Weight Shapes the Intestinal Microbiome in Preterm Infants: Results of a Prospective Observational Study
Abstract Background: The intestinal microbiome in preterm infants differs markedly from term infants. It is unclear whether the microbiome develops over time according to infant specific factors. Methods: We analysed (clinical) metadata - to identify the main factors influencing the microbiome composition development - and the first meconium and feacal samples til the 4th week via 16S rRNA amplican sequencing. Results: We included 41 infants (gestational age 25-30 weeks; birth weight 430-990g. Birth via Caesarean section (CS) was associated with placental insufficiency during pregnancy and lower BW. In meconium and in weeks 2 and 3 an increased combined abundance of Escherichia and Bacteroides (maternal fecal representatives) was associated with vaginal delivery (p=0.021, p=0.0002, p=0.028, respectively) while Staphylococcus (skin microbiome representative) was associated with CS (p=0.0008, p=0.0003 p=0.046, respectively). Secondly, irrespective of the week of sampling or the mode of birth, a transition was observed as children children gradually increased in weight from a microbiome dominated by Staphylococcus (Bacilli) towards a microbiome dominated by Enterobacteriaceae (Gammaproteobacteria). Conclusions: Mode of delivery affects the meconium microbiome composition. It also suggests that the weight of the infant at the time of sampling is a better predictor for the stage of progression of the intestinal microbiome development/maturation than postconceptional age.