounders.