Efficacy of bismuth for antibiotic-resistant Helicobacter pylori strains eradication: A systematic review and meta-analysis.

Background & Aims: Antibiotic resistance of Helicobacter pylori (H. pylori) is increasing worldwide, and bismuth quadruple therapy has been recommended as a first-line regimen in many areas. This study aimed to investigate whether bismuth would improve the eradication rate (ER) of clarithromycin-/metronidazole-/levofloxacin-resistant H. pylori strains and how much additional efficacy bismuth could achieve.

Methods: PubMed, EMBASE, Web of Science, and Cochrane Central databases for randomized controlled trials were systematically searched by two independent reviewers until 15 January 2022. Pooled ERs of clarithromycin-/metronidazole-/levofloxacin-resistant H. pylori strains were compared between bismuth-containing and non-bismuth therapies. Pooled risk ratios (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model.

Results: Eight studies enrolling 340 individuals were included. The RRs of pooled ERs compared between bismuth-containing and non-bismuth therapies were 1.83 for clarithromycin-resistant strains (95% CI 1.16-2.89, pooled ER: 76.9% vs. 36.6%, p = .009, I  = 0%), 1.39 for metronidazole-resistant strains (95% CI 1.09-1.78, pooled ER: 86.8% vs. 60.9%, p = .008, I  = 37%), 2.75 for dual clarithromycin/metronidazole-resistant strains (95% CI 1.01-7.52, pooled ER: 76.9% vs. 18.2%, p = .05, I  = 0%), and 1.04 for levofloxacin-resistant strains (95% CI 0.56-1.93, pooled ER: 63.4% vs. 54.3%, p = .90; I  = 60%). Bismuth significantly increased the ERs of clarithromycin-, metronidazole-, and dual-resistant strains by 40%, 26%, and 59%, respectively. Subgroup analysis of treatment duration showed that the significantly higher eradication rate for antibiotic-resistant strains in bismuth-containing therapy than non-bismuth therapy was only observed in 14-day treatment regimens and not in 7-day regimens (p = .02 and .17, respectively).

Conclusions: Bismuth was most effective in improving the ERs of dual-resistant H. pylori strains, followed by clarithromycin- and metronidazole-resistant strains. Prolonged treatment duration might effectively improve the efficacy of bismuth in overcoming antibiotic resistance.