Abbreviations used in this paper: BPAL, bismuth compounds D proton pump inhibitor D amoxicillin D levofloxacin; CAG, Canadian Association of Gastroenterology; CI, confidence interval; GRADE, Grading of Recommendation Assessment, Development and Evaluation; ITT, intention-totreat; NNT, number needed to treat; PA, proton pump inhibitor D amoxicillin; PAC, proton pump inhibitor D amoxicillin D clarithromycin; PAL, proton pump inhibitor D amoxicillin D levofloxacin; PAM, proton pump inhibitor D amoxicillin D metronidazole; PAMC, proton pump inhibitor D amoxicillin D metronidazole D clarithromycin; PAR, PPI D amoxicillin D rifabutin; PBMT, proton pump inhibitor D bismuth compounds D metronidazole D tetracycline; PICO, Population, Intervention, Comparator, Outcomes; PMC, proton pump inhibitor D metronidazole D clarithromycin; PPI, proton pump inhibitor; RCT, randomized controlled trial; RD, risk difference.#
This article has an accompanying continuing medical education activity, also eligible for MOC credit, on page e25. Learning Objective: Upon completion of this examination, successful learners will be able to establish a treatment plan for patients with H pylori infection.

# 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
 amoxicillin  metronidazole  clarithromycin
) and traditional bismuth quadruple therapy (PPI  bismuth  metronidazole  tetracycline. 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.
A lthough the prevalence of H pylori is decreasing in some parts of the world, the infection remains present in 28% to 84% of subjects depending on the population tested. 1 Even studies in Western nations, which tend to have the lowest general prevalence,  report high proportions of infected individuals in certain communities (eg, 38%-75% of Alaskan or Canadian aboriginal populations). 2,3, H pylori is implicated in the development of and its eradication is recommended in the treatment of duodenal or gastric ulcers, early gastric cancer, and gastric mucosaassociated lymphoid tissue lymphomas (in <0.01%). 4, Treatment has been suggested for prevention of gastric cancer in high-risk individuals, 15 as well as in patients with uninvestigated 16 and functional dyspepsia, 17 given evidence that eradication of the infection leads to sustained improvements in symptoms in a proportion of patients. 10,16,17 The increasing prevalence of antibiotic-resistant strains of H pylori has led to reduced success with traditional H pylori treatments.  Proton pump inhibitor (PPI) triple therapies (a PPI plus two of the following antibiotics: clarithromycin, amoxicillin, or metronidazole) for 7 to 10 days were once standard and recommended as first-line therapy 25 but have become increasingly ineffective, with some studies reporting eradication in less than 50% of cases. 21,22, Suboptimal patient compliance may be another cause of treatment failure. 4, It has been suggested that the goal of H pylori therapy should now be eradication in !90% of treated patients. 32 This arbitrary threshold is not easily achieved, especially in real-world settings. However, the most efficacious therapies available should be used first to avoid the cost, inconvenience, and risks associated with treatment failure. Some of the more common regimens for H pylori eradication include bismuth quadruple therapy (PPI  bismuth compounds  metronidazole  tetracycline, nonbismuth quadruple therapy (concomitant
-r sequential, PPI triple therapy (PPI  amoxicillin  clarithromycin PMC, or PPI  amoxicillin  metronidazole
), and quinolonecontaining regimens (PPI  amoxicillin  levofloxacin. Definitions of these and other regimens discussed in this consensus paper are shown in Table 1, with suggested doses listed in Table 2.
The increasing prevalence of antibiotic-resistant strains and evidence of more frequent failures of triple therapies suggest the need for more effective therapies given for a longer duration (14 days instead of 10 or 7 days) than were recommended in prior consensus statements. 11,12 For this reason, as well as the existence of new therapies, the Canadian Association of Gastroenterology (CAG) and the Canadian Helicobacter Study Group determined that an update was needed. The purpose of this consensus process performed a systematic literature search of the Cochrane Register, MEDLINE, EMBASE, and CENTRAL for trials published from January 2008 to December 2013. The main focus of all literature searches was to identify data on cure rates of H pylori infection. We did not systematically search the literature before 2008 because we did not want older data, where higher eradication success rates were likely a result of lower antibiotic resistance, to confound newer data. Key search terms were Helicobacter pylori, eradication, bismuth, clarithromycin, metronidazole, amoxicillin, levofloxacin, tetracycline, and rifabutin, among others, to address each of the statements. Search strategies were limited to the English language and human studies, and further details are provided in Supplementary Appendix 1.
A formal systematic review was performed for every statement. This included a literature search and, as described in more detail in the following text, a review of the citations to identify potentially relevant articles, review of selected full-text articles to identify articles that satisfied the predefined PICO components (Population, Intervention, Comparator, Outcomes), a risk-of-bias assessment, and at least a qualitative synthesis of evidence presented formally to the panel members verbally and/or with slide presentations at the face-to-face meeting. The panel also had access to the entire text of all the selected articles should they choose to refer to it.
The literature search produced 2943 citations; after removal of duplicates, 2373 citations remained. These citations were sorted into three separate lists: (1) results enriched with randomized controlled trials (RCTs), systematic reviews/metaanalyses, and practice guidelines (1509 citations); (2) results enriched with Canadian studies (an additional 13 citations); and (3) the remaining 851 citations. Additional focused, updated searches up to June 2015 were conducted for presentation at the consensus meeting. In the absence of updated systematic reviews or meta-analyses on a specific treatment, a meta-analysis was performed for this consensus when sufficient data were available. When a recent well-done metaanalysis was found, a literature review was also performed to see if more current data altered the results and conclusions.

# Review and Assessment of Evidence
Two nonvoting methodologists (GIL and PM) assessed the quality (certainty) of evidence using the Grading of Recommendation Assessment, Development and Evaluation (GRADE) method. 33 The methodologists assessed the risk of bias (of individual studies and overall across studies), indirectness, inconsistency, imprecision, and other considerations (including publication bias) to determine the overall quality of evidence for each statement. GRADE assessments were then reviewed and agreed on by voting members of the consensus group at the meeting.
The quality of evidence for each statement was graded as high, moderate, low, or very low, as described in GRADE 33,34 and prior CAG consensus documents. 35,36 Approved product labeling from government regulatory agencies varies from country to country; although not ignored, recommendations are based on evidence from the literature and consensus discussion and may not fully reflect the product labeling for a given country.

