Twice daily standard dose of omeprazole achieves the necessary level of acid inhibition for Helicobacter pylori eradication. A randomised controlled trial using standard and double doses of omeprazole within a triple therapy

Background: Bacterial resistances to antibiotics is generally considered as the most important cause of H. pylori eradication failure. However, other factors such as the level of gastric acid inhibition could affect the outcome of eradicating regimens. Aim: To evaluate the impact of different degrees of acid inhibition on the efficacy of a triple eradication treatment for H. pylori infection. Secondly, to determine other predictors of unsuccessful eradication. Methods: 323 patients with H. pylori infection were treated with clarithromycin 500mg bid and Tinidazole 500 mg bid plus either omeprazole 20 mg bid or omeprazole 40 mg bid. Endoscopy with gastric biopsies and antimicrobial susceptibility testing were performed in all patients. Eradication was evaluated by means of urea-breath test at least 4 weeks after the therapy. Results: Eradication rates were (ITT and PP) 83.3% and 84.3% in patients receiving omeprazole 40 mg and 81.9% and 84.1% in those receiving omeprazole 80 mg (ns). Culture was successful in 218 patients (68.7%). Resistance to clarithromycin and to metronidazole were found in 30 (13.7%) and 45 patients (20.6%), respectively. Eighteen further patients (8.2%) harboured double-resistant strains. Resistance to antibiotics was comparable across the two treatment groups. In resistant patients the eradication rate was significantly lower than in patients harbouring antibiotic-sensitive strains (62/93, 66.6%, 95% CI 0.56-0.76, vs 107/125, 86%, 95% CI 0.78-0.91; p=0.001). Smoking (OR: 2.68) and antibiotic resistance (OR 2.73) were independent predictors of eradication failure. Oppositely, age, sex, alcohol intake, and omeprazole doses did not predict treatment failure. Conclusions: Omeprazole 20 mg bid achieves the optimal acid inhibition in H. pylori eradication. Increasing antisecretory activity above this level does not significantly enhance cure rates. Smoking and antibiotics-resistance are predictors of eradication failure