Abstract
BACKGROUND: Helicobacter pylori eradication therapy typically consists of a combination of antibiotics and an antisecretory drug. Probiotics may be added to reduce side effects and possibly improve outcomes. MATERIALS AND METHODS: We conducted a double-blind, randomized trial of pantoprazole plus either Lactobacillus reuteri (Gastrus) (high dose) or a matching placebo to assess the impact on the gut microbiota of H. pylori-positive adults. Fecal samples were collected at baseline and after one and 2 months for shotgun metagenomic sequencing. RESULTS: A total of 26 patients were recruited and completed therapy. L. reuteri was only detected in the group that received supplemental L. reuteri and only at the 1-month post-treatment interval. L. reuteri failed to colonize for long-term the gut, and challenge with L. reuteri failed to alter alpha-diversity (Shannon index) or beta-diversity (community ordination) metrics at any time point. Machine learning (PLS-DA) analysis identified the presence of L. reuteri as the most distinguishing feature at 1 month. No other taxa showed a significant difference between groups. CONCLUSION: Short-term administration of pantoprazole and L. reuteri had no lasting effects on gut microbial composition. While L. reuteri transiently bloomed during supplementation, the overall gut microbiota showed resilience, returning to baseline shortly after therapy. TRIAL REGISTRATION: Identifier: NCT03404440.