The establishment of the infant gut microbiota is a highly dynamic process dependent on extrinsic and intrinsic factors. We characterized the faecal microbiota of 4 breastfed infants and 4 formula-fed infants at 17 consecutive time points during the first 12 weeks of life. Microbiota composition was analysed by a combination of 16S rRNA gene sequencing and quantitative PCR (qPCR). In this dataset, individuality was a major driver of microbiota composition (P = 0.002) and was more pronounced in breastfed infants. A developmental signature could be distinguished, characterized by sequential colonisation of i) intrauterine/vaginal birth associated taxa, ii) skin derived taxa and other typical early colonisers such as Streptococcus and Enterobacteriaceae, iii) domination of Bifidobacteriaceae, and iv) the appearance of adultlike taxa, particularly species associated with Blautia, Eggerthella, and the potential pathobiont Clostridium difficile. Low abundance of potential pathogens was detected by 16S profiling and confirmed by qPCR. Incidence and dominance of skin and breast milk associated microbes were increased in the gut microbiome of breastfed infants compared to formula-fed infants. The approaches in this study indicate that microbiota development of breastfed and formula-fed infants proceeds according to similar developmental stages with microbiota signatures that include stage-specific species.

Antibiotic treatment in the first week of life is associated with an increased risk of wheezing and infantile colics. This study may provide a rationale for early cessation of antibiotics in neonates without proven or probable infection.

IntroductionImbalance of the human gut microbiota in early childhood is suggested as a risk factor for immune-mediated disorders such as allergies. With the objective to modulate the intestinal microbiota, probiotic supplementation during infancy has been used for prevention of allergic diseases in infants, with variable success. However, not much is known about the long-term consequences of neonatal use of probiotics on the microbiota composition. The aim of this study was to assess the composition and microbial diversity in stool samples of infants at high-risk for atopic disease, from birth onwards to six years of age, who were treated with probiotics or placebo during the first year of life.MethodsIn a double-blind, randomized, placebo-controlled trial, a probiotic mixture consisting of B. bifidum W23, B. lactis W52 and Lc. Lactis W58 (Ecologic® Panda) was administered to pregnant women during the last 6 weeks of pregnancy and to their offspring during the first year of life. During follow-up, faecal samples were collected from 99 children over a 6-year period with the following time points: first week, second week, first month, three months, first year, eighteen months, two years and six years. Bacterial profiling was performed by IS-pro. Differences in bacterial abundance and diversity were assessed by conventional statistics.ResultsThe presence of the supplemented probiotic strains in faecal samples was confirmed, and the probiotic strains had a higher abundance and prevalence in the probiotic group during supplementation. Only minor and short term differences in composition of microbiota were found between the probiotic and placebo group and between children with or without atopy. The diversity of Bacteroidetes was significantly higher after two weeks in the placebo group, and at the age of two years atopic children had a significantly higher Proteobacteria diversity (p < 0.05). Gut microbiota development continued between two and six years, whereby microbiota composition at phylum level evolved more and more towards an adult-like configuration.ConclusionPerinatal supplementation with Ecologic® Panda, to children at high-risk for atopic disease, had minor effects on gut microbiota composition during the supplementation period. No long lasting differences were identified. Regardless of intervention or atopic disease status, children had a shared microbiota development over time determined by age that continued to develop between two and six years.

BackgroundThe acquisition and development of infant gut microbiota can be influenced by numerous factors, of which early antibiotic treatment is an important one. However, studies on the effects of antibiotic treatment in early life on clinical outcomes and establishment and development of the gut microbiota of term infants are limited. Disturbed microbiota composition is hypothesized to be an underlying mechanism of an aberrant development of the immune system. This study aims to investigate the potential clinical and microbial consequences of empiric antibiotic use in early life.Methods/Design450 term born infants, of whom 150 are exposed to antibiotic treatment in early life and 300 are not (control group), are included in this observational cohort study with a one-year follow-up. Clinical outcomes, including coughing, wheezing, fever >38 °C, runny nose, glue ear, rash, diarrhea and >3 crying hours a day, are recorded daily by parents and examined by previously defined doctor’s diagnosis. A blood sample is taken at closure to investigate the infant’s vaccination response and sensitization for food and inhalant allergens. Fecal samples are obtained at eight time points during the first year of life. Potential differences in microbial profiles of infants treated with antibiotics versus healthy controls will be determined by use of 16S-23S rRNA gene analysis (IS-pro). Microbiota composition will be described by means of abundance, diversity and (dis)similarity. Diversity is calculated using the Shannon index. Dissimilarities between samples are calculated as the cosine distance between each pair of samples and analyzed with principal coordinate analysis. Clinical variables and possible associations are assessed by appropriate statistics.DiscussionBoth clinical quantitative and qualitative microbial effects of antibiotic treatment in early life may be demonstrated. These findings can be important, since there is evidence that manipulation of the infant microbiota by using pre- or probiotics can restore the ecological balance of the microbiota and may mitigate potential negative effects on the developing immune system, when use of antibiotics cannot be avoided.Trial registrationClinicalTrials.gov NCT02536560. Registered 28 August 2015.