eradication of helicobacter pylori ( h. pylori ) infection has been reported as an effective strategy in the treatment of peptic ulcers and gastric mucosa - associated lymphoid tissue lymphoma , in addition to the prevention of recurrence of gastric cancer after endoscopic resection . the first - line regimen for the treatment of h. pylori infection in japan is triple therapy with a proton pump inhibitor ( ppi ) , amoxicillin ( amx ) , and clarithromycin ( clr ) , administered for 7 days . failure of this first - line therapy against h. pylori infection has been reported in approximately 20% of infected patients . at the 2008 meeting of the japanese society for helicobacter research , the mean national clr resistance rates from 2002 to 2006 were reported to be 18.9 , 21.2 , 27.7 , 29.0 , and 27.2% . the mean nationwide clr resistance rate determined by the japanese society of chemotherapy was 7.0% ( 21/302 ) in 2000 , indicating an increase of resistance by approximately 20% over several years . furthermore , it appears that the prevalence of clr - resistant h. pylori is increasing rapidly , and therefore , a resultant decrease in eradication achieved by the therapy , currently available under the national health insurance scheme , is a concern . failure of therapy with ppi - amx - metronidazole ( mnz ) , administered for 1 week as a second - line regimen after failure of the first - line regimen , has been reported in approximately 10% of infected patients . although the prevalence of h. pylori resistant to mnz has been reported to be 880% in different countries , that in japan has been reported to be 512% . these findings suggest that the first - line therapy with ppi - amx - mnz may be recommended in japan . the aim of our retrospective study was to compare the efficacy and tolerability of the 7-day first - line h. pylori eradication regimen composed of ppi , clr , and amx , with those of a regimen composed of ppi , mnz , and amx . data of patients , who were administered first - line h. pylori eradication therapy at the tokyo medical center between april 2008 and november 2011 , were reviewed . patients who had received a previous eradication therapy and had known peptic ulcer diseases and had used nonsteroidal anti - inflammatory drug , aspirin or clopidogrel were excluded from the study . endoscopic examinations were conducted before treatment for all the patients , and h. pylori positivity was confirmed by the results of the c - urea breath test or the presence of h. pylori - specific igg antibodies in the serum . the 7-day triple regimen composed of lansoprazole ( 30  mg , b.d . ) , clr ( 400  mg , b.d . ) , and amx ( 750  mg , b.d . ) was administered to 55 patients , and that composed of omeprazole ( 20  mg , b.d . ) , mnz ( 250  mg , b.d . ) , and amx ( 750  mg , b.d . ) was administered to 55 patients . if the day of the week of patient s first visit was tuesday , wednesday , or thursday , the regimen composed of lansoprazole , clr , and amx was chosen . if the day of the week of patient s first visit was monday or friday , the regimen composed of omeprazole , mnz , and amx was chosen . eradication was confirmed by the results of the c - urea breath test at 12 weeks after completion of the therapy . the c - urea used was 100  mg c - labelled urea produced by otsuka pharmaceutical co. ltd . the study was approved by the ethics committee of national hospital organization tokyo medical center , and informed consent was given by all the patients prior to the treatments . statistical analyses were performed using the chi - square , fisher s exact , and student s t tests , as appropriate . statistical analyses were performed using the chi - square , fisher s exact , and student s t tests , as appropriate . one hundred ten patients were enrolled ; of these 6 patients dropped out of the study . the combination of lansoprazole , clr , and amx resulted in eradication rates of 74.5% ( intention - to - treat ; itt ) and 80.4% ( per protocol ; pp ) . the combination of omeprazole , mnz , and amx resulted in eradication rates of 96.4% ( itt ) and 100% ( pp ) . the regimen composed of omeprazole , mnz , and amx was significantly more effective than that composed of lansoprazole , clr , and amx ( p<0.05 for itt , p<0.01 for pp , table  1 ) . adverse events were observed in 7 of 51 patients ( 13.7% ) in the ppi  +  