The aim of this randomized trial is to compare the efficacy and tolerability of H. pylori eradication with a 5-day quadruple therapy versus a clarithromycin-containing triple therapy.

Eligible patients with H pylori infection were randomized to receive either five-day QUAD (esomeprazole 20mg b.d., bismuth subcitrate 120mg q.i.d., tetracycline 250mg q.i.d. and metronidazole 250mg q.i.d.) or EAC (esomeprazole 20mg b.d., amoxicillin 1g b.d. and clarithromycin 500mg b.d.). H. pylori status was rechecked by 13C urea breath test 8 weeks after treatment. Patients who failed their respective therapy were invited to undergo H. pylori susceptibility testing and crossover to receive the alternative regimen for the same duration.

Inclusion Criteria:

• patients with H. pylori infection
• did not receive H. pylori eradication therapy before

Exclusion Criteria:

• patients who have received previous H. pylori eradication therapy
• co-morbidity of liver cirrhosis
• co-morbidity of renal failure
• co-morbidity of alcoholism
• co-morbidity of malignancy
• received antibiotics, bismuth preparations, proton pump inhibitors or probiotic in the preceding three months
• patients with known allergy to the medications used
• patients with a history of previous gastrointestinal diseases or gastric surgery
• pregnancy