Rescue therapy using a rifabutin-based regimen is effective for cure of Helicobacter pylori infection

Efficacy and safety of low-dose rifabutin-based 7-day triple therapy as a third- or later-line Helicobacter pylori eradication regimen

BACKGROUND

Rifabutin-based regimens are used as rescue therapy for refractory Helicobacter pylori infection; however, the duration for which treatment is required and side effects are concerning. This study assessed the efficacy and safety of 7-day rifabutin, amoxicillin, and vonoprazan triple therapy as third- or later-line treatment for H. pylori infection.

MATERIALS AND METHODS

Patients who did not respond to second-line therapy were enrolled. After H. pylori infection was confirmed with the culture method, the patients received rifabutin-containing triple therapy (20 mg vonoprazan b.i.d., 500 mg amoxicillin q.i.d., and 150 mg rifabutin q.d.) for 7 days. Twelve weeks after the eradication therapy, successful eradication was confirmed using a ¹³ C urea breath test or the H. pylori stool antigen test. The results obtained from our previous study that reported a 10-day or 14-day esomeprazole based rifabutin-containing triple therapy as a third- or fourth-line rescue therapy treated patients were used as historical control. We determined the minimum inhibitory concentrations of amoxicillin and rifabutin. We also evaluated whether the patients were positive for the mutation of the rpoB gene.

RESULTS

Intention-to-treat and per-protocol analyses showed that our regimen resulted in a high eradication rate (91.2%, 95% CI: 84%-99% and 92.7%, 95% CI: 86%-100%, respectively). Adverse events occurred in 31.6% of the patients, and two patients discontinued the therapy.

CONCLUSIONS

This is the first study to evaluate the efficacy and safety of a 7-day low-dose rifabutin-based triple therapy with vonoprazan and amoxicillin. Our results suggest that our regimen was effective and safe as a third- or later-line H. pylori eradication regimen. To clarify what component in this regimen are critical, subsequent studies using a factorial design (comparing vonoprazan-amoxicillin dual therapy vs. vonoprazan-rifabutin triple therapy) will be needed.

V Spanish Consensus Conference on Helicobacter pylori infection treatment

Helicobacter pylori infection is very common in the Spanish population and represents the main cause of chronic gastritis, peptic ulcer, and gastric cancer. The last iteration of Spanish consensus guidelines on H. pylori infection was conducted in 2016. Recent changes in therapeutic schemes along with increasing supporting evidence were key for developing the V Spanish Consensus Conference (May 2021). Fourteen experts performed a systematic review of the scientific evidence and developed a series of recommendations that were subjected to an anonymous Delphi process of iterative voting. Scientific evidence and the strength of the recommendation were classified using GRADE guidelines. An eradication therapy, when prescribed empirically, is considered acceptable when it reliably achieves, or preferably surpass, 90% cure rates. Currently, only quadruple therapies (with or without bismuth) and generally lasting 14 days, accomplish this goal in first- and second-line therapies. A non-bismuth quadruple concomitant regimen (proton pump inhibitor, clarithromycin, amoxicillin, and metronidazole) or a quadruple bismuth-based combination (proton pump inhibitor, bismuth, tetracycline, and metronidazole), are recommended as first-line regimens. Rescue therapies after eradication failure and management of H. pylori infection in peptic ulcer disease were also reviewed.

Evaluating treatments with rifabutin and amoxicillin for eradication of Helicobacter pylori infection in adults: a systematic review

INTRODUCTION

Helicobacter pylori causes dyspepsia, peptic ulcer, and gastric malignancies. Treatments for Helicobacter pylori are mostly empirical depending on regional antibiotic resistances and the patient's history and less frequently susceptibility guided. Helicobacter pylori has a low resistance to rifabutin and has been proposed as an alternative for third-line treatment and beyond but recently has also gained attention for use as first- and second-line treatment.

AREAS COVERED

In this review, the authors systematically searched medical databases in order to present the current eradication rates for any treatment based on the two antibiotics, rifabutin and amoxicillin with a potent acid inhibitor. They also assessed the safety and tolerance of all the relative regimens.

