[Differences between oral and intestinal microorganisms of 860 children aged 1-6 years in Nanjing city]

To explore the differences between oral and intestinal microorganisms of 860 children aged 1-6 years in Nanjing city.

Eight hundred and sixty children aged 1-6 years who met the inclusion criteria were enrolled. 860 saliva samples and equivalent stool samples were collected. Microbial DNA was extracted and amplified using PCR. High-throughput sequencing was performed using Miseq sequencer, and bioinformatics analysis was performed to compare the differences of oral and intestinal microflora. SPSS 20.0 software package was used to perform the statistical analysis.

At phylum level, Bacteroidetes (39.98%), Proteobacteria (25.32%) and Firmicutes (21.78%) were the most common microbes in oral cavity, while Firmicutes (45.21%) and Bacteroidetes (37.21%) were the most abundant microbes in the gut. At genus level, the top three microbes in the oral cavity included Prevotella(26.11%), Neisseria (12.39%), Porphyromonas(10.13%), while the top three microbes in the gut included Bacteroidetes(20.11%), Prevotella (9.13%), and Faecalibacterium (5.13%). There were significant alpha and beta differences in oral and intestinal microbial diversity.

Bacteroidetes and Proteobacteria are the dominant species in the oral cavity, while Firmicutes and Bacteroidetes are the dominant species in the gut. There are significant differences in species composition and abundance between oral and intestinal microorganisms.