The purpose of this study is to compare the effectiveness of three different antibiotic regimens against Helicobacter pylori (H. pylori).

Prevention of gastric cancer through eradication of H. pylori is one of the most promising strategies to reduce the global impact of cancer in the near term. Our long-term goal is to prevent gastric cancer by developing and validating an effective, simple, and low-cost approach to eradication of H. pylori. Our immediate goal, therefore, is to conduct a randomized study to compare the effectiveness of three different drug regimens for H. pylori infection. The three study arms are: Standard therapy - 14 day, 3-drug regimen of Lansoprazole, amoxicillin and clarithromycin (PACx14); Concomitant therapy - 5 day, 4-drug regimen of lansoprazole, amoxicillin, clarithromycin, metronidazole (PACMx5); Sequential therapy - 10 day, 4-drug regimen of lansoprazole, amoxicillin for 5 days, followed by lansoprazole, clarithromycin and metronidazole for 5 days (PAx5/PCMx5).

Inclusion Criteria:

• positive Urea Breath Test documenting H. pylori infection
• age 21 - 65 years
• no known allergies to study drugs
• only member of household participating in study
• no known medical conditions (other than H. pylori) that would preclude or require antibiotic therapy
• patients must be willing to discontinue alcohol use for 15 days (maximum duration of treatment plus one day)
• patients must be willing to discontinue use of antacids for duration of study treatment
• patients must not have used proton pump inhibitors (PPI) within 30 days of registration. Patients also must be willing to stop using non-study provided PPIs until the completion of the 6 week follow-up contact.
• patients must not have been treated with antibiotics for H. pylori in the past and must not have taken any other antibiotics within 30 days of registration.
• patients must be willing to return for 2 follow-up visits: 6 weeks after randomization following completion of treatment & 1 year after randomization
• patients must be willing to allow submission of blood for assays of serum markers of bacterial virulence and host genetic susceptibility and environmental factors and provide consent for use of specimens.

Exclusion Criteria:

• current use of anti-retroviral therapy for HIV or AIDS
• diagnosed congestive hear failure
• renal failure requiring dialysis
• diagnosed hepatic failure resulting in hyperbilirubinemia
• any current or prior malignancy except: adequately treated basal or squamous cell skin cancer, in situ cervical cancer, adequately treated Stage I or Stage II cancer from which the patient has been disease free for 5 years
• pregnancy or nursing mothers