EXPERT OPINION

Treatment with a rifabutin- and amoxicillin-containing regimen is a valuable option when treating difficult to eradicate Helicobacter pylori infections. Its efficacy is overall 71.4%, and it is not influenced by previous antibiotics, gender, smoking habits, and age. Its results were better when used as a first- or second-line treatment. In third-line therapy and beyond, eradication rates are lower. Adverse effects of all rifabutin regimens occurred in 23% of patients and were mostly mild with bone marrow suppression being very low and reversible.

Rifabutin triple therapy for first-line and rescue treatment of Helicobacter pylori infection: A systematic review and meta-analysis

BACKGROUND AND AIM

Due to the increasing resistance of Helicobacter pylori, there is a need for novel antibiotic treatment protocols. We aimed to perform a systematic review and meta-analysis in order to determine the effectiveness and safety of rifabutin triple therapy for H. pylori infection.

METHODS

We performed a systematic review of prospective clinical trials with a treatment arm consisting of proton pump inhibitor, amoxicillin, and rifabutin and a meta-analysis of randomized controlled trials (RCTs).

RESULTS

Thirty-three prospective studies including 44 datasets were identified. Meta-analysis of four RCTs for rescue treatment found no difference between treatment groups (odds ratio [OR] 0.88, 95% confidence interval [CI] 0.437-1.791, I²  = 68.1%, P = 0.733). Only one RCT compared rifabutin therapy with control for first-line treatment of H. pylori infection (OR 3.78, 95% CI 2.44-5.87, P < 0.0001). Treatment was more likely to be successful in Asian versus non-Asian populations (81.0% vs 72.4%, P = 0.001) and when daily amoxicillin dose was ≥ 3000 mg or proton pump inhibitor dose was ≥ 80 mg or treatment duration was 14 days (80.6% vs 66.0%, P = 0.0001). The overall event rate for adverse effects was 24.8% (729/2937) (95% CI 0.23-0.26), and the pooled OR for adverse effects in the treatment versus control group was 0.93 (95% CI 0.50-1.75) (I²  = 79.76, P = 0.82).

CONCLUSION

Evidence for the effectiveness of rifabutin for the first-line treatment of H. pylori infection in adults is limited, and studies comparing rifabutin with conventional first-line treatments are lacking.

Rifabutin for the Treatment of Helicobacter Pylori Infection: A Review

Nowadays, apart from having to know first-line Helicobacter pylori eradication regimens well, we must also be prepared to face treatment failures. The aim of this review is to summarize the role of rifabutin in the management of H. pylori infection. Bibliographical searches were performed in PubMed. Data on resistance and efficacy of rifabutin-containing regimens on H. pylori eradication were meta-analyzed. Mean H. pylori rifabutin resistance rate (39 studies, including 9721 patients) was 0.13%; when studies only including patients naïve to H. pylori eradication treatment were considered, this figure was even lower (0.07%). Mean H. pylori eradication rate (by intention-to-treat) with rifabutin-containing regimens (3052 patients) was 73%. Respective cure rates for second-, third-, fourth- and fifth-line therapies, were 79%, 69%, 69% and 72%. Most studies administered rifabutin 300 mg/day, which seemed to be more effective than 150 mg/day. The ideal length of treatment remains unclear, but 10–12-day regimens are generally recommended. Adverse events to rifabutin treatment in H. pylori studies were relatively infrequent (15%), and severe adverse events were exceptional (myelotoxicity was the most significant, although always reversible). In summary, rifabutin-containing therapy represents an encouraging strategy generally restricted, at present, to patients where previous (usually multiple) eradication regimens have failed.

Efficacy and safety of a new rifabutin-based triple therapy with vonoprazan for refractory Helicobacter pylori infection: A prospective single-arm study

BACKGROUND

A small proportion of Helicobacter pylori-infected individuals in Japan suffer failure of eradication therapy with third-line regimens containing the potent acid suppressor, vonoprazan, and a quinolone.

OBJECTIVES

This prospective study evaluated the efficacy and safety of rifabutin-based triple therapy with vonoprazan for refractory H pylori infection.

METHODS

Patients who failed H pylori eradication by clarithromycin-based first-line, metronidazole-based second-line, and sitafloxacin-based third-line therapies were recruited. After obtaining informed consent, patients received eradication therapy with vonoprazan (20 mg), amoxicillin (750 mg), and rifabutin (150 mg) twice daily for 10 days. Eradication was confirmed by a negative H pylori stool antigen or urea breath test at least 8 weeks after the end of therapy.

