The eradication of Helicobacter pylori restores rather than disturbs the gastrointestinal microbiota in asymptomatic young adults.

Background: The eradication of Helicobacter pylori (H pylori) has been suggested to reduce the risk of gastric cancer, but its impact on the gut microbiota has attracted public attention. This study aimed to investigate the short-term and long-term effects of bismuth quadruple therapy on both gastric and fecal microbiota.
Methods: Ten asymptomatic young adults with H pylori-related gastritis were treated with bismuth quadruple therapy for 14 days, and 7 age-matched adults without H pylori infection were enrolled as healthy controls. Both fecal and gastric mucosa samples were collected from H pylori-positive patients at weeks 0, 6, and 26, while fecal samples were collected from healthy controls. The gastric and gut microbiota were analyzed by 16S rRNA gene sequencing.
Results: The structure of the gastric microbiota was significantly changed after the eradication of H pylori with increased alpha diversity over time. The relative abundance of H pylori sharply decreased from more than 70% to nearly 0% after treatment, while some beneficial bacteria, such as Lactobacillus and Bifidobacterium, were increased. The microbial diversity of gut microbiota was higher in H pylori-infected patients than in healthy controls, which tended to decrease after eradication. The potentially beneficial gut bacteria Blautia and Lachnoclostridium were enriched at week 26 compared to week 0, while the pathogenic Alistipes were depleted to a level close to that of the healthy controls.
Conclusions: Bismuth quadruple therapy for H pylori eradication can restore the diversity of gastric microbiota with enrichment of beneficial bacteria. The composition of gut microbiota after H pylori eradication trends toward healthy status instead of becoming dysbiotic.
(© 2019 John Wiley & Sons Ltd.)