# Consensus Process
The consensus group was composed of 8 voting members (5 participants and 3 steering committee members), including gastroenterologists, clinical epidemiologists (one of whom was not a gastroenterologist), and microbiologists from Canada, the United States, and Europe with expertise in managing H pylori infection. There was representation from a pediatric and community, nonacademic gastroenterologist (not an H pylori expert), and there was a nonvoting moderator for the meeting (Dr John K. Marshall). Although there was no primary care representative, the impact of the recommendations on primary care physicians, as well as community resources and local availability, was discussed before voting for each statement.
Before the 2-day consensus meeting was held in Toronto, Ontario, Canada, in June 2015, CAG facilitated the majority of the consensus process through the use of a web-based consensus through the web-based platform and "tagged" (selected and linked) all relevant references to a specific statement. Only one member was required to tag a reference for it to remain linked to the statement. Subsequently, the tagged references were again assessed by the steering committee; when a meta-analysis (of sufficient quality) was tagged to a statement, any tagged study that was already included in the meta-analysis was removed from that particular statement. Any studies performed after the metaanalysis remained tagged and were used to determine if the more current data altered the results or conclusions of the metaanalysis. At the end of this process, 116 papers were selected and uploaded onto the online platform. All members of the consensus group had access to complete copies of the "tagged" references. The entire consensus group then voted anonymously on their level of agreement with the specific statements using a modified Delphi process. 37,38 Two subsequent iterations of the statements that incorporated suggested changes from the group followed, after which the statements were finalized at the live meeting.
At the 2-day face-to-face meeting, the methodologists, epidemiologists, and other members of the panel who had conducted systematic reviews or meta-analyses for the conference presented, for each statement, a summary of data from existing meta-analyses from the literature as well as the systematic reviews or meta-analyses conducted for that statement. The evaluations regarding the GRADE approach for the statements were also reviewed, and all panelists discussed the findings and other issues before finalization of the phrasing for individual statements. Any PICO components that are unequivocally implied were removed from the final statements to make the message clearer to the readers. Finally, participants were asked to vote on their level of agreement for each specific statement. A statement was accepted if >75% of participants voted 4 (agree) or 5 (strongly agree) on a scale of 1 to 5 (with 1, 2, and 3 representing disagree strongly, disagree, and uncertain, respectively).
Once a statement was accepted, the participants then voted on the "strength" of the recommendation, which was accepted with a 51% vote. Per the GRADE system, the strength of each recommendation was assigned as strong ("we recommend.") or conditional ("we suggest."). The strength of the recommendation considers risk-benefit balance, patients' values and preferences, cost and resource allocation, and quality of the evidence. Therefore, it is possible for a recommendation to be classified as strong despite having low-quality evidence to support it or conditional despite the existence of high-quality evidence to support it. 39 Based on the GRADE approach, a strong recommendation indicates the statement should be applied in most cases, while a conditional recommendation signifies that clinicians ".should recognize that different choices will be appropriate for different patients and that they must help each patient to arrive at a management decision consistent with her or his values and preferences." 39 The steering committee drafted the initial manuscript, which was revised by all members of the consensus group and all authors, after which it was made available to all members of CAG for comments before submission for publication. Per CAG policy, all participants provided written disclosure of relevant potential conflicts of interest for the 24 months before the meeting, which were made available to the other group members.

# Role of the Funding Sources
CAG administered all aspects of the meeting, which was cofunded by CAG and the Canadian Helicobacter Study Group with no external funding sources.

# Recommendation Statements
The individual recommendation statements are provided and include the quality of supporting evidence as assessed by the GRADE method and the voting results; a discussion of the evidence considered for the specific statement is also presented. The quality of evidence was determined to be low for some statements, largely because of high risk of bias (most often due to lack of adequate blinding). Acknowledging the importance of quality of evidence, the consensus group also considered other factors in issuing strong rather than conditional recommendations for certain statements despite lower quality of evidence. The strength of these recommendations was driven by consequences of therapeutic failure, including the negative consequences of peptic ulcer disease, such as gastrointestinal bleeding, an increased risk of the development of gastric cancers, and an increased risk of the development of resistant strains. 20,40,41 In addition, eradication success is highest with initial therapy and decreases with subsequent rescue therapy attempts. 42,43 Hence, a treatment option may have been strongly recommended even if the evidence was not high quality to avoid the negative consequences of failure.
A summary of the recommendation statements is provided in Table 3. The most important evidence for each of the statements is summarized in Supplementary Tables 1 to 14.  4). There was In patients with H pylori infection, we recommend that the choice of first-line therapy consider regional antibiotic resistance patterns and eradication rates. GRADE: Strong recommendation; quality of evidence low. 3. In patients with H pylori infection, we recommend traditional bismuth quadruple therapy (PBMT) for 14 days as one of the options for first-line therapy. GRADE: Strong recommendation; quality of evidence moderate for efficacy and very low for duration. 4. In patients with H pylori infection, we recommend concomitant nonbismuth quadruple therapy (PAMC) for 14 days as one of the options for first-line therapy. GRADE: Strong recommendation; quality of evidence moderate for efficacy and very low for duration. 5. In patients with H pylori infection, we recommend restricting the use of PPI triple therapy (PAC or PMC for 14 days) to areas with known low clarithromycin resistance (85%). GRADE: Strong recommendation; quality of evidence moderate for efficacy of PPI triple therapy for 14 days and low for restrictions. 6. In patients with H pylori infection, we recommend against the use of levofloxacin triple therapy (PAL) as a first-line therapy. GRADE: Strong recommendation; quality of evidence very low. 7. In patients with H pylori infection, we recommend against the use of sequential nonbismuth quadruple therapy (PA followed by PMC) as a first-line therapy. GRADE: Strong recommendation; quality of evidence moderate. Prior failure 8. In patients who have previously failed to respond to H pylori eradication therapy, we recommend traditional bismuth quadruple therapy (PBMT) for 14 days as an option for subsequent therapy. GRADE: Strong recommendation; quality of evidence low. 9. In patients who have previously failed to respond to H pylori eradication therapy, we suggest levofloxacin-containing therapy for 14 days as an option for subsequent therapy. GRADE: Conditional recommendation; quality of evidence low. 10. In patients who have previously failed to respond a clarithromycin-containing H pylori eradication therapy, we recommend against the use of clarithromycin-containing regimens as subsequent therapy. GRADE: Strong recommendation; quality of evidence low. 11. In patients who have previously failed to respond to a levofloxacin-containing H pylori eradication therapy, we recommend against the use of levofloxacin-containing regimens as subsequent therapy. GRADE: Strong recommendation; quality of evidence low. 12. In patients who have previously failed to respond to H pylori eradication therapy, we recommend against the use of sequential nonbismuth quadruple therapy (PA followed by PMC) as an option for subsequent therapy. GRADE: Strong recommendation; quality of evidence very low. 13. We recommend restricting the use of rifabutin-containing regimens to cases in which at least 3 recommended options have failed.
