Characterization of the unique oral microbiome of children harboring Helicobacter pylori in the oral cavity

Abstract

Objective: Helicobacter pylori infection is acquired in childhood via the oral cavity, although its relationship with the characteristics of the oral microbiome has not been elucidated. In this study, we performed comprehensive analysis of the oral microbiome in children and adults with or without H. pylori in the oral cavity.

Methods: Bacterial DNA was extracted from 41 adult and 21 child saliva specimens, and H. pylori was detected using PCR. 16S rRNA gene amplification was performed for next-generation sequencing. Bioinformatic analyses were conducted using Quantitative Insights into Microbial Ecology 2 (QIIME 2).

Results: Faith's phylogenetic diversity analysis showed a significant difference between H. pylori-negative adult and child specimens in terms of α-diversity (p < 0.05), while no significant difference was observed between H. pylori-positive adult and child specimens. There was also a significant difference in β-diversity between H. pylori-positive and negative child specimens (p < 0.05). Taxonomic analysis at the genus level revealed that Porphyromonas was the only bacterium that was significantly more abundant in both H. pylori-positive adults and children than in corresponding negative specimens (p < 0.01 and p < 0.05, respectively).

Conclusion: These results suggest unique oral microbiome characteristics in children with H. pylori infection in the oral cavity.

Keywords: Helicobacter pylori; metagenomic analysis; oral cavity; oral microbiome; saliva.

Figure 1.

Faith’s phylogenetic diversity analysis of α-diversity. (a) Comparison between adults and children in all specimens. Comparisons between (b) H. pylori-positive and -negative specimens from adults, and (c) H. pylori-positive and -negative specimens from children. Comparisons between (d) H. pylori-positive adults and children, and (e) H. pylori-negative adults and children. Whiskers indicate maximum and minimum values, while boxes indicate interquartile ranges. *P<0.05 and **P<0.01 by Mann–Whitney U test.

Figure 2.

PERMANOVA of β-diversity in H. pylori-positive and -negative groups of adults and children. (a) Comparison between adult H. pylori-negative specimens and child H. pylori-positive/-negative specimens. (b) Comparison between adult H. pylori-positive specimens and child H. pylori-positive/-negative specimens. (c) Comparison between child H. pylori-positive and -negative specimens. The contribution rate of each axis (1–3) in the principal coordinate analysis (PCoA) is shown in parentheses. *p < 0.05 by PERMANOVA of the weighted UniFrac distance.

Figure 3.

Taxonomic analysis at the phylum level in H. pylori-positive and H. pylori-negative specimens. (a) Children. (b) Adults. Whiskers indicate maximum and minimum values, while boxes indicate interquartile ranges. *p < 0.05 and **p < 0.01 by Mann–Whitney U test.

Figure 4.

Taxonomic analysis at the genus level in H. pylori-positive and H. pylori-negative specimens. (a) Children. (b) Adults. *p < 0.05 and **p < 0.01 by Mann–Whitney U test.