Investigation into the gut microbiota of infants in the INFANTMET study at years one, two and four of life. INFANTMET Years 1-4

BackgroundPreviously we described the gut microbiome development over the first 24 weeks of life in the INFANTMET cohort (Hill et al., 2017). We demonstrated that mode of delivery, gestational age at birth and prolonged breastfeeding had significant effects on the microbiota composition over the first 24 weeks. The aim of this study was to further characterise the gut microbiota of the INFANTMET cohort up to four years of age. MethodsStool samples were collected from the INFANTMET cohort at one, two and four years of age and DNA was extracted from 0.2g of sample. The V4-V5 region of the 16S rRNA gene was sequenced using the Illumina MiSeq platform. ResultsAlpha diversity increased with age after birth. Redundancy analysis determined a significant impact of gestational age at birth (p=0.05) and delivery mode (p=0.039). Bacteroidetes were significantly higher in those born full term (FT) compared with PT (PT) and in those born via Spontaneous Vaginal Delivery (SVD) compared with Caesarean section (CS) birth mode at one year old. At year two, Streptococcaceae were significantly more abundant in children born PT than FT. In contrast to year one, Bacteroidetes were significantly more abundant in the PT group at four years of age. LEfSe identified Escherichia-Shigella and Bifidobacterium to have the greatest discriminatory effect at year one, Lachnospiraceae_UCG008 at year two and Christensenellaceae and Ruminococcaceae at year four. DiscussionThis study demonstrates how early life factors including delivery mode and gestational age at birth exert significant effects on the gut microbiota that are retained in the early years of life. An altered gut microbiota in the early years may alter the individual’s risk of developing obesity or atopic disease later. Thus, by understanding the changes to the gut microbiota in the early years it may enable researchers to identify pivotal time points whereby therapeutic interventions could be beneficial to ensure optimum health outcomes.