GRADE: Strong recommendation; quality of evidence very low. Supplemental therapy 14. In patients with H pylori infection, we recommend against routinely adding probiotics to eradication therapy for the purpose of reducing adverse events. GRADE: Strong recommendation; quality of evidence very low. 15. In patients with H pylori infection, we recommend against adding probiotics to eradication therapy for the purpose of increasing eradication rates. GRADE: Strong recommendation; quality of evidence very low.
NOTE. The consensus group concluded that there was insufficient evidence to support or refute the efficacy of PAMC as a second-line option and thus was unable to recommend for or against this regimen as a rescue therapy. Similarly, the group concluded that there was insufficient evidence to make a recommendation on high-dose dual therapy with a PPI and amoxicillin. See Tables 1 and 2 for more details on regimens and dosing. NOTE. Based on data from a meta-analysis by Yuan et al. 28 Values are relative risk for H pylori persistence (95% CI); NNT (95% CI); studies (n). PAQ, PPI  amoxicillin  quinolone.

# July 2016
Toronto Consensus for H pylori Treatment no increase in discontinuations due to adverse events with increasing duration of therapy. With regard to quadruple therapies, a systematic review of cohort studies found a trend toward greater treatment success with longer durations (from 3 to 10 days) of nonbismuth quadruple therapy (PAMC) (see statement 4). 44 A 14-day optimized PAMC combination also achieved higher eradication rates compared with standard 10-day PAMC (ITT, 93% vs. 87%; P <.01); however, the optimized regimen was not only of longer duration but also included an increased PPI dose. 45 Finally, for bismuth quadruple therapy, the Cochrane meta-analysis of RCTs did not find that duration has a significant effect on therapeutic success for first-line therapy (Table 4), 28 but there are very few studies with this comparison and a trend was suggested (see statement 3). A meta-analysis performed for the consensus meeting assessed the duration of this regimen for the treatment of those who previously failed to achieve eradication. Overall, 51 RCT and cohort studies were included (see statement 8), and meta-analysis showed that the ITT eradication rate was numerically but not statistically higher with the 14-day regimen versus the 10-day regimen (78.7% vs 75.6%; P 14.33).
Other issues and discussion. The increasing prevalence of resistant strains of H pylori has led to increasing proportions of failure of traditional H pylori treatments.  In a RCT of clarithromycin-containing triple therapies, the eradication success rate of resistant strains was 35% lower than that of sensitive strains. 46 The impact was greatest among regimens of the shortest duration; the eradication success rate of sensitive versus resistant strains was 42% higher in the 7-day group, 33% higher in the 10-day group, and 22% higher in the 14-day group. Therefore, indirect evidence supports increased efficacy with longer durations of therapy in resistant strains. The differences in efficacy between therapies in the studies presented are likely underestimated, because many of the studies are older and the proportion of resistant strains has increased since they were conducted. Decisions. In light of the higher eradication rates with longer durations of therapy compared with regimens of shorter durations, the consensus group strongly recommended that all H pylori regimens (both first-line and rescue therapies) be administered for 14 days. This prolonged use of antibiotics for all patients is warranted because the increased failures with shorter regimens would result in resistant strains and less successful future treatments. It is best to achieve the maximum cure rates from the start.

# First-Line Therapy
Statement 2. In patients with H pylori infection, we recommend that the choice of first-line therapy consider regional antibiotic resistance patterns and eradication rates. GRADE: Strong recommendation; quality of evidence low. Vote: strongly agree, 100%.
Key evidence (Supplementary Table 2). Although no study directly examined the impact of tailoring first-line therapy to local antibiotic resistance patterns and eradication rates, a meta-analysis of 5 RCTs (n 14 701) found that culture-guided triple therapy resulted in a significantly lower risk of treatment failure compared with empirical standard triple therapy (ITT relative risk, 0.84; 95% CI, 0.77-0.90; P <.00001; eradication rate, 85.4% vs 71.5%). 47 Other issues and discussion. H pylori-resistant strains have become more prevalent over time. 19 Studies from the 1990s showed a low prevalence of clarithromycin resistance ranging from 1% to 8%, 18,19 which has risen to 16% to 24% in more recent studies from around the world.  Primary resistance to metronidazole appears to have remained relatively stable over time at 20% to 40%. 4,51 H pylori resistance to amoxicillin generally remains low at approximately 1% to 3%. 4,18,19,50,51 In addition, the prevalence of secondary resistance to clarithromycin and metronidazole is very high: up to 67% to 82% for clarithromycin and 52% to 77% for metronidazole. 20,40,50 RCTs confirm that the proportion of successful eradication is significantly lower in resistant compared with sensitive strains, especially with triple therapy 46, and therapy of shorter duration. 46 The increasing prevalence of clarithromycin resistance is likely the main factor contributing to the increasing failure of non-culture-guided H pylori therapies over time, especially clarithromycinbased triple therapies. 21,22 A meta-analysis of 12 studies found that success of eradication with bismuth quadruple therapy remained stable at approximately 80% in studies from 2006 to 2011 compared with those from 2000 to 2005, but the efficacy of clarithromycin-based triple therapy decreased from approximately 80% in studies from 2000 to 2005 to only 62% in more recent studies (2006-2011) (Figure 1). 22 Bismuth quadruple therapy is unaffected by clarithromycin resistance. 22,53 However, the eradication success Figure 1. Pooled successful eradication (ITT) in subgroup analysis according to year of study publication. Based on data from a meta-analysis by Venerito et al. 22 RDs are shown as proportions rather than percentages.