RESULTS

Nineteen patients were included in the study. All of the patients completed the course of medication. Eradication of H pylori was confirmed in all of the patients (19/19; 100%, 95% confidence interval; 83-100%). The most common adverse event was soft stool/diarrhea (4/19, 21%). No severe adverse event was observed.

CONCLUSIONS

Ten-day rifabutin with amoxicillin and vonoprazan triple therapy appears to be effective and safe for refractory H pylori infections. However, considering the recent publications showing high eradication rates with vonoprazan amoxicillin dual therapy, confirmation will require future studies comparing our new therapy with vonoprazan-amoxicillin dual with similar doses and duration and with vonoprazan-rifabutin dual therapy.

Rescue therapy with rifabutin regimen for refractory Helicobacter pylori infection with dual drug-resistant strains

Background

There is no current standard rescue treatment for dual drug-resistant strains of Helicobacter pylori (H. pylori). This aim of this study was to investigate the efficacy of rifabutin-based triple therapy for patients infected with dual drug-resistant strains to clarithromycin and levofloxacin.

Methods

After 2 or 3 H. pylori treatment failures, patients underwent upper endoscopy with tissue biopsies. Phenotypic and genotypic resistances were determined using agar dilution test and polymerase chain reaction with direct sequencing, respectively. Patients infected with dual drug-resistant (clarithromycin and levofloxacin) strains and receiving rifabutin-based triple therapy (rifabutin 150 mg bid, amoxicillin 1 g bid and esomeprazole 40 mg bid for 10 days) were enrolled. Eradication status was determined by 13C-urea breath test 4 weeks after treatment completion.

Results

A total of 39 patients infected with dual drug-resistant strains were enrolled in this study, with a mean age of 55.9 years. The eradication rate was 79.5% (31/39) (95% confidence intervals: 54.96% ~ 111.40%). Adverse event was reported in 23.1% (9/39) of patients but they were mild and tolerable. In univariate analysis, no factor was identified as an independent predictor of eradication failure.

Conclusions

Our current study demonstrated that rifabutin-based triple therapy was well tolerated and yielded an acceptable eradication rate for patients infected with dual drug-resistant strains of H. pylori.

Antibiotic susceptibility, heteroresistance, and updated treatment strategies in Helicobacter pylori infection

In this review, we discuss the problem of antibiotic resistance, heteroresistance, the utility of cultures and antibiotic susceptibility tests in Helicobacter pylori (Hp) eradication, as well as the updated treatment strategies for this infection. The prevalence of antibiotic resistance is increasing all over the world, especially for metronidazole and clarithromycin, because of their heavy use in some geographical areas. Heteroresistance (simultaneous presence of both susceptible and resistant strains in different sites of a single stomach) is another important issue, as an isolate could be mistakenly considered susceptible if a single biopsy is used for antimicrobial tests. We also examined literature data regarding eradication success rates of culture-guided and empiric therapies. The empiric therapy and the one based on susceptibility testing, in Hp eradication, may depend on several factors such as concomitant diseases, the number of previous antibiotic treatments, differences in bacterial virulence in individuals with positive or negative cultures, together with local antibiotic resistance patterns in real-world settings. Updated treatment strategies in Hp infection presented in the guidelines of the Toronto Consensus Group (2016) are reported. These suggest to prolong eradication therapy up to 14 days, replacing the old triple therapy with a quadruple therapy based on proton pump inhibitor (PPI), bismuth, metronidazole, and tetracycline for most of the patients, or as an alternative quadruple therapy without bismuth, based on the use of PPI, amoxicillin, metronidazole, and clarithromycin. The new drug vonoprazan, a first-in-class potassium-competitive acid blocker recently approved in Japan, is also considered to be a promising solution for Hp eradication, even for clarithromycin-resistant strains. Furthermore, there is growing interest in finding new therapeutic strategies, such as the development of vaccines or the use of natural resources, including probiotics, plants, or nutraceuticals.

The Toronto Consensus for the Treatment of Helicobacter pylori Infection in Adults

BACKGROUND & AIMS

Helicobacter pylori infection is increasingly difficult to treat. The purpose of these consensus statements is to provide a review of the literature and specific, updated recommendations for eradication therapy in adults.

