Medications will be adjusted according to clarithromycin，metronidazole and levofloxacin sensitivity. All drugs will be prescribed for 14 days.(1) When three of them or clarithromycin and metronidazole are sensitive, esomeprazole 20mg bid, clarithromycin 0.5g bid and metronidazole 0.4g bid will be prescribed. (2) When two of them (levofloxacin and clarithromycin or metronidazole) are sensitive, esomeprazole 20mg bid, levofloxacin 0.5g qd plus clarithromycin 0.5g bid or metronidazole 0.4g bid will be prescribed. (3) When one of them (clarithromycin or levofloxacin) is sensitive, esomeprazole 20mg bid, bismuth Potassium Citrate 600mg bid, metronidazole 0.4g qid plus clarithromycin 0.5g bid or levofloxacin 0.5g qd will be prescribed.(4) When only metronidazole or none of them is sensitive, esomeprazole 20mg bid, bismuth Potassium Citrate 600mg bid, metronidazole 0.4g qid plus tetracycline 0.4g qid will be prescribed.

Proton pump inhibitor

Six weeks after completion of therapy, H. pylori eradication was assessed by ¹³C-urea breath test. Eradication was defined as negative result from urea breath test (<4‰) (4‰ as the cutoff value).

The subjects were asked to grade the severity of adverse events according to their influence on daily activities, experienced as "mild" (transient and well tolerated), "moderate" (causing discomfort and partially interfering with daily activities), or "severe" (causing considerable interference with daily activities)