rate with PBMT seems to be slightly lower in metronidazoleresistant versus metronidazole-sensitive strains (92% vs. 80%; P 14.06). 53,54 In one meta-analysis of triple and quadruple regimens, the successful eradication rate was found to decrease by 0.5% for every 1% increase in the prevalence of metronidazole resistance, suggesting that when metronidazole resistance is 30%, treatment efficacy decreases by 15%. 56 Similar effects of resistance have been seen with levofloxacin triple therapy and bismuth quadruple levofloxacinbased therapy; among levofloxacin-susceptible strains, the eradication rate was 97% in both groups; however, among resistant strains, the proportion dropped to 71% with quadruple therapy and 38% with triple therapy. 52 If the susceptibility profile of a patient's infection or an estimate of it from the patient's population is known, the efficacy of a proposed regimen can be predicted.  Unfortunately, the resistance data required for these predictions is not available in most areas. Pragmatically, a combination of local experience of treatment success with different regimens and the patient's pretreatment exposure to antibiotics can also aid in the identification of the regimen most likely to succeed. 60 Decisions. Evidence suggests that culture-guided therapy is associated with higher eradication success rates 47 and that both antibiotic-resistant H pylori 18,19, and treatment failures 46, are increasing. Therefore, it is important to encourage susceptibility testing to be made available locally and performed if the patient is undergoing endoscopy. However, it is not currently clinically practical or often possible to perform susceptibility testing in all patients. Therefore, the consensus group advised that local susceptibility patterns be used as a helpful surrogate when available. Studies to determine the local prevalence of primary antibiotic resistance patterns are essential to assist clinicians in selecting the most appropriate first-line treatment for their practice. When available, the actual proportion of patients with successful eradication after receiving a specific treatment can be used to guide future treatment selection. As such, clinicians are encouraged to maintain records of the eradication rates they obtain locally with treatments. Statement 3. In patients with H pylori infection, we recommend traditional bismuth quadruple therapy (PBMT) for 14 days as one of the options for first-line therapy. GRADE: Strong recommendation; quality of evidence moderate for efficacy and very low for duration. Vote: strongly agree, 75%; agree, 25%.
Key evidence (Supplementary Table 3). Two systematic reviews of RCTs have evaluated the efficacy of first-line bismuth quadruple therapy (PBMT) compared with triple therapy (PAC). 21,22 The more recent meta-analysis of 12 RCTs found that the overall pooled eradication success rate was 77.6% with PBMT and 68.9% with PAC (risk difference 6%; 95% CI, A1% to 13%; note that the mathematical difference in the eradication success rate is not the same as the RD because the latter statistic is more appropriately weighted for the study effect size and precision of each estimate). 22 Although this analysis did not show a statistically significant difference, there was a trend toward greater eradication rates with PBMT. 22 The subgroup analysis of duration showed that 10-day quadruple therapy was more effective than 7-day triple therapy, but no differences were noted between the therapies when given for the same duration for either 7 days or 10 to 14 days. Specific analyses for 14-day PBMT were not performed. Only one study was found that directly compared 14-day durations in first-line therapy, which showed higher eradication success rates with bismuth quadruple therapy compared with triple therapy; however, this was significant only in the perprotocol analysis and not the ITT analysis. 61 In addition, antimicrobial resistance has been shown to have less impact on the success of PBMT regimens (metronidazole-sensitive vs -resistant strains, 89.4% vs 80.6%) compared with PAC regimens (clarithromycin-sensitive vs -resistant strains, 90.2% vs 22.2%). 21 Other issues and discussion. As described in statements 1 and 8, a meta-analysis of observational data conducted for the meeting to evaluate the duration of bismuth quadruple rescue therapy showed by regression analysis that the ITT eradication success rate was numerically higher with the 14-day versus the 10-day regimen, although this was not statistically different (78.7% vs 75.6%; P 14.33).
The bismuth formulations used in these studies varied considerably, with colloidal bismuth subcitrate (De-Nol) used most commonly in Europe and bismuth subsalicylate (Pepto-Bismol) used most commonly in North America; however, whether the different formulations result in a different outcome is not clear. Although usually administered 4 times a day, some studies (from China) have suggested that giving double the dose of bismuth twice daily is also effective. 62 There were no significant differences in proportions of adverse events or compliance between first-line PBMT and PAC in the meta-analyses. 21,22 However, adherence tends to be higher in clinical trials compared with real-world settings. Data show that in many therapeutic areas, adherence is negatively affected by dose frequency and regimen complexity (multiple medications, multiple doses, specific dietary or time requirements). 63 In one study, adherence to H pylori treatment was shown to decrease with increasing dose frequency and pill burden. 29 In the follow-up survey, 26% of patients reported that frequent dosing had reduced their ability to comply with a 4-drug treatment, while 22% reported that the number of pills required reduced their compliance. 29 Decisions. As described in statement 2, meta-analyses show a substantial decrease in eradication success in studies from 2006 and later compared with those conducted in 2005 and earlier; the decrease was much more pronounced with triple therapy, likely due to development of resistance (Figure 1). 21,22 This finding and the efficacy data presented in the preceding text suggest that bismuth quadruple therapy is more effective than triple therapy, with longer durations of therapy resulting in more effective eradication. However, these analyses also show that eradication success rates with 7-to 10-day regimens are suboptimal at approximately 80% (usually for 7-to 10-day regimens) and that success rates are decreasing over time. 21,22 Therefore, despite the limitations of these data, the consensus group supported the use of PBMT with the optimal duration of 14 days when given as first-line therapy. Because the proportion of eradication success decreases with subsequent rescue therapy attempts, this was voted a strong recommendation. 42,43 The consensus group suggested steps that could be taken to minimize the impact of the more complex regimen on adherence. One strategy to improve compliance with PBMT might be prescribing the PPI twice daily and the other agents 4 times a day versus prescribing a combination of dosing 4 times a day (for bismuth and tetracycline) and 3 times a day (for metronidazole) (Table 2). Having the pharmacy prepare blister packs can also help. In some countries, a 3-in-1 pill is available, which simplifies dosing for patients. 54, In patients with penicillin allergies, PBMT would be the preferred first-line option. This regimen was shown to be more effective than triple therapy (PMC) in a prospective study in patients allergic to penicillin (ITT eradication rate, 75% and 59%; P <.05). 67 Statement 4. In patients with H pylori infection, we recommend concomitant nonbismuth quadruple therapy (PAMC) for 14 days as one of the options for first-line therapy. GRADE: Strong recommendation; quality of evidence moderate for efficacy and very low for duration. Vote: strongly agree, 87.5%; agree, 12.5%.
