1. Compare the efficacy of "Tetracycline combined with levofloxacin quadruple therapy", "standard tincture quadruple therapy" and "amoxicillin combined with levofloxacin quadruple therapy" on the second line of Helicobacter pylori sterilization.
2. To investigate the drug resistance of Helicobacter pylori and the host genotypes of CYP2C19 and IL-1B-511 on the sterilizing effect of three second-line Helicobacter pylori.

The "standard tincture quadruple therapy" and the "proton pump inhibitor combined with fluoroquinolone and amoxicillin triple therapy" recommended by the 5th Mazdock-Florence Consensus Conference on the second line of Helicobacter pylori treatment The sterilization rate is not ideal (less than 80%). Recently, we have developed a "Tetracycline combined with levofloxacin quadruple therapy" for first-line treatment failure of H. pylori infection, with a relatively high sterilization rate (> 95%). A randomized controlled trial confirmed that the elimination rate of "Tetracycline combined with levofloxacin quadruple therapy" was better than "proton pump inhibitor combined with fluoroquinolone" after "standard triple therapy" and "non-tank tetratherapy" sterilization failure. Triple therapy with amoxicillin.

Inclusion Criteria:

1. at least 20 years old
2. subject was failure for the first line therapy of Helicobacter pylori

Exclusion Criteria:

1. Those who are allergic to the drugs used in this study
2. Those who have had a stomach surgery
3. Those who have antibiotics within four weeks of treatment
4. Those who have severe cirrhosis, uremia or malignancy
5. Those who are a pregnant woman or a woman who breastfeeds