The patients who accepted the quadruple eradication program of the helicobacter pylori but failed to eradicate helicobacter pylori will be assessed the most suitable re-eradication time of helicobacter pylori.

Helicobacter pylori (HP) infection is a common global infectious disease, which is an important cause of chronic gastritis, peptic ulcer and gastric cancer. At present, due to the non-standard Helicobacter pylori eradication program in clinical work, poor patient compliance and other reasons, the phenomenon of HP eradication treatment failure is more and more common. However, there is still no conclusion on the most appropriate time for remedial treatment inpatients with Hp eradication failure.

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.

The patients in Shandong province,aged between 18 and 70 years old, with positive H. pylori infection that was eradicated by previous therapies but failed are included.