METHODS

A systematic literature search identified studies on H pylori treatment. The quality of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation (GRADE) approach. Statements were developed through an online platform, finalized, and voted on by an international working group of specialists chosen by the Canadian Association of Gastroenterology.

RESULTS

Because of increasing failure of therapy, the consensus group strongly recommends that all H pylori eradication regimens now be given for 14 days. Recommended first-line strategies include concomitant nonbismuth quadruple therapy (proton pump inhibitor [PPI] + amoxicillin + metronidazole + clarithromycin [PAMC]) and traditional bismuth quadruple therapy (PPI + bismuth + metronidazole + tetracycline [PBMT]). PPI triple therapy (PPI + clarithromycin + either amoxicillin or metronidazole) is restricted to areas with known low clarithromycin resistance or high eradication success with these regimens. Recommended rescue therapies include PBMT and levofloxacin-containing therapy (PPI + amoxicillin + levofloxacin). Rifabutin regimens should be restricted to patients who have failed to respond to at least 3 prior options.

CONCLUSIONS

Optimal treatment of H pylori infection requires careful attention to local antibiotic resistance and eradication patterns. The quadruple therapies PAMC or PBMT should play a more prominent role in eradication of H pylori infection, and all treatments should be given for 14 days.

IV Spanish Consensus Conference on Helicobacter pylori infection treatment

Helicobacter pylori approximately infect 50% of Spanish population and causes chronic gastritis, peptic ulcer and gastric cancer. Until now, three consensus meetings on H.pylori infection had been performed in Spain (the last in 2012). The changes in the treatment schemes, and the increasing available evidence, have justified organizing the IVSpanish Consensus Conference (March 2016), focused on the treatment of this infection. Nineteen experts participated, who performed a systematic review of the scientific evidence and developed a series of recommendation that were subjected to an anonymous Delphi process of iterative voting. Scientific evidence and the strength of the recommendation were classified using GRADE guidelines. As starting point, this consensus increased the minimum acceptable efficacy of recommended treatments that should reach, or preferably surpass, the 90% cure rate when prescribed empirically. Therefore, only quadruple therapies (with or without bismuth), and generally lasting 14 days, are recommended both for first and second line treatments. Non-bismuth quadruple concomitant regimen, including a proton pump inhibitor, clarithromycin, amoxicillin and metronidazole, is recommended as first line. In the present consensus, other first line alternatives and rescue treatments are also reviewed and recommended.

Effectiveness of Second through Sixth Line Salvage Helicobacter pylori Treatment: Bismuth Quadruple Therapy is Almost Always a Reasonable Choice

Aim. There is a paucity of data on the efficacy of empiric H. pylori treatment after multiple treatment failures. The aim of this study is to examine the efficacy of empiric salvage therapy as a second through sixth line treatment. Methods. In this single gastroenterology center prospective study in Montreal, Canada, patients with failed H. pylori treatment were offered empiric salvage therapy based on the patients' previous antibiotic exposure. Enrollment occurred after 1-5 previous failed attempts and eradication determined at least 4 weeks after completion of treatment. Results. 205 treatments were attempted in 175 patients using 7 different regimens. Eradication was achieved in 154 attempts (PP = 81% (154/191), ITT = 75% (154/205)). Bismuth quadruple therapy (BQT) had higher eradication success (PP = 91% (102/112), ITT = 84% (102/121)) when compared to all PPI triple therapies combined (PP = 66% (49/74), absolute risk reduction (ARR): 25% (95% CI: 13-37), ITT = 62% (49/79), ARR: 22% (95% CI: 10-35), and p < 0.001) and when compared to levofloxacin triple therapy (PP = 66% (40/61), ARR: 26% (95% CI: 13-39), ITT = 61% (40/66), and ARR: 24% (95% CI: 10-37)). Eradication was achieved in a high proportion with BQT on attempt two (PP = 94% (67/71), ITT = 91% (67/74)), three (PP = 85% (17/20), ITT = 71% (17/24)), four (PP = 100% (11/11), ITT = 92% (11/12)), and five (PP = 86% (6/7), ITT = 75% (6/8)). Patients with previous combined bismuth and tetracycline exposure had a lower proportion of eradication compared to patients without such an exposure (PP: 60% (6/10) versus 95% (94/99), ARR: 35% (95% CI: 11-64), and p < 0.001; ITT: 55% (6/11) versus 90% (94/105), ARR: 35% (95% CI: 10-62), and p < 0.01). Conclusions. Salvage therapy with a bismuth quadruple regimen is superior to triple therapies and is effective for second through fifth line empirical treatment (≥85% PP, ≥70% ITT). Successful eradication is significantly lower with BQT if a similar bismuth based regimen was used in the past.

