Efficacy of a 14-day quadruple-therapy regimen for third-line Helicobacter pylori eradication Hsiang Tso Huang,1 Hsin-Ming Wang,1 Shih-Cheng Yang,1 Wei-Chen Tai,1 Chih-Ming Liang,1 Keng-Liang Wu,1 Chen-Hsiang Lee,2 Seng-Kee Chuah1 1Division of Hepato-Gastroenterology, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Niao-Song District, Kaohsiung 833, Taiwan; 2Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Niao-Song District, Kaohsiung 833, Taiwan Purpose: To assess the efficacy of amoxicillin, tetracycline, high-dose metronidazole, and a proton-pump inhibitor for third-line Helicobacter pylori eradication. Methods: We enrolled 70 consecutive patients who had registered, failed to respond to two rounds of H. pylori eradication, and undergone endoscopy for H. pylori culture. Seven patients were lost to follow-up. Patients were treated according to the results of antibiotic-susceptibility testing reports (cultured group,