Intrapartum antibiotics for GBS prophylaxis alter colonization patterns in the early infant gut microbiome of low risk infants

Abstract

Early life microbial colonization and succession is critically important to healthy development with impacts on metabolic and immunologic processes throughout life. A longitudinal prospective cohort was recruited from midwifery practices to include infants born at full term gestation to women with uncomplicated pregnancies. Here we compare bacterial community succession in infants born vaginally, with no exposure to antibiotics (n = 53), with infants who were exposed to intrapartum antibiotic prophylaxis (IAP) for Group B Streptococcus (GBS; n = 14), and infants born by C-section (n = 7). Molecular profiles of the 16 S rRNA genes indicate that there is a delay in the expansion of Bifidobacterium, which was the dominate infant gut colonizer, over the first 12 weeks and a persistence of Escherichia when IAP for GBS exposure is present during vaginal labour. Longer duration of IAP exposure increased the magnitude of the effect on Bifidobacterium populations, suggesting a longer delay in microbial community maturation. As with prior studies, we found altered gut colonisation following C-section that included a notable lack of Bacteroidetes. This study found that exposure of infants to IAP for GBS during vaginal birth affected aspects of gut microbial ecology that, although dramatic at early time points, disappeared by 12 weeks of age in most infants.

Figure 1

The effect of IAP exposure on microbial communities. (A) Beta diversity of bacterial profiles illustrated with principal coordinate analysis of Bray-Curtis dissimilarity. Samples were subset by age and IAP exposure is indicated. (B) Boxplots of phylum level abundance showing lower and upper quartiles along with the median value for relative abundance.

Figure 2

Longitudinal analysis of the effects of IAP during vaginal birth, using linear mixed models. (A) Alpha diversity over time of the gut microbiome in IAP unexposed and IAP exposed infants. (B) Abundance over time of bacterial genera significantly affected by IAP. Effects calculated with a linear mixed model that accounted for individuals over time; significance (p < 0.05) indicated as follows: (a) effect of IAP, (b) interaction of IAP and age, (c) effect of IAP duration, and d) interaction of IAP duration and age.