***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 To analyze the effectiveness of a second-line treatment of Helicobacter pylori infection in patients with duodenal ulcer based on previous antibiotic regimen . PATIENTS AND METHODS Open , prospect i ve , uncontrolled study , but guided by protocol including 30 consecutive patients with endoscopic diagnosis of active duodenal ulcer and failure of a first-line H. pylori eradication treatment diagnosed by urea breath test or a new endoscopy with histology and positive urease test . Treatment consisted in 10 days with omeprazole ( 20 mg/12 h ) , bismuth subcitrate ( 120 mg/6 h ) , tetracycline ( 500 mg/6 h ) and metronidazole ( 500 mg/8 h ) ( OBTM ) if previous regimen was with clarithromycin ; or 10 days with omeprazole ( 20 mg/12 h ) , clarithromycin ( 500 mg/12 h ) and amoxycillin ( 1g/12 h ) ( OCA ) if previous regimen did not include clarithromycin ; using metronidazole ( 500 mg/8 h ) instead of amoxycillin ( OCM ) in case of allergy . Eradication was defined as a negative 13C-urea breath test 2 months after the end of therapy . RESULTS One patient had to stop treatment due to the side effects and in 2 patients urea breath test was not performed ( 3 patients due to the OBTM group ) . Per protocol eradication was achieved in 25 out of 27 patients ( 92.6 % ) and by intention-to-treat eradication was attained in 25 out of 30 cases ( 83.3 % ) . When both groups analyzed separately , the OCA combination was successful in 5 from 6 patients ( 83.3 % ; 95 % CI 35.9 - 99.6 ) ; while the OBTM combination was successful in 20 from 21 valuable patients ( 95 . 2 % ; 95 % CI 76.2 - 99.9 ) . In this second case we make an intention to treat analysis and eradication was achieved in 20 from 24 ( 83.3 % ; 95 % CI 62.6 - 95.3 ) . CONCLUSION The eradicative treatment for H. pylori based in different antibiotics used in subsequent attempts get high eradication rates in patients with duodenal ulcer To the Editor H. pylori is a very common infection worldwide and has a substantial role in the development of gastritis , peptic ulcer , and gastric malignancies . Eradication rates of firstline regimens have been reduced in less than 80 % during the last decade because of the increasing prevalence of antibiotic resistance . A 10-day sequential treatment containing a proton pump inhibitor ( PPI ) and amoxicillin for 5 days followed by a PPI , clarithromycin and tinidazole for an additional 5 days , has been proven to be very effective , achieving per- protocol ( PP ) cure rates around 90 % [ 1 ] . Levofloxacin-based regimens have recently been shown to be encouraging second-line options . In a meta- analysis , levofloxacin triple therapy had higher eradication rates and was better tolerated compared to the quadruple therapy [ 2 ] . The aim of this pilot study was to evaluate the efficacy and tolerability of a 10-day sequential second-line levofloxacin-based regimen and to compare it to the usually prescribed 10-day concomitant one in patients after one H. pylori eradication failure . Fifty-six patients ( F : 30 , M : 26 ; mean age : 52 , range : 18–75 years ) were r and omized to receive either a 10-day treatment with omeprazole 20 mg b.i.d . , amoxicillin 1 g b.i.d . and levofloxacin 500 mg b.i.d . ( group A ) or a sequential 10-day treatment as follows : ( a ) from day 1 to 5 : omeprazole 20 mg b.i.d . and amoxicillin 1 g b.i.d . ( b ) from day 6 to 10 : omeprazole 20 mg b.i.d . and levofloxacin 500 mg b.i.d . ( group B ) . H. pylori eradication was confirmed with a negative breath test performed at least 4 weeks after treatment end . Success rates were 72.4 % ( 21/29 ) ( 95 % CI : 52.8–87.2 % ) and 77.8 % ( 21/27 ) ( 95 % CI : 57.7–91.4 % ) in groups A and B , respectively , in the intention-to-treat analysis and 80.8 % ( 21/26 ) ( 95 % CI : 60.7–93.5 % ) and 84 % ( 21/25 ) ( 95 % CI : 63.9–95.5 % ) , respectively , in the per- protocol analysis ( p [ 0.05 , NS ) . Three patients failed to complete the treatment because of severe allergic reaction and another seven complained of minor side-effects . However , no significant differences were observed between the two groups concerning adverse effects . The idea of a sequential regimen was launched in Mediterranean countries in an attempt to provide a more effective first-line and relatively simple therapy against H. pylori . In a meta- analysis , Essa et al. proved that a 10-day concomitant regimen with three antibiotics ( amoxicillin , clarithromycin , and tinidazole ) was superior over triple therapy and concluded that it was less complex than the sequential one [ 3 ] . To the best of our knowledge , our study is the first one to evaluate a second-line sequential , levofloxacin-based treatment , including patients where there was a failure to eradicate H. pylori after classical triple therapy . Aydin et al. treated both naive and previous treatment failures with a modified 14-day sequential regimen using rabeprazole and amoxicillin for 7 days , and rabeprazole , levofloxacin , and metronidazole for another 7 days and found acceptable eradication rates only in naive patients [ 4 ] . Graham et al. used a 12-day sequential therapy with high dose of esomeprazole and amoxicillin followed by gatifloxacin and showed that this was effective . However , in contrast to our study , amoxicillin was given during the whole period and patients were both naive and previous failures [ 5 ] . Minor adverse effects of levofloxacin can occur in up to 22 % of the patients [ 6 ] . Although we did not observe any differences between the two groups , other authors found significantly less C. Krystallis ( & ) D. Kamberoglou D. Pistiolas