The proposed study will test the hypothesis that H. pylori can be eradicated successfully (>85%) using half-or full-dose "concomitant" non-bismuth quadruple therapy regimen: rabeprazole, amoxicillin, clarithromycin and metronidazole twice daily for 7 days in patients with peptic ulcers and H. pylori related gastritis.

Two hundred patients from the outpatient department and the endoscopy unit at AUBMC will be enrolled in this open-label trial. Patients with positive CLO tests or urea breath tests, documenting H.pylori infection, will be randomized into one of two groups: Full dose or half dose the concomitant regimen, with 100 patients in each group. Compliance and side effects will be assessed, and a urea breath test will be done for all patients after 4 weeks of therapy completion to evaluate eradication rates. Success of therapy will be evaluated according to intent-to treat and per-protocol analyses.

Infection with H. pylori has been linked with chronic active gastritis, peptic ulcer disease, adenocarcinoma and Non-Hodgkin's lymphoma of the stomach. Eradication of this organism has been recommended for patients with peptic ulcer disease, low-grade gastric mucosa-associated lymphoid tissue lymphoma, atrophic gastritis, unexplained iron deficiency anemia, chronic idiopathic thrombocytopenic purpura, as well as first-degree relatives of gastric cancer patients.

Guidelines still recommend using triple therapy regimen of PPI, clarithromycin and amoxicillin/metronidazole twice daily for 7 to 14 days. Over the years, it has become clear that the first-line triple therapy is loosing efficacy worldwide with PP and ITT eradication rates inferior to 80%. Antimicrobial resistance plays an important role in some of these failures.

Major H. pylori study groups in the world have agreed that alternative treatment regimens are urgently needed. So far, 2 alternative treatment regimens have shown superiority over the first-line treatment protocols: the sequential therapy consisting of a combination of amoxicillin and a PPI twice a day for 5 days followed by another 5 days of the PPI plus clarithromycin and tinidazole/metronidazole, and the concomitant non-bismuth quadruple regimen consisting of PPI, clarithromycin, metronidazole, and amoxicillin twice daily.

The proposed study will test the hypothesis that H. pylori can be eradicated successfully (>85%) using half-or full-dose "concomitant" non-bismuth quadruple therapy regimen: rabeprazole, amoxicillin, clarithromycin and metronidazole twice daily for 7 days in patients with peptic ulcers and H. pylori related gastritis.

Two hundred patients from the outpatient department and the endoscopy unit at AUBMC will be enrolled in this open-label trial. Patients with positive CLO tests or urea breath tests, documenting H.pylori infection, will be randomized into one of two groups: Full dose or half dose the concomitant regimen, with 100 patients in each group. Compliance and side effects will be assessed, and a urea breath test will be done for all patients after 4 weeks of therapy completion to evaluate eradication rates. Success of therapy will be evaluated according to intent-to treat and per-protocol analyses.

Inclusion Criteria:

• documented H.pylori infection by a CLO test or a Urea Breath Test
• sign the informed consent

Exclusion Criteria:

• Age under 18 or older than 80 years
• Allergies to any of the drugs used
• Recent antibiotic therapy (within 2 weeks of enrolment)
• Severe ulcers or bleeding
• Gastric perforation or obstruction
• Previous gastrectomy
• Gastric cancer
• Pregnancy or lactation
• Prior eradication therapy for H. pylori
• Severe concomitant disease or condition making the treatment unlikely to be effective i.e. alcoholism, drug addiction, and history of poor compliance.