Inclusion Criteria:  Patients aged 18-70 with H. pylori infection. Patients with previous Helicobacter pylori eradication. Patients Allergic to Penicillin.  Exclusion Criteria:  Patients treated with H2-receptor antagonist, PPI, bismuth and antibiotics in the previous 4 weeks. Patients with gastrectomy, acute GI bleeding and advanced gastric cancer. Patients with known or suspected allergy to study medications. Currently pregnant or lactating. Inability to provide informed consent and other situations that could interfere with the examination or therapeutic protocol.