Current guidelines have recommended classical bismuth-containing quadruple therapy including proton-pump inhibitor, bismuth, tetracycline, metronidazole as the empirical rescue therapy. However, tetracycline is clinically unavailable in China and the high frequency of adverse events of bismuth quadruple therapy often result in poor compliance, which limited the applicability of this recommendation. This study aimed to compare the efficacy and tolerability of a 14-day bismuth-containing quadruple rescue therapy in which tetracycline was replaced by doxycycline.

Inclusion Criteria:

• Ability and willingness to participate in the study and to sign and give informed consent
• Confirmed H. pylori infection and with previous treatment failure

Exclusion Criteria:

• subjects naive to H. pylori treatment,
• under 18 or over 80 years old
• history of gastrectomy
• pregnant or lactating women
• severe systemic diseases or malignancy
• administration of antibiotics, bismuth, antisecretory drugs, or Chinese herb medicine in the preceding 8 weeks