C. Anifanti A. Koutsoumbas V. Doulgeroglou V. Tzias Department of Gastrointestinal Endoscopy , 1st IKA Hospital , End of Z aim i Str , 15127 Melissia , Athens , Greece e-mail : Abstract Objective . To test the efficacy of lansoprazole , bismuth , levofloxacin , and amoxicillin therapy compared to bismuth metronidazole tetracycline ( BMT ) quadruple therapy for second-line treatment of Helicobacter pylori infection . Methods . A total of 284 patients who failed prior H. pylori eradication were r and omized to receive 14-day regimens containing lansoprazole 30 mg twice a day ( b.i.d . ) , bismuth subcitrate 240 mg b.i.d . , and either amoxcillin , 1 g b.i.d . and levofloxacin 500 mg once daily ( qd ) ( levofloxacin/bismuth therapy ) or metronidazole 400 mg four times daily ( q.i.d . ) and tetracycline , 500 mg q.i.d . ( BMT quadruple therapy ) . Endoscopy and culture were performed before treatment . Antimicrobial susceptibility was by agar dilution . H. pylori status was determined 6 weeks after the end of therapy using a 13C-urea breath test . Results . The metronidazole , levofloxacin , tetracycline , and amoxicillin resistance rates were 85.3 % , 40.2 % , 1.1 % , and 0.5 % , respectively . The intention-to-treat and per- protocol ( PP ) eradication rates were 83 % ( 95 % confidence interval [ CI ] : 75.9–88.3 % ) and 88.1 % ( 95 % CI : 81.2–92.4 % ) ( p = 0.22 ) for levofloxacin-bismuth ( levo-bismuth ) versus BMT quadruple , respectively , and PP rates were 85.4 % ( 95 % CI : 78.5–90.3 % ) and 90.6 % ( 95 % CI : 84.6–94.5 % ) ( p = 0.18 ) . Moderate and severe side effects were significantly higher with BMT quadruple than levo-bismuth ( 22.4 % vs. 5 % , p < 0.001 ) and higher in women ( 28.4 % ) than men ( 10.4 % ) in BMT quadruple therapy group ( p = 0.015 ) . Conclusion . Increasing fluoroquinolone resistance has undermined levo-bismuth quadruple therapy making BMT quadruple therapy a better choice empiric second-line therapy for H. pylori infection . However , compliance was significantly higher with levo-bismuth quadruple therapy , especially among women The bismuth-based quadruple regimen has been applied in Helicobacter pylori rescue therapy worldwide . The non-bismuth-based quadruple therapy or “ concomitant therapy ” is an alternative option in first-line eradication but has not been used in second-line therapy . Discovering a valid regimen for rescue therapy in bismuth-unavailable countries is important . We conducted a r and omized controlled trial to compare the efficacies of the st and ard quadruple therapy and a modified concomitant regimen .  One hundred and twenty-four patients were r and omly assigned into two groups : RBTM ( rabeprozole 20 mg bid . , bismuth subcitrate 120 mg qid , tetracycline 500 mg qid , and metronidazole 250 mg qid ) and RATM ( rabeprozole 20 mg bid . , amoxicillin 1 g bid . , tetracycline 500 mg qid , and metronidazole 250 mg qid ) for 10 days . The eradication rate of the RBTM and RATM regimen was 92.1 % and 90.2 % , respectively , in intention-to-treat analysis . Patients in both groups had good compliance ( ~96 % ) . The overall incidence of adverse events was higher in the RATM group ( 42.6 % versus 22.2 % , P = 0.02 ) , but only seven patients ( 11.5 % ) experienced grade s 2 - 3 events . In conclusion , both regimens had good efficacy , compliance , and acceptable side effects . The 10-day RATM treatment could be an alternative rescue therapy in bismuth-unavailable countries Background / Aims Several rescue therapies have been recommended to eradicate Helicobacter pylori infection in patients with a failure of first-line eradication therapy , but they still fail in more than 20 % of cases . The aim of this study was to evaluate the efficacy and safety of levofloxacin , metronidazole , and lansoprazole ( LML ) triple therapy relative to quadruple therapy as a second-line treatment . Methods In total , 113 patients who failed first-line triple therapy for H. pylori infection were r and omly assigned to two groups : LML for 7 days and tetracycline , bismuth subcitrate , metronidazole and lansoprazole ( quadruple ) for 7 days . Results According to intention-to-treat analysis , the infection was eradicated in 38 of 56 patients ( 67.9 % ) in the LML group and 48 of 57 ( 84.2 % ) in the quadruple group ( p=0.042 ) . Per- protocol analysis showed successful eradication in 38 of 52 patients ( 73.1 % ) from the LML group and 48 of 52 ( 92.3 % ) from the quadruple group ( p=0.010 ) . There were no significant differences in the adverse effects in either treatment group . Conclusions LML therapy is less effective than quadruple therapy as a second-line treatment for H. pylori infection . Therefore , quadruple therapy should be considered as the primary second-line strategy for patients experiencing a failure of first-line H. pylori therapy in Korea Background Increasing resistance to clarithromycin and nitroimidazole is the main cause of failure in the Helicobacter pylori eradication . The ideal retreatment regimen remains unclear , especially in developing countries , where the infection presents high prevalence and resistance to antibiotics . The study aim ed at determining the efficacy , compliance and adverse effects of a regimen that included fur 
    Output:
    
The meta-regression did not find any particular characteristics of the studies to be associated with excellent cure rates .
CONCLUSION Second-line Helicobacter pylori treatments achieving>90 % cure rates are extremely heterogeneous .
Quadruple therapy and 14-day treatments seem better than triple therapies and 7-day ones .
No single characteristic of the treatments was related to excellent cure rates .