clr  +  amx group and 6 of 53 patients ( 11.3% ) in the ppi  +  mnz  +  amx group . in all the cases , the side effects were mild and mainly included mild diarrhea , taste disturbance , or stomatitis . one week of triple therapy using a ppi combined with amx and clr is recommended as the first - line treatment choice for the eradication of h. pylori in japan . the resistance to clr is easily acquired and widespread prescription of clr over the years lead to the spread of resistance of h. pylori to clr . sasaki et al . reported the eradication rates of first - line eradication therapy with clr from 1995 to 2008 ( divided into four terms ; 19972000 , 20012003 , 20042006 , 20072008 ) , and the eradication rate decreased significantly from 90.6 to 80.2% , 76.0 , and 74.8% . the study demonstrated the evident decline in eradication rates for the triple therapy using a ppi , amx , and clr in japan . the present study showed an excellent eradication rate of 96.4% ( itt ) and 100% ( pp ) with a 7-day regimen of mnz , amx , and ppi as the first - line treatment . this regimen composed of ppi , mnz , and amx was significantly more effective than that composed of ppi , clr , and amx , without differences in tolerability . the first - line regimen with clr should be changed into another regimen such as the regimen with mnz in order to improve the eradication rate , because recent prevalence of clr resistance is estimated as more than 30% in japan . the resistance rates to amx ( mic0.06  g / ml ) in groups with no history of eradication treatment , a history of 1 treatment failure , and a history of 2 treatment failures were 13.6 , 26.5 , and 49.5% , respectively . the mic90 of amx increased by 2-fold after every eradication failure , and accumulation of pbp1 mutations were associated with a gradual increase in the resistance to amx . these results suggest that the first - line therapy with less chances of failure should be recommended to prevent further spread of amx - resistant h. pylori strains . although lansoprazole does not have a significant advantage over omeprazole in h. pylori eradication , drug costs of lansoprazole are more expensive than those of omeprazole . niv also reported that there was no statistically significant difference between omeprazole and lansoprazole as part of a ppi - based triple therapy for eradication of h. pylori . the costs of clr for 7 days are five times more expensive than those of mnz for 7 days . drug costs of omeprazole , mnz , and amx for 7 days are $ 46 , and those of lansoprazole , clr , and amx for 7 days are $ 76 . the 7-day regimen of omeprazole , mnz , and amx would save $ 30 per a patient treated . the present study demonstrated that the high eradication rate could be achieved despite of its low cost . in conclusion , the triple therapy with ppi , mnz , and amx appeared to serve as an encouraging first - line strategy in japan . given the recent surge of clr resistance compared to mnx resistance , new strategies for first - line regimens against h. pylori infection should be considered .
the aim of this study was to compare the efficacy and tolerability of the first - line helicobacter pylori ( h. pylori ) eradication regimen composed of proton pump inhibitor , clarithromycin , and amoxicillin , with those of a regimen composed of proton pump inhibitor , metronidazole , and amoxicillin . 
 data of patients , who were administered the first - line h. pylori eradication regimen at tokyo medical center between 2008 and 2011 , were reviewed . 
 all patients had h. pylori gastritis without peptic ulcer disease . 
 the 7-day triple regimen composed of lansoprazole , clarithromycin , and amoxicillin was administered to 55 patients , and that composed of omeprazole , metronidazole , and amoxicillin was administered to 55 patients . 
 intention - to - treat and per - protocol eradication rates were 74.5 and 80.4% , respectively , for the regimen of lansoprazole , clarithromycin , and amoxicillin , whereas the corresponding rates were 96.4 and 100% , respectively , for the regimen of omeprazole , metronidazole , and amoxicillin . in conclusion , 
 first - line h. pylori eradication therapy composed of omeprazole , metronidazole , and amoxicillin was significantly more effective than that composed of lansoprazole , clarithromycin , and amoxicillin , without differences in tolerability .