Whether non-bismuth quadruple therapy (concomitant therapy) is more effective than bismuth quadruple therapy or triple therapy for 14 days remains unknown.

Therefore, we aim to compare the eradication rates and long term re-infection rates of quadruple therapy for 10 days versus non-bismuth quadruple therapy for 10 days vs. triple therapy for 14 days.

Methods: This will be a multi-center, open labeled, randomized control trial Patients: H. pylori infected patients who have willingness to receive eradication therapy

Testing for H. pylori infection Before First Line Ttreatment

(1)Any two positive of rapid urease test, histology, serology and culture or a positive UBT will be considered as H. pylori infected

After First Line Treatment: C13-Urea breath test will be used to assess the existence of H. pylori 6-8 weeks after first line therapy.

Long term reinfection: C13- Urea breath test will be used to assess the recurrence of H. pylori 1 year after eradication therapy

First line therapy: open labeled, randomized control trial, randomized into one of the three groups Group (A): triple therapy for 14 days D1-D14: (lansoprazole 30mg + clarithromycin 500mg + amoxicillin 1gm) bid Group (B): non-bismuth quadruple therapy for 10 days D1-D10: lansoprazole 30mg bid + amoxicillin 1gm bid + clarithromycin 500mg bid + metronidazole 500mg bid Group (C): bismuth quadruple therapy for 10 days D1-D10: lansoprazole 30mg bid + colloidal bismuth subcitrate 300mg tid + metronidazole 500mg tid + tetracycline 500mg tid

Second line therapy: patients who fail from first line treatment will be rescue with the following treatment Group (A) Patient who fail from triple therapy will be retreated with bismuth quadruple therapy for 10 days D1-D10: lansoprazole 30mg bid + colloidal bismuth subcitrate 300mg tid + metronidazole 500mg tid + tetracycline 500mg tid Group (B) Patient who fail from non-bismuth quadruple therapy will be retreated with bismuth quadruple therapy for 10 days D1-D10: lansoprazole 30mg bid + colloidal bismuth subcitrate 300mg tid + metronidazole 500mg tid + tetracycline 500mg tid Group (C) Patients who fail from bismuth quadruple therapy will be retreated with non-bismuth quadruple therapy for 10 days D1-D10: lansoprazole 30mg bid + amoxicillin 1gm bid + clarithromycin 500mg bid + metronidazole 500mg bid

Inclusion Criteria:

Patients aged greater than 20 years who have H. pylori infection without prior eradication therapy and are willing to receive the sequential therapy will be eligible for enrolment. Written informed consents will be obtained from all patients prior to enrollment.

Exclusion Criteria:

Patients will be excluded from the study if any one of the following criteria is present: (1) children and teenagers aged less than 20 years, (2) history of gastrectomy, (3)gastric malignancy, including adenocarcinoma and lymphoma, (4) previous allergic reaction to antibiotics (amoxicillin, clarithromycin, metronidazole, or levofloxacin) and prompt pump inhibitors (lansoprazole), (5)contraindication to treatment drugs, (6) pregnant or lactating women, (7) severe concurrent diseases, and (8) Patients who cannot give informed consent by himself or herself.