Key evidence (Supplementary Table 4). Meta-analyses of RCTs assessing the efficacy of concomitant nonbismuth quadruple therapy (PAMC) have generally reported pooled ITT eradication success rates of approximately 90%, 44,68,69 although one meta-analysis reported 81% success with 5to 10-day regimens. 70 However, a trend toward better eradication with longer durations of treatment has been shown: 85%/88%/89%/93%/92% for 3 days/4 days/5 days/7 days/10 days, respectively. 44 An updated metaanalysis of observational data extracted from RCTs, performed for the consensus meeting, included 57 RCTs as of 2015 and found an overall ITT eradication success rate with nonbismuth concomitant quadruple therapy of 88% (95% CI, 86%-89%). 69 In subgroup analyses, concomitant therapy was more effective than triple therapy (n 14 19 RCTs; RD, 11%; 95% CI, 7%-16%; P <.00001) and more effective than sequential therapy in studies that compared the same drugs at the same dose and for the same duration (n14 14 RCTs; RD, 6%; 95% CI, 3%-9%; P <.0001) (Figure 2). 69 Concomitant therapy also performed better than sequential therapy in resistant strains (clarithromycin resistance, 92% vs 62% 55,71,72 ; metronidazole resistance, 97% vs 82%  ; dual clarithromycin and metronidazole resistance, 79% vs 47% 55,71-73. 69 Other issues and discussion. Two Spanish studies that assessed a regimen called optimized PAMC (increased PPI dose of esomeprazole 40 mg twice daily and extended duration from 10 to 14 days) found higher ITT eradication success rates compared with optimized triple therapy (PPI dose of esomeprazole 40 mg twice daily and 14-day duration) (90.4% vs 81.3%; P <.001) 74 and compared with standard concomitant therapy (93% vs 87%; P <.01). 45 Adverse events were significantly more common with the optimized PAMC therapy (w8%-15% more common), but compliance with therapy was similar between groups. 45,74 Decisions. Based on the evidence of acceptable eradication rates and the trend toward increasing efficacy with longer durations, the consensus group agreed that concomitant quadruple therapy (PAMC) for 14 days should be considered a first-line option. However, for patients allergic to penicillin, PBMT is the preferred first-line option (see statement 3).
Statement 5. In patients with H pylori infection, we recommend restricting the use of PPI triple therapy (PAC or PMC for 14 days) to areas with known low clarithromycin resistance (85%). GRADE:
Strong recommendation; quality of evidence moderate for efficacy of PPI triple therapy for 14 days and low for restrictions. Vote: strongly agree, 12.5%; agree, 75%; disagree, 12.5%.
Key evidence (Supplementary Table 5). Although metaanalyses of RCTs (mainly published before 2008) have not shown a significant difference in eradication rates with PPI triple therapies compared with bismuth and nonbismuth quadruple therapies (see statement 3), 21,22,70 eradication success rates with triple therapies have been decreasing over time (Figure 1). 21,22,75 As described with statement 2, the success of clarithromycin-based therapies is very dependent on the susceptibility profile of the organism to this antibiotic. 21,22,46, In one meta-analysis, triple therapy achieved eradication in 88% of clarithromycin-sensitive strains but in only 14% of clarithromycin-resistant strains (RD, 75%; 95% CI, 63%-87%). 22 In addition, as discussed in statement 1, a 14-day duration is associated with a superior success rate compared with shorter durations of this regimen. 27,28,76 Other issues and discussion. PAM is a PPI triple therapy that avoids the issue of clarithromycin resistance. However, it was inferior to PAC and PMC in earlier studies, 77 and therefore it was concluded that use of PAM should also be restricted to areas with demonstrated high rates of success.
Decisions. The dramatic impact of resistance on the efficacy of triple therapy reinforces the need to restrict this treatment to areas where it has demonstrated recent and ongoing high successful eradication rates (usually !90%; however, in the real-world setting, the consensus group decided >85% would be appropriate). The consensus group acknowledged that most clinicians may not know the prevalence of clarithromycin resistance in their local population (see statement 2). In such cases, given the evidence of inadequate eradication rates, they recommend that clinicians err on the side of caution and avoid PPI triple therapy containing clarithromycin (PAC, PMC) unless they have evidence of high success rates (>85%) in their community. In addition, contrary to prior recommendations, 11,12 if triple therapy is to be used at all, it should be given for 14 days. Statement 6. In patients with H pylori infection, we recommend against the use of levofloxacin triple therapy (PAL) as a first-line therapy. GRADE: Strong recommendation; quality of evidence very low. Vote: strongly agree, 87.5%; agree, 12.5%.
Key evidence (Supplementary Table 6). In RCTs, ITT eradication success rates for the 7-day and 10-day levofloxacin-containing triple therapy regimen (PAL) for first-line therapy ranged from 74% to 85%. 52, Although this regimen was significantly more effective than PAC triple therapy for the same duration, eradication rates were generally inadequate (<80% in most studies). Several studies that assessed susceptibility found dramatically lower eradication rates with PAL in levofloxacin-resistant versus levofloxacin-sensitive strains (37.5% vs 97.3% 52 and 50.0% vs 84.4% 81.
Other issues and discussion. Levofloxacin is widely used for other types of infections; as such, there is a high prevalence of background resistance to this and other quinolones (primary resistance, 6%-36% 48,52, ; secondary resistance, 18%-63%). 83,84 There is also crossresistance with other quinolones. 86 Levofloxacin resistance among respiratory, urinary, and other pathogens is highly correlated with use of fluoroquinolones,  and therefore its use should be limited.
Decisions. Based on the unacceptably low eradication rates of PAL for first-line therapy and the high prevalence of levofloxacin resistance, the consensus group agreed that other regimens, particularly bismuth quadruple therapy (PBMT) and concomitant nonbismuth quadruple therapy (PAMC), are preferred in this setting. Statement 7. In patients with H pylori infection, we recommend against the use of sequential nonbismuth quadruple therapy (PA followed by PMC) as a first-line therapy. GRADE: Strong recommendation; quality of evidence moderate. Vote: strongly agree, 50%; agree, 37.5%; uncertain 12.5%.
