The Effect of Time Intervals for Rescue Treatment on Eradication Effect of Helicobacter Pylori Infection

Inclusion Criteria: * Patients aged 18-70. Patients with H.pylori infection (Positive for any of the following: 13C/14C-urea breath test, histopathology test, rapid urease test, stool H.pylori antigen test). Patients who have previously received helicobacter pylori eradication therapy and failed. Exclusion Criteria: * Patients with serious underlying diseases, such as liver insufficiency (Aspartate aminotransferase or alanine aminotransferase greater than 1.5 times the normal value), renal insufficiency (Cr≥2.0mg/dL or glomerular filtration rate \<50 ml/min), immunosuppression, malignant tumors, Coronary heart disease or coronary artery stenosis ≥75%. Patients who are pregnant or lactating or unwilling to take contraceptive measures during the trial. Patients with active gastrointestinal bleeding. Patients with a history of upper gastrointestinal surgery. Patients allergic to treatment drugs. Patients with medication history of bismuth agents, antibiotics, proton pump inhibitor and other drugs within 4 weeks Patients with other behaviors that may increase the risk of illness, such as alcohol and drug abuse Patients who are unwilling or incapable to provide informed consents.