The purpose of this study is to evaluate efficacy of a 14-day concomitant therapy for the third-line treatment of Helicobacter pylori infection, and whether it is safe while maintaining an ideal eradication rates.

Helicobacter pylori infects half of the world's population. H.pylori eradication is an effective approach to reduce the risk of developing gastric cancer. However, eradication rates of first-line therapy decreased over years due to the rapidly increasing antibiotic resistance of H. pylori worldwide. An ideal rescue therapeutic regimen to cure refractory H.pylori infection is currently warranted.

Few published paper evaluated the efficacy of 14-day furazolidone containing concomitant therapy in the third line treatment. This study aims to propose a new concomitant therapy for the patients with two or more treatment failure, and then evaluates whether adverse effects are tolerable. .

Inclusion Criteria:

• Patients aged 18-70 with persistent H. pylori infection.
• Patients failed at least three different standard eradication therapies before. Previous standard eradication therapy was defined as a 10-day or 14-day quadruple regimen designed according to Maastricht V report.

Exclusion Criteria:

• Patients unable or unwilling to receive gastroscopy.
• Patients treated with H2-receptor antagonist, PPI, bismuth and antibiotics in the previous 4 weeks.
• Patients with gastorectomy, acute GI bleeding and advanced gastric cancer.
• History of allergy to any of the drugs used in the study.
• Severe concomitant cardiovascular, respiratory, or endocrine diseases,clinically significant renal or hepatic disease, hematologic disorders and any other clinically significant medical condition that could increase risk.
• Currently pregnant or lactating.
• Severe neurologic or psychiatric disorders.
• Alcohol abuse or drug addiction.
• Patients with compliance lower than 90% in any previous treatment are not included.
• Inability to provide informed consent and other situations that could interfere with the examination or therapeutic protocol.