Key evidence (Supplementary Table 7). Meta-analyses of early studies (up to 2009) with sequential therapy showed promising results, with eradication rates consistently higher than 90%.  Several more recent meta-analyses have shown that 10-day sequential therapy is not superior to 14day triple therapy, 70,94,95 bismuth quadruple therapy, 70 and concomitant nonbismuth quadruple therapy. 70,96,97 The updated meta-analysis of studies performed for this consensus meeting (as of 2015) included 14 RCTs comparing sequential and concomitant nonbismuth quadruple therapy using the same drugs at the same dose and for the same duration (see statement 4). 69 In this analysis, concomitant therapy was significantly more effective than sequential therapy (ITT eradication rate, 85.7% vs 79.7%; RD, 6%; 95% CI, 3%-9%; P <.0001) (Figure 2). 69 Other issues and discussion. Analyses of studies in patients with resistant strains found higher eradication rates with concomitant therapy versus sequential therapy among resistant strains (clarithromycin resistance, 92% vs 62% 55,71,72 ; metronidazole resistance, 97% vs 82%  ; and dual clarithromycin and metronidazole resistance, 79% vs 47% 55,71-73. 69 Decisions. The consensus group concluded these data strongly suggest that sequential therapy is inferior to concomitant therapy, with current successful eradication rates decreasing to <80% in more recent studies. 69,98 Therefore, nonbismuth quadruple therapy should be administered via a concomitant rather than sequential regimen.
Prior Failure Statement 8. In patients who have previously failed to respond to H pylori eradication therapy, we recommend traditional bismuth quadruple therapy (PBMT) for 14 days as an option for subsequent therapy. GRADE: Strong recommendation; quality of evidence low. Vote: strongly agree, 62.5%; agree, 37.5%.
Key evidence (Supplementary Table 8). A meta-analysis of data from 38 RCTs assessing bismuth quadruple therapy (PBMT) after failure of standard triple therapy (PAC) reported an eradication success rate of 78% (95% CI, 75%-81%). 99 There was a trend toward higher eradication rates with longer duration of therapy (7-day regimen, 76%; 10day regimen, 77%; 14-day regimen, 82%).
A meta-analysis of RCTs and cohort studies was conducted for the meeting to assess the optimal duration of bismuth quadruple therapy as rescue therapy. Overall, 51 studies were included. No direct head-to-head studies comparing 10-and 14-day durations were found, but metaregression showed that eradication rates using ITT analyses were numerically higher (although not statistically significant) with the 14-day regimen versus the 10-day regimen (78.7% vs 75.6%; P 14.33).
There is little evidence for PBMT as rescue therapy after regimens other than standard triple therapy. In a small Korean cohort study (n 14 45), third-line bismuth quadruple therapy after failure of second-line quadruple therapy had an ITT eradication rate of 66.7%. 42 In a Canadian study, PBMT rescue therapy after 1 to 5 prior treatment failures had an ITT eradication rate of 84%; however, this was much lower in patients previously exposed to bismuth and tetracycline compared with patients without exposure (55% vs 90%; RD, 35%; 95% CI, 10%-62%; P <.01). 43 Other issues and discussion. The consensus group discussed different strategies to potentially improve or optimize bismuth quadruple therapy for use in patients who previously failed to respond to treatment, such as using more potent acid inhibition or higher doses of metronidazole.
The meta-analysis of 51 studies of PBMT rescue therapy that was conducted for the meeting found no direct head-to-head studies comparing low-dose versus highdose PPI therapy or twice-daily versus more frequent dosing. However, the data allowed between-study comparisons for the dose of esomeprazole (20 mg twice daily in 9 studies and 40 mg twice daily in 6 studies). Metaregression models adjusting for duration did suggest that regimens containing esomeprazole 40 mg twice daily were more effective than regimens containing esomeprazole 20 mg twice daily (P 14.005).
A focused literature search was conducted for studies that assessed the role of the dose of metronidazole in eradication regimens. Metronidazole resistance has been shown in meta-analyses to be a predictor of failure of treatment with metronidazole-containing regimens. 26,56,100 In one meta-analysis of various regimens, metronidazole resistance reduced effectiveness by an average of 37.7% (95% CI, 29.6%-45.7%). 26,32,101,102 Increasing the dose and duration of metronidazole may at least partially overcome metronidazole resistance. 32 Some data from triple therapy studies support the use of a higher dose of metronidazole. 103,104 In the HOMER study, the eradication success rates for metronidazole-resistant strains according to dose of metronidazole in a PAM regimen were 54% with 800 mg/day, 50% with 1200 mg/day, and 75% with 1600 mg/day, although in this study the dose of amoxicillin also varied from 1.5 to 2 g/day. 103 Similarly, a comparison of doses of metronidazole in a BMT regimen showed eradication of resistant strains in 64.2% of cases with 750 mg/day compared with 39% to 40% with 375 mg/day. 104 Decisions. The consensus group concluded that for patients who have previously failed to respond to H pylori eradication therapy, traditional bismuth quadruple therapy (PBMT) for 14 days is likely one of the more effective options for rescue therapy. However, more evidence is needed to determine whether PBMT is superior to other alternatives in the second-line setting. With the prevalence of metronidazole resistance reported at 20% to 77%, 4,40,51 the consensus group recommended a dose of metronidazole in the bismuth quadruple therapy regimen of at least 1500 mg/day (maximum of 2000 mg/day) (Table 2).
Because existing data on the efficacy of PBMT as rescue therapy come primarily from studies conducted in patients who previously failed to respond to a standard triple therapy regimen, there is some controversy as to whether PBMT can be used to re-treat patients after failure of the same regimen. Some members of the consensus group advocated against repeating this regimen, whereas others supported a role for repeat PBMT, perhaps with a higher dose of metronidazole and/or a PPI in certain cases in which options are very limited (eg, cases in which the clinician wants an alternative to a rifabutin combination after the patient has failed to respond to PBMT and PAL).
Statement 9. In patients who have previously failed to respond to H pylori eradication therapy, we suggest levofloxacin-containing therapy for 14 days as an option for subsequent therapy. GRADE: Conditional recommendation; quality of evidence low. Vote: strongly agree, 12.5%; agree, 87.5%.
