Inclusion Criteria:  The patients who were diagnosed with persistent H. pylori infection and had previously failed one or more courses of eradication therapies that included amoxicillin, clarithromycin, or nitroimidazole.  Exclusion Criteria:  Age < 18 years old. The time frame was less than 6 months from the previous eradication therapy. The previous eradication therapy included furazolidone. Allergic to the medication. Pregnant or lactating women. Comorbidities of severe conditions like hepatic, renal or cardiorespiratory diseases or malignancy. Administration of antibiotics, bismuth or PPI in the preceding 4 weeks.