Composition Of Faecal Microbiota And Beta-lactam Antibiotic Effects On Intestinal Microbiota In Children

Objective:To explore the composition of intestinal microbiota in children with or without treated with beta-lactam antibiotic in one week.Methods:The faecal samples were collected from10children subjects aged between3-5years old without used antibiotics in1month as the control group and4subjects in the same age used the beta-lactam antibiotic in1week as antibiotic used group. The genomic DNA was extracted from faecal samples respectively and the segment of about540bases from16S rRNA gene was amplified by PCR with universal primers. The amplicon was ligated into the pTZ57R/T vector and then transformed in E.coli strain DH5α to construct16S rDNA clone library.160clones for each sample were randomly picked and sequenced. All sequences were aligned by BLAST and classified with RDP classifier. The sequences with≥97%identity were designated as the same genus. The phylogenetic trees were created by Neighbour-Joining analysis (MEGA5.0).Results:The dataset of control group is constitutive of1317sequences from10samples and antibiotic used group is constitutive of536sequences from4samples. Aggregate microbiota is composed of Firmicutes and Bacteriodetes, Proteobacteria, Actinobacteria and Fusobacteria at phylum level in children’s fecal samples. The dominated microbiota are phyum Firmicutes with average proportion of55.2%and phylum Bacteriodetes with average prepotion of42.9%. The microbiota composition both control group and antibiotic used group is similar. However, the individual composition datasets show extraordinary variation.Conclusions:The feacal dominant microbiota of children is composed of phylum Firmicutes with an average proportion of55.2%and phylum Bacteriodetes with an average proportion of40.9%. The predominant genera are composed of Faecalibacterium (53%), Roseburia (8.5%) and Lachnospiraceae incertae sedis (6.2%) at phylum Firmicutes, and Prevotella (47.2%), Bacteroides (42.8%) at phylum Bacteriodetes. For individual subject, there is dramatic interindividual variability of the intestinal microbiota. In four subjects treated with beta-lactam antibiotic in1week, the microbiota composition has no significant differences at phylum and genus level compared with the control group.