Three main factors define changes in fecal microbiota associated with feeding modality in infants.

OBJECTIVES: There are many differences in the fecal infant microbiota associated with various feeding methods. The aim of this study was to examine the major differences in the fecal microbiota of breast-fed (BF) and formula-fed (FF) infants and to describe the principal bacterial components that would explain the variability in the predominant bacterial families and genus clusters. METHODS: Fecal samples from 58 infants, 31 of whom were exclusively BF and 27 of whom were exclusively FF with a standard formula in agreement with the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition recommendations, were analyzed by fluorescent in situ hybridization combined with flow cytometry. Principal component analysis was used to maximize the information gained for the predominant bacterial families and genus clusters using a minimal number of bacterial groups. RESULTS: The predominant detected group was Bifidobacterium, followed by Enterobacteriaceae and Bacteroides in both BF and FF infants. The Lactobacillus group was the only independent variable associated with FF infants. We also found that 3 principal components were sufficient to describe the association between the bacterial group, genus, and species studied in BF and FF infants; however, these components differed between BF and FF infants. For the former, the 3 factors found were Bifidobacterium/Enterobacteriaceae, Lactobacillus/Bacteroides, and Clostridium coccoides/Atopobium; for the latter, Bifidobacterium/Enterobacteriaceae, Bacteroides and C coccoides were observed. CONCLUSIONS: There is a clear clustering of components of infant microbiota based on the feeding method.

Safety and immunomodulatory effects of three probiotic strains isolated from the feces of breast-fed infants in healthy adults: SETOPROB study.

UNLABELLED: We previously described the isolation and characterization of three probiotic strains from the feces of exclusively breast-fed newborn infants: Lactobacillus paracasei CNCM I-4034, Bifidobacterium breve CNCM I-4035 and Lactobacillus rhamnosus CNCM I-4036. These strains were shown to adhere to intestinal mucus in vitro, to be sensitive to antibiotics and to resist biliary salts and low pH. In the present study, a multicenter, randomized, double-blind, placebo-controlled trial with 100 healthy volunteers in three Spanish cities was carried out to evaluate the tolerance, safety, gut colonization and immunomodulatory effects of these three probiotics. Volunteers underwent a 15-day washout period, after which they were randomly divided into 5 groups that received daily a placebo, a capsule containing one of the 3 strains or a capsule containing a mixture of two strains for 30 days. The intervention was followed by another 15-day washout period. Patients did not consume fermented milk for the entire duration of the study. Gastrointestinal symptoms, defecation frequency and stool consistency were not altered by probiotic intake. No relevant changes in blood and serum, as well as no adverse events occurred during or after treatment. Probiotic administration slightly modified bacterial populations in the volunteers' feces. Intestinal persistence occurred in volunteers who received L. rhamnosus CNCM I-4036. Administration of B. breve CNCM I-4035 resulted in a significant increase in fecal secretory IgA content. IL-4 and IL-10 increased, whereas IL-12 decreased in the serum of volunteers treated with any of the three strains. These results demonstrate that the consumption of these three bacterial strains was safe and exerted varying degrees of immunomodulatory effects. TRIAL REGISTRATION: ClinicalTrials.gov NCT01479543.