A 60-year-old man with recurrent peptic ulcer disease tests positive for H. pylori by urea breath test. He previously received clarithromycin-based triple therapy without eradication. Which second-line regimen is most appropriate?

• A Bismuth quadruple therapy (PPI + bismuth + metronidazole + tetracycline) ✓
• B Repeat clarithromycin triple therapy for 14 days
• C Dual therapy with high-dose PPI + amoxicillin
• D Sequential therapy (amoxicillin 5 days then clarithromycin + metronidazole 5 days)

Explanation

After failure of clarithromycin-based triple therapy, bismuth quadruple therapy (PPI + bismuth subcitrate + metronidazole + tetracycline for 10–14 days) is the recommended second-line regimen per Maastricht VI/Florence 2022 consensus, as it avoids re-using clarithromycin and is effective even with metronidazole resistance. The eradication rate with bismuth quadruple therapy as salvage exceeds 85%. Repeating clarithromycin-based therapy is inappropriate due to acquired resistance.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.