The article presents the results of a single study the intestinal microbiota of healthy infants. Study was performed 11 fecal samples, followed by targeted sequencing the amplified sites on the 16S rRNA gene Miseq platform (Illumina, USA), according to standard protocols. Total 600 unique OTU (operation taxonomic units), grouped into 7 bacterial phyla (Phylum) have been identified. Each sample had an average of 190±80 OTU at the species level. Established predominance of gram-positive anaerobic bacteria (71±23%). Quantitative phylum distribution was as follows: phylum Firmicutes – 43±15% (represented by Clostridium spp., Blautia spp., Lactobacillus spp., Enterococcus spp. and Veillonella spp.), The phylum Actinobacteria – 38±10% (of which more than 90% the OTU were represented Bifidobacterium spp.) and the phylum Proteobacteria – 15±8% (represented by the family Enterobacteriaceae). Representatives of phylum Bacteroidetes been identified (7–15%) in only three of eleven samples. All samples characterized by low species diversity, Shannon index and criterion α-diversity were in the range of 1,5–4,2, and 3–20, respectively. Children who are breastfed, observed a higher number of representatives of Proteobacteria, compared with children on artificial feeding. Noted the influence of adverse factors of pregnancy mothers (antibiotics, respiratory infection) on the composition of the intestinal microbiota of children, which reflected in the dominance of Klebsiella pneumoniae in one case, and the dominance of Enterococcus durans otherwise
