Helicobacter pylori eradication with bismuth quadruple therapy leads to dysbiosis of gut microbiota with an increased relative abundance of Proteobacteria and decreased relative abundances of Bacteroidetes and Actinobacteria

Abstract Background Bismuth quadruple therapy is the treatment of choice for the first‐line therapy of Helicobacter pylori infection in areas of high clarithromycin resistance. Currently, the impact of the promising treatment on gut microbiota remains unclear. Aim To investigate the short‐term and long‐term impacts of bismuth quadruple therapy on gut microbiota. Methods Adult patients with H. pylori ‐related gastritis were treated with 14‐day bismuth quadruple therapy. Fecal samples were collected before treatment at week 2, week 8, and week 48. Nucleic acid extraction from fecal samples was performed. The V3‐V4 region of the bacterial 16S rRNA gene was amplified by polymerase chain reaction and sequenced with the MiSeq followed by data analysis using Qiime pipeline. Results Eleven patients received complete follow‐up. Before treatment, the most abundant phyla were Firmicutes (45.3%), Bacteroidetes (24.3%), Proteobacteria (9.9%), and Actinobacteria (5.0%). At the end of bismuth therapy, the relative abundances of Bacteroidetes and Actinobacteria decreased to 0.5% ( P < .001) and 1.3% ( P = .038), respectively. Additionally, the relative abundance of Verrucomicrobia also decreased from 3.2% to 1.11E−3% ( P = .034). In contrast, the relative abundances of Proteobacteria and Cyanobacteria increased ( P < .001 and P = .003, respectively). At week 8, the relative abundances of all phyla restored to the levels at baseline. The relative abundances of all phyla at week 48 also did not significantly differ from those at baseline. During eradication therapy, 6 patients (55%) reported at least 1 adverse event. The relative abundance of phylum Proteobacteria in patients with adverse effects was more than that in patients without adverse effects (68.7% ± 8.8% vs 43.4% ± 25.5%; P = .048). Conclusions Bismuth quadruple therapy for H. pylori eradication can lead to short‐term dysbiosis of gut microbiota. The increase in Proteobacteria in gut microbiota may attribute to the development of adverse effects during bismuth quadruple therapy.