Key evidence (Supplementary Table 9). A meta-analysis of 5 studies assessed PAL after failure of sequential nonbismuth quadruple therapy and yielded an overall eradication rate of 81% (95% CI, 71%-91%). 99 Another meta-analysis reported an eradication success rate with PAL of 81% after sequential (6 studies) and 78% after concomitant (3 studies) nonbismuth quadruple therapy. 105 Meta-analyses of studies comparing PAL and PBMT as second-line therapy showed no significant differences in overall eradication rates (77%-79% with PAL vs 67%-69% with PBMT). 99,106 One RCT found that 14-day PAL was as effective as 14-day PBMT in patients who failed to respond to 7-day triple therapy (ITT eradication rates of 86.3% and 86%, respectively). 107 However, a recent real-world study showed superior performance of PBMT over PAL in secondto sixth-line rescue therapy (ITT, 84% vs 61%; RD, 24%. 43 Eradication rates were significantly higher (88.7%; 95% CI, 56.1%-100%; P <.05) with 10-day compared with 7day levofloxacin-containing regimens (70.6%; 95% CI, 40.2%-99.1%). 106 Other issues and discussion. An RCT showed that adding bismuth to a 14-day, first-line PAL (BPAL) regimen only marginally improved ITT eradication rates overall (87.5%  vs 82.7% ; P 14.39), but eradication rates were much higher among levofloxacin-resistant strains (70.6% vs 37.5%). 52 After prior treatment failure (including both standard triple and nonbismuth quadruple therapies), BPAL had an ITT eradication success rate of 90% (95% CI, 86%-94%) in a prospective cohort study. 108 Decisions. The consensus group agreed that for patients who have previously failed to respond to H pylori eradication therapy, levofloxacin-containing therapy (usually PAL) is an option. However, in light of evidence of higher eradication rates with longer treatment durations, 106 the consensus group recommended a 14-day regimen. Statement 10. In patients who have previously failed to respond to clarithromycin-containing H pylori eradication therapy, we recommend against the use of clarithromycin-containing regimens as subsequent therapy. GRADE: Strong recommendation; quality of evidence low. Vote: strongly agree, 100%.
Key evidence (Supplementary Table 10). As discussed with statements 2 and 5, the efficacy of clarithromycincontaining regimens is highly affected by clarithromycin resistance. 19,22,46, More importantly, the prevalence of secondary resistance is very high (up to 70% in some series). 20,40 Decisions. As a result of resistance concerns, the consensus group recommended against reuse of clarithromycin in patients who have already failed to respond to a clarithromycin-containing regimen. Statement 11. In patients who have previously failed to respond to a levofloxacin-containing H pylori eradication therapy, we recommend against the use of levofloxacin-containing regimens as subsequent therapy. GRADE: Strong recommendation; quality of evidence low. Vote: strongly agree, 62.5%; agree, 37.5%.
Key evidence (Supplementary Table 11). As discussed in statement 6, the efficacy of levofloxacin-containing regimens is highly affected by levofloxacin resistance. 52,81 Studies have shown that the prevalence of secondary levofloxacin resistance is very high (up to 63% in some series). 83,84 Decisions. As a result of resistance concerns, the consensus group recommended against reusing levofloxacin in patients who have already failed to respond to a levofloxacin-containing regimen. Previous quinolone use is also associated with levofloxacin-resistant H pylori and would be expected to reduce the therapeutic success of this agent. Statement 12. In patients who have previously failed to respond to H pylori eradication therapy, we recommend against the use of sequential nonbismuth quadruple therapy (PA followed by PMC) as an option for subsequent therapy. GRADE: Strong recommendation; quality of evidence very low. Vote: strongly agree, 50%; agree, 50%.
Key evidence (Supplementary Table 12). Cohort data have suggested that sequential nonbismuth quadruple therapy can be effective after failure of previous eradication therapy, but data are from a small number of patients ( 42patients in total) and low quality. 109,110 As discussed in statement 7, eradication success rates with this regimen were low (<80%) and inferior to concomitant administration when used in the first-line setting (Figure 2). 69 In addition, this strategy was associated with very low eradication of clarithromycin and dual clarithromycin and metronidazole resistant strains (62% and 47%). 69 Decisions. The consensus group recommended that sequential nonbismuth quadruple therapy not be used as rescue therapy, because it is less efficacious than other therapies. Statement 13. We recommend restricting the use of rifabutin-containing regimens to cases in which at least 3 recommended options have failed. GRADE:
Strong recommendation; quality of evidence very low. Vote: strongly agree, 62.5%; agree, 37.5%.
Key evidence (Supplementary Table 13). A systematic review of 21 studies assessing rescue therapy with rifabutin-containing regimens found that the overall ITT eradication success rate was 73% (95% CI, 67%-79%). 111 The success rate was 79% for second-line regimens and 66% to 70% for third-line or greater regimens. The prevalence of resistance was low at 1.3%. Rifabutin triple therapy for 10 days was shown to be effective in approximately onehalf of patients when used as fourth-line rescue therapy in a cohort of 190 patients, with an ITT eradication rate of 52% (95% CI, 45%-59%). 112,113 Other issues and discussion. The most commonly studied rifabutin-containing regimen is PPI  amoxicillin  rifabutin ; current evidence suggests that 10 days may be more effective than 7 days, but no additional benefit has been shown with 14 days, which may increase the side effect burden. 111,114 For this reason, this is the only regimen for which a duration of therapy of 10 days may be suggested; however, this suggestion is based on a small number of patients who were treated. Rifabutin-containing regimens should be reserved for patients with multiple treatment failures. Because eradication in the rescue setting is low, there are concerns about adverse events, especially myelotoxicity, and cost is also an issue. In addition, although the prevalence of resistance is low, there are theoretical concerns that overuse may increase the prevalence of rifabutin-resistant mycobacteria in the community, for which this agent is currently very important. 111 Decisions. The consensus group agreed that rifabutincontaining regimens may be useful in the rescue setting but appear to be less safe than other regimens and should be reserved for patients with multiple previous failures (eg, PBMT, PAMC, and PAL).
Other statements/comments. PAMC as rescue therapy. The consensus group concluded that there was insufficient evidence to support or refute the efficacy of PAMC as a second-line option and thus was unable to recommend for or against this regimen as a rescue therapy. In a small Japanese study, the ITT eradication rate with PAMC after failure of PAC triple therapy was 88.5%, compared with 82.7% with PAM. 115 No data were found assessing the use of this regimen after failure of bismuth quadruple therapy.
