Clinical Study of Correlation for the Intestinal and Pharyngeal Microbiota in the Premature Neonates

Abstract

Objective: There are mutual influences between intestine and lung, that propose a concept of the gut-lung axis, but the mechanism is still unclear. Microbial colonization in early life plays an important role in regulating intestinal and lung function. In order to explore the characteristics of early microbiota on the gut-lung axis, we studied the correlation between intestinal and pharyngeal microbiota on day 1 and day 28 after birth in premature neonates. Methods: Thirteen neonates born at 26-32 weeks gestational age (GA) hospitalized at the neonatal intensive care unit (NICU) of the West China Second Hospital of Sichuan University were enrolled in this study. Stool samples and pharyngeal swabs samples were collected from each neonate on the first day (T1) and the 28th day (T28) after birth. Total bacterial DNA was extracted and sequenced using the Illumina MiSeq Sequencing System based on the V3-V4 hyper-variable regions of the 16S rRNA gene. Based on the sequencing results, the composition of the intestinal and pharyngeal microbiota was compared and analyzed. Results: At T1, the difference in microbial composition between intestine and pharynx was not statistically significant. The intestinal microbiota was mainly composed of Unidentified Enterobacteriaceae, Ralstonia, Streptococcus, Fusobacterium, Ureaplasma, etc. The pharyngeal microbiota was mainly composed of Ureaplasma, Bacteroides, Fusobacterium, etc. Ureaplasma and Fusobacterium were detected in both intestine and pharynx. At T28, there was a significant difference in microbial composition between intestine and pharynx (p < 0.001). The intestinal microbiota was mainly composed of Unidentified Clostridiales, Klebsiella, Unidentified Enterobacteriaceae, Enterobacter, Streptococcus, etc. Pharyngeal microbiota was mainly composed of Streptococcus, Rothia, etc. Streptococcus was detected in both intestine and pharynx. Conclusions: The intestine and pharynx of premature neonates have a unique microbial composition, and share some common microbiota. Whether these microbiotas play a role in the mechanism of gut-lung crosstalk needs further study.

Keywords: 16S rRNA sequencing; gut-lung axis; intestinal micriobiota; pharyngeal microbiota; preterm neonate.

Figure 1

Comparisons between intestinal and pharyngeal microbiota. (A) OTUs were shared by the intestine and pharynx. (B) Comparison of the microbial biodiversity between intestine and pharynx, the shannon index, and chao1 were shown as estimators. (C) PCoA plot based on OTU abundance. Each point represents the intestinal or pharyngeal microbiota of a subject. (D) Histogram of the LDA scored for differentially abundant genera between intestine and pharynx. LDA scores were calculated by LDA effect size using linear discriminant analysis.

Figure 2

The composition of intestinal and pharyngeal microbiota.at the genus level. (A) The microbial composition of each sample. (B) Average microbiota of T1s, T1y, T28s, and T28y (T1s: meconium samples at T1; T1y: pharyngeal swabs samples at T1; T28s: stool samples at T28; T28y: pharyngeal swabs samples at T28).