Rifabutin-based 10-day and 14-day triple therapy as a third-line and fourth-line regimen for Helicobacter pylori eradication: A pilot study

BACKGROUND AND AIM

This prospective randomized study was designed to assess the efficacy of 10-day and 14-day rifabutin-based triple therapy as a third- or fourth-line rescue therapy.

METHODS

Patients who failed first- and second-line eradication therapy were enrolled. H. pylori was isolated from gastric biopsy specimens and the rpoB mutation status, a factor of resistance to rifamycins, and minimum inhibitory concentrations (MICs) of rifabutin and amoxicillin were determined. Enrolled patients were randomly assigned to receive 10-day or 14-day eradication therapy with esomeprazole (20 mg, 4 times a day (q.i.d.)), amoxicillin (500 mg, q.i.d.), and rifabutin (300 mg, once a day (q.d.s.)). Poor compliance was defined as intake of <80% of study drugs. Successful H. pylori eradication was confirmed using a [13C] urea breath test or a stool antigen test, 12 weeks after the end of therapy.

RESULTS

Twelve patients were assigned to the 10-day group, and 17, to the 14-day group. Intention-to-treat and per-protocol analyses of eradication rates were 83.3% and 81.8% for the 10-day group and 94.1% and 91.7% for the 14-day group, respectively. All patients with rpoB mutation-positive strains (n = 3) showed successful eradication, irrespective of the regimen received. Therapy was stopped due to adverse events in 8.3% and 29.3% of patients in the 10-day and 14-day groups, respectively.

CONCLUSION

Both the 10-day and 14-day therapies were effective as rescue regimens. In particular, the 14-day therapy resulted in successful eradication in over 90% of patients, but the 10-day treatment may be enough to obtain a successful eradication rate, considering the tolerability of therapy.

Rescue Therapy with a Proton Pump Inhibitor Plus Amoxicillin and Rifabutin for Helicobacter pylori Infection: A Systematic Review and Meta-Analysis

Background. To conduct a systematic review and meta-analysis of clinical trials for eradication of Helicobacter pylori (H. pylori) that included a treatment arm with a proton pump inhibitor, rifabutin, and amoxicillin. Materials and Methods. We selected clinical trials that examined the efficacy of H. pylori eradication therapies and included a study arm using the test regimen from major medical literature databases and abstracts from major gastroenterology meetings. We also did subgroup and sensitivity analyses. Results. Twenty-one studies were included in systematic review. The total eradication rates of the test regimen were 70.4% by intent-to-treat (ITT) and 72.0% by per-protocol (PP) analyses. The pooled odds ratio (OR) was 0.55 using fixed effects model (P = 0.283) for the test regimen versus other triple regimens. The total eradication rates were 68.4% for the test regimen and 81.9% in the control group by ITT, while the OR was 1.08 using random effects model (P = 0.019). The pooled eradication rate was 66.4% for the test regimen and 67.4% for the control group by ITT. The total adverse effects incidence were 25.1% for the test regimen. Conclusions. The test regimen for H. pylori rescue therapy may be not superior to control regimens in efficacy.

Helicobacter pylori: usefulness of an empirical fourth-line rifabutin-based regimen

Helicobacter pylori represents the major cause of gastric cancer, gastric lymphoma and peptic ulcer diseases. In some cases, the infection persists even after three rounds of treatment. The evaluated article reports on the efficacy of an empirical multicenter, prospective fourth‑line rescue study with rifabutin in patients with three consecutive eradication failures. A total of 100 patients (31% peptic ulcer and 69% functional dyspepsia) were included to receive a fourth‑line with rifabutin (150 mg twice daily [b.i.d.]), amoxicillin (1 g b.i.d.) and a proton‑pump inhibitor (standard dose b.i.d.) for 10 days. The end point was H. pylori eradication, determined by (13)C-urea breath test 4-8 weeks after therapy. H. pylori eradication was achieved in approximately 50% of patients. Adverse events (mainly metallic taste, nausea and diarrhea) were reported in 30 patients. Thus, a fourth-line rifabutin-based rescue therapy constitutes a valid strategy after multiple previous H. pylori eradication failures with key antibiotics, such as clarithromycin, metronidazole, tetracycline and levofloxacin.

