BACKGROUND Bismuth-containing quadruple therapy is widely used as second-line treatment for Helicobacter pylori infection. This prospective study investigated the changes in the annual H. pylori eradication rates of quadruple therapy.

METHODS This study included an intention-to-treat (ITT) population of 452 subjects who failed first-line eradication therapy for H. pylori between 2003 and 2018. All subjects received a 14-day course of bismuth-containing quadruple therapy consisting of esomeprazole (40 mg twice daily), metronidazole (500 mg thrice daily), bismuth subcitrate (120 mg four times daily), and tetracycline (500 mg four times daily). Per-protocol (PP) analysis of data was performed in subjects who followed up with strict treatment adherence. Eradication was confirmed based on the results of the ¹³ C-urea breath test, rapid urease test (CLOtest^® ), and histopathologic evaluation. Compliance and adverse effects were also investigated. A minimal inhibitory concentration test was performed on tissue samples obtained from 103 subjects.

RESULTS The overall eradication rates following ITT and PP analyses were 78.8% (356/452) and 89.5% (314/351), respectively. The annual eradication success rate did not show significant changes (P = .062 [ITT], P = .857 [PP]) over the 15-year study period. Adverse events were reported in 57.3% of the ITT population. The rates of resistance to metronidazole and tetracycline were 44.7% and 18.4%, respectively.

CONCLUSIONS Despite high antibiotic resistance rates, no significant reduction in annual eradication rates was observed during the study period.