[Intestinal and pharyngeal microbiota in early neonates: an analysis based on high-throughput sequencing].

Objectives: To investigate the distribution characteristics and correlation of intestinal and pharyngeal microbiota in early neonates.

Methods: Full-term healthy neonates who were born in Shanghai Pudong New Area Maternal and Child Health Hospital from September 2021 to January 2022 and were given mixed feeding were enrolled. The 16S rRNA sequencing technique was used to analyze the stool and pharyngeal swab samples collected on the day of birth and days 5-7 after birth, and the composition and function of intestinal and pharyngeal microbiota were analyzed and compared.

Results: The diversity analysis showed that the diversity of pharyngeal microbiota was higher than that of intestinal microbiota in early neonates, but the difference was not statistically significant (>0.05). On the day of birth, the relative abundance of in the intestine was significantly higher than that in the pharynx (<0.05). On days 5-7 after birth, the relative abundance of and in the intestine was significantly higher than that in the pharynx (<0.05), and the relative abundance of in the intestine was significantly lower than that in the pharynx (<0.05). At the genus level, there was no significant difference in the composition of dominant bacteria between the intestine and the pharynx on the day of birth (>0.05), while on days 5-7 after birth, there were significant differences in the symbiotic bacteria of , , , , and - between the intestine and the pharynx (<0.05). The analysis based on the database of Clusters of Orthologous Groups of proteins showed that pharyngeal microbiota was more concentrated on chromatin structure and dynamics and cytoskeleton, while intestinal microbiota was more abundant in RNA processing and modification, energy production and conversion, amino acid transport and metabolism, carbohydrate transport and metabolism, coenzyme transport and metabolism, and others (<0.05). The Kyoto Encyclopedia of Genes and Genomes analysis showed that compared with pharyngeal microbiota, intestinal microbiota was more predictive of cell motility, cellular processes and signal transduction, endocrine system, excretory system, immune system, metabolic diseases, nervous system, and transcription parameters (<0.05).

Conclusions: The composition and diversity of intestinal and pharyngeal microbiota of neonates are not significantly different at birth. The microbiota of these two ecological niches begin to differentiate and gradually exhibit distinct functions over time.