Fourth-line rescue therapy with rifabutin in patients with three Helicobacter pylori eradication failures

BACKGROUND

In some cases, Helicobacter pylori infection persists even after three eradication treatments.

AIM

To evaluate the efficacy of an empirical fourth-line rescue regimen with rifabutin in patients with three eradication failures.

DESIGN

Multicentre, prospective study.

PATIENTS

In whom the following three treatments had consecutively failed: first (PPI + clarithromycin + amoxicillin); second (PPI + bismuth + tetracycline + metronidazole); third (PPI + amoxicillin + levofloxacin).

INTERVENTION

A fourth regimen with rifabutin (150 mg b.d.), amoxicillin (1 g b.d.) and a PPI (standard dose b.d.) was prescribed for 10 days.

OUTCOME

Eradication was confirmed by (13) C-urea breath test 4-8 weeks after therapy. Compliance and tolerance: Compliance was determined through questioning and recovery of empty medication envelopes. Adverse effects were evaluated using a questionnaire.

RESULTS

One-hundred patients (mean age 50 years, 39% men, 31% peptic ulcer/69% functional dyspepsia) were included. Eight patients did not take the medication correctly (in six cases due to adverse effects). Per-protocol and intention-to-treat eradication rates were 52% (95% CI = 41-63%) and 50% (40-60%). Adverse effects were reported in 30 (30%) patients: nausea/vomiting (13 patients), asthenia/anorexia (8), abdominal pain (7), diarrhoea (5), fever (4), metallic taste (4), myalgia (4), hypertransaminasemia (2), leucopenia (<1,500 neutrophils) (2), thrombopenia (<150,000 platelets) (2), headache (1) and aphthous stomatitis (1). Myelotoxicity resolved spontaneously in all cases.

CONCLUSIONS

Even after three previous H. pylori eradication failures, an empirical fourth-line rescue treatment with rifabutin may be effective in approximately 50% of the cases. Therefore, rifabutin-based rescue therapy constitutes a valid strategy after multiple previous eradication failures with key antibiotics, such as clarithromycin, metronidazole, tetracycline and levofloxacin.

Review article: rifabutin in the treatment of refractory Helicobacter pylori infection

BACKGROUND

Even with the current most effective treatment regimens, a relevant proportion of patients will fail to eradicate Helicobacter pylori infection.

AIM

To evaluate the role of rifabutin in the treatment of H. pylori infection.

METHODS

Bibliographical searches were performed in MEDLINE. Data on the efficacy of rifabutin-containing regimens on H. pylori eradication were combined and meta-analysed using the generic inverse variance method.

RESULTS

Rifabutin shows good in vitro activity against H. pylori. Mean H. pylori rifabutin resistance rate (calculated from 11 studies including 2982 patients) was 1.3% (95% confidence interval = 0.9-1.7%). When only studies including patients naïve to H. pylori eradication treatment were considered, this figure was even lower (0.6%). On the other hand, higher values of rifabutin resistance were calculated (1.59%) when only post-treatment patients were considered. Overall, mean H. pylori eradication rate (intention-to-treat analysis) with rifabutin-containing regimens (1008 patients) was 73% (67-79%). Respective cure rates for second-line (223 patients), third-line (342 patients) and fourth/fifth-line (95 patients) rifabutin therapies were 79% (67-92%), 66% (55-77%) and 70% (60-79%) respectively. For treating H. pylori infection, almost all studies have administered rifabutin 300 mg/day; this dose seems to be more effective than 150 mg/day. The ideal length of treatment remains unclear, but 10- to 12-day regimens are generally recommended. The mean rate of adverse effects was 22% (19-25%). Myelotoxicity is the most significant, although this complication was rare. Until now, all patients have recovered of leucopenia uneventfully in a few days, and there have been no reports of infection or other adverse outcomes related to it.

CONCLUSION

Rifabutin-containing rescue therapy constitutes an encouraging strategy after multiple (usually three) previous eradication failures with key antibiotics such as amoxicillin, clarithromycin, metronidazole, tetracycline and levofloxacin.