The researchers collect patients who accepted eradication program of the helicobacter pylori but failed to eradicate helicobacter pylor from the outpatient clinic. After rescue therapy, evaluating the effect of retreatment interval on eradication effect of Helicobacter pylori infection.

The researchers collect patients who accepted eradication program of the helicobacter pylori but failed to eradicate helicobacter pylor from the outpatient clinic. Record the interval between the last eradication therapy and this time，6-8 weeks after treatment, the subjects will re-take the 13C-urea breath test. Calculating the eradication rates, adverse reaction rates, patient compliance of each group. Evaluating the effect of retreatment interval 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.

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.