BACKGROUND/PURPOSE: Infant oral microbiome theoretically could serve as the seeding microorganisms in its own gut microbial construction from anatomical perspective. The purpose of this study was to investigate the relationship between oral and gut microbiota in early infantile life. METHODS: This prospective longitudinal study included 15 healthy babies delivered in a single medical center during 2019∼2023. Stool samples were collected daily in the first 5 days after birth, while salivary and buccal mucosal samples were obtained once. All three samples continued acquisition at the end of 1st, 2nd, 4th and 6th month of age. The entire samples were 16S-rRNA sequenced. Investigation of the shared bacteria between oral and gut ecosystems was carried out. RESULTS: Niche differentiation started very early in the infants' gut ecosystem since the 2nd day of life. Bifidobacterium appeared scarcely in the first 5 days after birth but gradually rose in abundance since the 1st month. The compositions of the infant salivary and buccal mucosal microbiome were similar. Most of the infant gut and oral microbiota evolved independently, whereas the oral Rothia, Prevotella and Veillonella correlated with the development of their gut counterparts. Coprococcus, Prevotella, Ruminococcaceae, Faecalibacterium and Megasphaera also showed associations between saliva and gut. CONCLUSION: The optimal timing for examining and treating infant gut dysbiosis could be very early after birth. Together with the results from previous research, Ruminococcus and Veillonella deserve more investigation in the future to confirm their oral-to-gut transmission and potential effect in treating early-life intestinal dysbiosis.
Lai et al. (Fri,) studied this question.