***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND & AIMS The role of omeprazole in triple therapy and the impact of Helicobacter pylori resistance on treatment outcome are not established . This study investigated the role of omeprazole and influence of primary H. pylori resistance on eradication and development of secondary resistance . METHODS Patients ( n = 539 ) with a history of duodenal ulcer and a positive H. pylori screening test result were r and omized into 4 groups . OAC group received 20 mg omeprazole , 1000 mg amoxicillin , and 500 mg clarithromycin ; OMC group received 20 mg omeprazole , 400 mg metronidazole , and 250 mg clarithromycin ; and AC ( amoxicillin , 1000 mg , and clarithromycin , 500 mg ) and MC ( metronidazole , 400 mg , and clarithromycin , 250 mg ) groups received no omeprazole . All doses were administered twice daily for 1 week . H. pylori status was assessed before and after therapy by 13C-urea breath test . Susceptibility testing was performed at entry and in patients with persistent infection after therapy . RESULTS Eradication ( intention to treat [ n = 514]/per protocol [ n = 449 ] ) was 94%/95 % for OAC , 26%/25 % for AC ( P < 0.001 ) , 87%/91 % for OMC , and 69%/72 % for MC ( P < 0.001 ) . Primary resistance was 27 % for metronidazole , 3 % for clarithromycin , and 0 % for amoxicillin . Eradication in primary metronidazole-susceptible/-resistant strains was 95%/76 % for OMC and 86%/43 % for MC . Secondary metronidazole and clarithromycin resistance each developed in 12 patients : 8 treated with omeprazole and 16 without omeprazole . CONCLUSIONS Addition of omeprazole achieves high eradication rates , reduces the impact of primary resistance , and may decrease the risk of secondary resistance compared with regimens containing only two antibiotics S‐mephenytoin 4’‐hydroxylase ( CYP2C19 ) catalyses the metabolism of rabeprazole to some extent . Based on the metabolic and pharmacokinetic differences among other proton pump inhibitors such as omeprazole , lansoprazole and pantoprazole , rabeprazole appears to be the least affected proton pump inhibitor by the CYP2C19‐related genetic polymorphism Objective Helicobacter pylori treatment failure is thought to be due mainly to polymorphic cytochrome P450 2C19 ( CYP2C19 ) genetic polymorphism , associated with proton pump inhibitor metabolism , and antimicrobial susceptibility . This report has ascertained which was more important , CYP2C19 polymorphism or antimicrobial susceptibility , when using 1-week lansoprazole-based or rabeprazole-based triple therapy in Japan . Design An open , r and omized , parallel group study . Setting One hundred and forty-five subjects with H. pylori-positive gastritis or peptic ulcers were r and omly assigned to receive 30 mg lansoprazole twice daily ( LAC group ) , 10 mg rabeprazole twice daily ( RAC20 group ) , or 20 mg rabeprazole twice daily ( RAC40 group ) , with 1000 mg amoxicillin twice daily and 400 mg clarithromycin twice daily for 1 week . Antimicrobial resistance testing was performed by E-test . More than 4 weeks after completion of treatment , H. pylori status was assessed by 13C-urea breath test , histology , and culture . Results Cure rates expressed as intention-to-treat and per- protocol analyses , respectively , were 79.6 and 83.0 % with LAC , 85.4 and 89.1 % with RAC20 , and 83.3 and 88.9 % with RAC40 . In the case of clarithromycin-sensitive strains , the cure rates were more than 97 % , regardless of CYP2C19 polymorphism . However , treatment succeeded in only one out of 16 clarithromycin-resistant strains . Conclusions The key to successful eradication of H. pylori , using lansoprazole or rabeprazole with clarithromycin and amoxicillin , is clarithromycin susceptibility , not CYP2C19 polymorphism Aim : To investigate the effect of different proton pump inhibitors , S‐mephenytoin 4′‐hydroxylase ( CYP2C19 ) genotype and antibiotic susceptibility on the eradication rate of Helicobacter pylori 
    Output:
    
The systematic review published in this issue suggests that particularly for omeprazole in combination with amoxicillin or amoxicillin and clarithromycin the success rate is much lower when compared to other proton pump inhibitors ( PPIs ) .