Inclusion Criteria:  Patients aged 18-70 with H. pylori infection. Patients with previous Helicobacter pylori eradication.  Exclusion Criteria:  Patients treated with H2-receptor antagonist, PPI, bismuth and antibioticsin 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 couldinterfere with the examination or therapeutic protocol.