***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 : An  antimicrobial susceptibility test  for Helicobacter pylori before second‐line treatment is often performed , although whether the test is truly necessary remains unknown BACKGROUND & AIMS The major obstacle to 100 % effective eradication of Helicobacter pylori infection is represented by antimicrobial-resistant H. pylori strains . This r and omized study was design ed to evaluate whether regimens based on pretreatment susceptibility testing were more effective and cost saving compared with st and ard nonsusceptibility testing-based therapy in the eradication of H. pylori infection . METHODS We studied 150 consecutive H. pylori-infected dyspeptic subjects . Patients were r and omly assigned to omeprazole 20 mg twice daily , clarithromycin 500 mg twice daily , and metronidazole 500 mg twice daily for 7 days or to omeprazole 20 mg twice daily and 2 antimicrobials chosen based on susceptibility testing . H. pylori status was reevaluated 12 weeks after the end of treatment by the (13)C-urea breath test . RESULTS Susceptibility testing-based regimens led to the following results . ( 1 ) Eradication rates were 97.3 % ( 95 % confidence interval [ CI ] , 91.2%-99.5 % ) ( 71 of 73 ) and 94.6 % ( 95 % CI , 87.6%-98.3 % ) ( 71 of 75 ) in the per- protocol and intention-to-treat analysis , respectively . These were significantly higher ( P < 0.005 ) than eradication rates obtained without susceptibility testing , that is , 79.4 % ( 95 % CI , 69.1%-87.6 % ) ( 58 of 73 ) and 77.3 % ( 95 % CI , 66.9%-85.7 % ) ( 58 of 75 ) in the per- protocol and intention-to-treat analyses , respectively . ( 2 ) There were savings of approximately $ 5 U.S. per patient compared with st and ard triple therapy . CONCLUSIONS Pretreatment antimicrobial susceptibility testing is more effective and cost saving and , in health systems that confirm cost advantage , microbial susceptibility testing should be routinely used for eradication of H. pylori infection Helicobacter pylori eradication rates by triple therapy with a proton pump inhibitor , amoxicillin , and clarithromycin at st and ard doses depend on bacterial susceptibility to clarithromycin and patient CYP2C19 genotypes . We examined the usefulness of a personalized therapy for H. pylori infection based on these factors as determined by genetic testing . First , optimal lansoprazole dosing schedules that would achieve sufficient acid inhibition to allow H. pylori eradication therapy in each of different CYP2C19 genotype groups were determined by a 24‐h intragastric pH monitoring . Next , 300 H. pylori‐positive patients were r and omly assigned to the st and ard regimen group ( lansoprazole 30 mg twice daily ( b.i.d . ) ) , clarithromycin 400 mg b.i.d . , and amoxicillin 750 mg b.i.d . for 1 week ) or the tailored regimen group based on CYP2C19 status and bacterial susceptibility to clarithromycin assessed by genetic testing . Patients with failure of eradication underwent the second‐line regimen . The per‐patient cost required for successful eradication was calculated for each of the groups . In the first‐line therapy , the intention‐to‐treat eradication rate in the tailored regimen group was 96.0 % ( 95 % CI=91.5–98.2 % , 144/150 ) , significantly higher than that in the st and ard regimen group ( 70.0 % : 95 % CI=62.2–77.2 % , 105/150 ) ( P<0.001 ) . Final costs per successful eradication in the tailored and st and ard regimen groups were $ 669 and $ 657 , respectively . In conclusion , the pharmacogenomics‐based tailored treatment for H. pylori infection allowed a higher eradication rate by the initial treatment without an increase of the final per‐patient cost for successful eradication . However , the precise cost‐effectiveness of this strategy remains to be determined BACKGROUND Clarithromycin-resistant Helicobacter pylori is associated with point mutations in the 23S ribosomal RNA ( rRNA ) gene . METHODS A total of 1232 patients participated and were divided into 2 control groups and 1 case group . Patients in the APC control group , which consisted of 308 r and omly assigned participants , were treated with st and ard triple therapy , consisting of amoxicillin , rabeprazole , and clarithromycin ;  308 participants in the APM control group were treated with amoxicillin , rabeprazole , and metronidazole . For the 616 participants in the case group , a test for point mutations in the 23S rRNA gene of H. pylori was conducted . A total of 218 individuals in the case group received a new tailored therapy regimen , in which amoxicillin , rabeprazole , and clarithromycin were given in the absence of a mutation , whereas clarithromycin was replaced by metronidazole if the mutation was detected . RESULTS The rate of eradication of H. pylori in the tailored group was 91.2 % ( 176/193 ) , which was significantly higher than that in the APC ( 75.9 % [ 214/282 ] ; P < .001 ) and APM ( 79.1 % [ 219/277 ] ; P < .001 ) control groups . CONCLUSION The rate of H. pylori eradication among patients who received tailored therapy on the basis of detection of a clarithromycin resistance mutation by polymerase chain reaction was much higher than the rate among patients who received a st and ard triple therapy regimen . CLINICAL TRIALS REGISTRATION NCT0145303 Helicobacter pylori eradication therapies do not achieve 100 % success rates . Antibiotic resistant strains are among the major causes of failure . Current recommendations concerning the management of treatment failures are not fully clear AIM : Eradication therapy with proton pump inhibitor , clarithromycin and amoxicillin fails in a considerable number of cases . A rescue therapy still fails in more than 20 % of the cases . Our aim was to evaluate the efficacy and tolerability of a third-line levofloxacin-based regimen in patients with two consecutive Helicobacter pylori eradication failures . METHODS : Design : Prospect i ve multicenter study . Patients : In whom a first treatment with omeprazole-clarithromycin-amoxicillin and a second with omeprazole-bismuth-tetracycline-metronidazole ( or ranitidine bismuth citrate with these antibiotics ) had failed . Intervention : A third eradication regimen with levofloxacin ( 500 mg b.i.d . ) , amoxicillin ( 1 g b.i.d . ) , and omeprazole ( 20 mg b.i.d . ) was prescribed for 10 days . Outcome : Eradication was confirmed with 13C-urea breath test 4–8 wk after therapy . RESULTS : One-hundred patients were initially included , and nine were lost for follow-up . All patients but five took all the medications correctly . Per- protocol and intention-to-treat eradication rates were 66 % ( 95 % CI = 56–75 % ) and 60 % ( 50–70 % ) . Adverse effects were reported in 25 % of the patients , mainly including metallic taste ( 8 % ) , nausea ( 8 % ) , myalgia/arthralgia ( 5 % ) , and diarrhea ( 4 % ) ; none of them were severe . CONCLUSION : Levofloxacin-based rescue therapy constitutes an encouraging empirical third-line strategy after multiple previous H. pylori eradication failures with key antibiotics such as amoxicillin , clarithromycin , metronidazole , and tetracycline Successful eradication of Helicobacter pylori after failure of st and ard triple therapy is difficult because of the higher resistance to metronidazole and clarithromycin . We evaluated the efficacy of susceptibility-guided vs. empiric retreatment for H. pylori after at least one treatment failure and determined the prevalence of posttreatment antibiotic resistance .  Forty-nine patients in whom at least one treatment regimen for H. pylori eradication had failed underwent gastric biopsy and culture  and were retreated according to the in vitro susceptibility results . Findings were compared with those for 49 control patients referred to our center for a 13C-urea breath test .  H. pylori eradication was assessed by urea breath test at least 6 weeks after retreatment in both groups . Susceptibility-guided retreatment was associated with better eradication rates than empiric treatment . The difference remained significant in stratified and multivariate analysis . Susceptibility-guided retreatment appears to be significantly more effective than empiric retreatment in eradicating H. pylori after at least one previous treatment failure BACKGROUND Levofloxacin has been proposed as an alternative to classic therapy in secondary resistance to Helicobacter pylori . AIM To evaluate primary and secondary resistance of H. pylori to levofloxacin , and to test the role of susceptibility test on the efficacy of levofloxacin-based triple therapy . METHODS Eighty consecutive dyspeptic patients with positive (13)C-urea breath test never treated were r and omly allocated into group A(1 ) ( 40 patients ) and group B(1 ) ( 39 patients ) . Eighty-three patients already treated unsuccessfully with positive (13)C-urea breath test were divided into group A(2 ) ( 51 patients ) and group B(2 ) ( 32 patients ) . Patients in group A(1 ) and group A(2 ) underwent upper gastrointestinal endoscopy for H. pylori susceptibility test to amoxicillin , clarithromycin , tinidazole , rifabutin , and levofloxacin . These patients were treated with levofloxacin ( 500 mg b.i.d . ) , amoxicillin ( 1 g b.i.d . ) and esomeprazole ( 20 mg b.i.d . ) for 10 days if sensitive to these two antibiotics . If H. pylori was found resistant to amoxicillin and /or levofloxacin the treatment was based on the indications of the susceptibility test . Patients in group B(1 ) and group B(2 ) were treated empirically with levofloxacin , amoxicillin , and esomeprazole at the same dose and duration as group A. All patients underwent (13)C-urea breath test 2 months after the end of therapy . RESULTS The antibiotic resistance of H. pylori strains in group A(1 ) and group A(2 ) was ( % ) : amoxicillin : 2.4 , 10 ; clarithromycin : 21.9 , 43.1 ; tinidazole : 31.7 , 70 ; rifabutin : 2.4 , 4 ; and levofloxacin : 9.7 , 12.2 , respectively . In group A(1 ) with susceptibility test-driven therapy , eradication was 97.2 % , and in group B(1 ) with empirical treatment , 94.1 % ( n.s . ) . In group A(2 ) with susceptibility test , eradication was 97.5 % , whereas in group B(2 ) with empirical treatment 81.2 % ( p < .01 ) . CONCLUSION Primary and secondary resistance of H. pylori to levofloxacin is approximately 10 % of the tested strains . The susceptibility test does not influence therapeutic outcome of triple therapy with amoxicillin and levofloxacin in patients never treated , while it is determinant for patients who were previously treated without success BACKGROUND & AIMS Eradication of Helicobacter pylori using empiric therapy has become difficult as a result of increasing resistance to antibiotics . We evaluated the efficacy of specific treatments , selected based on response of bacterial sample s to culture with clarithromycin , levofloxacin , and metronidazole , for patients infected with resistant strains of H pylori . METHODS We performed a prospect i ve study at a single center of 236 consecutive patients with persistent H pylori infection , despite 1 or more treatment attempts , and documented resistance to at least 1 antimicrobial agent ( based on bacterial culture tests ) . Biopsy sample s were collected by endoscopy and cultured in selective media . Patients received either 10 days of levofloxacin ( 250 mg twice daily for 131 patients with susceptible infections ) or 12 days of rifabutin ( 150 mg once daily for 105 patients resistant to levofloxacin ) in combination with amoxicillin ( 1 g twice daily ) and esomeprazole ( 4 
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Conclusions : SGT may be an acceptable option as rescue treatment .
However , cure rates are , at best , moderate and this approach has never been compared with a well-devised empirical therapy .
The evidence in favor of SGT as rescue therapy is currently insufficient to recommend its use