Methods: This will be a multi-center, open labeled trial Patients: 360 patients with failure to H. pylori eradication for at least two times will be enrolled Determination of antibiotic resistance of H. pylori: Agar dilution test will be used to determine the minimum inhibitory concentrations of levofloxacin, tetracycline, rifabutin, and clarithromycin to guide the selection of antibiotics. Treatment regimens and assignment: Eligible patients will be randomized to receive either one of the treatments (A) Susceptibility testing guided therapy or (B) Empirical therapy Outcome Measurement: Primary End Point: Eradication rate will be evaluated according to Intent-to-treat (ITT) analyses. Secondary End Point: 1. Eradication rate according to per protocol analysis (PP analysis); 2. Frequency of adverse effects.