The role of acid suppression. Acid suppression plays an important role in eradication of H pylori infection. Successful eradication has been shown to be closely related to the degree of acid inhibition, with a cohort study using triple therapy (PAC) showing a significantly higher mean gastric pH in patients with versus without successful eradication (6.4 vs 5.2; P 14.013). 116 It has been suggested that achieving more potent acid inhibition can improve treatment success. Meta-analyses of RCTs have shown higher eradication rates with triple therapy using a standard-dose PPI twice daily versus once daily (13 studies; 83.9% vs 77.7%; P <.01) 117 and with a high-dose (eg, esomeprazole 40 mg twice daily) versus standard-dose PPI (eg, esomeprazole 20 mg twice daily) (6 studies; 82% vs 74%; P 14.03). 118 In addition, a meta-analysis of 35 studies showed higher eradication rates with esomeprazole (82.3% vs 77.6%; odds ratio, 1.32; 95% CI, 1.01-1.73) and rabeprazole (80.5% vs 76.2%; odds ratio, 1.21; 95% CI, 1.02-1.42) compared with first-generation PPIs (omeprazole, lansoprazole, pantoprazole). 119 Another potential method to improve acid inhibition would be to use newer, more potent antisecretory agents. Potassium-competitive acid blockers inhibit gastric H  / K  -adenosine triphosphatase in a K  competitive but reversible manner and thus do not require prior proton pump activation to achieve their antisecretory effect. 120,121 One of these agents, vonoprazan, was recently approved in Japan for a number of gastrointestinal diseases, including eradication of H pylori infection. 121 Data suggest that the pH 4 holding time with this drug is equivalent to esomeprazole 20 mg 4 times daily. 122,123 Superior clinical efficacy of this more potent acid suppressant in triple therapy regimens has been shown in first-line and second-line settings. 124 For example, vonoprazan-based triple therapy with amoxicillin and clarithromycin had greater eradication success rates (92.6% vs 75.9%; P <.0001) than the same lansoprazole-based treatment due to the difference in eradication of clarithromycin-resistant cases (82.0% vs 40.0%; P <.0001), although treatment success in the presence of clarithromycin resistance is still far from desirable. 124 High-dose dual therapy. Further evidence for increased efficacy with greater acid suppression comes from a study of high-dose PPI dual therapy. 50 Despite the recognized inadequacy of standard-dose PPI dual therapy, 125 a large RCT reported significantly higher ITT eradication rates with high-dose PPI dual therapy (amoxicillin 750 mg 4 times a day and rabeprazole 20 mg 4 times a day for 14 days; 95.3%) as first-line treatment compared with either 10-day sequential (85.3%) or 7-day standard triple therapy (80.7%) and as second-line treatment (89.3%) compared with sequential (51.8%) but not levofloxacinbased triple therapy (78.6%). 50 It is unknown how this regimen would compare with PBMT. This regimen may prove to be advantageous given the low prevalence of amoxicillin resistance, but the consensus group felt that more evidence was needed (eg, compared with 14-day PBMT or PAMC first-line therapy, compared with PBMT in rescue therapy and in other countries) before a statement on this therapy could be developed. However, highdose dual PPI therapy for 14 days may be an option when both dual metronidazole/clarithromycin resistance and levofloxacin resistance are suspected, such as in a patient with multiple previous failures to respond to therapy.

# Supplemental Therapy
Statement 14. In patients with H pylori infection, we recommend against routinely adding probiotics to eradication therapy for the purpose of reducing adverse events. GRADE: Strong recommendation; quality of evidence very low. Vote: strongly agree, 87.5%; agree, 12.5%.
Statement 15. In patients with H pylori infection, we recommend against adding probiotics to eradication therapy for the purpose of increasing eradication rates. GRADE: Strong recommendation; quality of evidence very low. Vote: strongly agree, 62.5%; agree, 37.5%.
Key evidence (Supplementary Table 14). A metaanalysis of 10 trials concluded that Lactobacilluscontaining and Bifidobacterium-containing probiotic preparations during H pylori eradication therapy may have beneficial effects on eradication rate and incidence of total side effects. 126 However, this analysis was rated low-quality evidence due to serious limitations, inconsistency, and indirectness (the majority of trials assessed the impact of probiotic supplementation when added to triple rather than quadruple therapy). Two RCTs have reported no improvement in eradication rates with the addition of probiotics to quadruple therapy in adults. 127,128 When added to sequential nonbismuth quadruple therapy, there was no significant impact on eradication rates; however, side effects and compliance were improved compared with placebo. 127 When added to bismuth quadruple therapy, a multi-strain probiotic compound showed no beneficial effects on efficacy (ITT eradication rate, 76.6% vs 81.1%; P 14.029) or overall tolerability (P 14.851) compared with placebo. 128 There was a significant reduction in diarrhea but an increase in abdominal pain.
Other issues and discussion. Although some studies suggest possible beneficial effects, these results are inconsistent across studies and there are a number of concerns with use of probiotics. 129 Formulations are not standardized and contain different bacterial strains in different combinations and at different concentrations; therefore, studies are needed to determine which, if any, specific formulations may actually have beneficial effects. Use of probiotics also increases the cost and complexity of an already complex treatment regimen.
Decisions. The consensus group concluded that the evidence does not convincingly show that probiotics will increase the efficacy of the recommended eradication therapies and they should not be used for this purpose. In contrast, although not recommended routinely for the prevention of adverse events, they may be potentially useful, and unlikely harmful, in certain high-risk cases to prevent diarrhea or Clostridium difficile infection.

# Future Directions
The lack of availability of data on local susceptibility patterns and eradication success rates was identified as a knowledge gap that has a major impact on the choice of therapy and hence best management. Periodic susceptibility testing should be considered by health authorities, and clinicians should be encouraged to record their successes. These data should be published or presented at conferences to help monitor susceptibility on an ongoing basis.
There is a need for well-conducted, head-to-head RCTs on the efficacy of concomitant nonbismuth therapy versus PBMT as first-line treatment, as well as studies on 10-day versus 14-day regimens. In addition, more data are needed on the efficacy of rescue therapies after failure of concomitant or PBMT first-line treatment.
As discussed in statement 8, there continues to be a need to determine the optimal doses of drugs included in the recommended regimens, including the effects of various doses of metronidazole (500 mg 3 times daily vs 500 mg 4 times a day) for PBMT. The role of more potent acid suppression through higher or more frequent doses, or the use of newer antisecretory agents such as vonoprazan, requires further study.
The increasing prevalence of resistance and increasing rates of failure of current therapies emphasize the need to continue developing and evaluating new regimens. Moxifloxacin-containing triple therapies have been studied in some parts of the world.  Several meta-analyses of RCTs have reported that this regimen is better tolerated than bismuth quadruple therapy and is as effective in the first-line setting 130 and more effective in the second-line setting. 130,131 However, moxifloxacin is affected by the same high prevalence of fluoroquinolone resistance as levofloxacin (see statement 6). Bismuth quadruple therapy with a PPI, amoxicillin, and clarithromycin (PBAC)  or levofloxacin (BPAL; see statement 9) may be an effective alternative to PBMT. 52,108 Eradication success rates with PBAC have been widely variable, ranging from 55% to 96% in RCTs.  In addition, this regimen will likely be affected by clarithromycin resistance.
Further study on high-dose PPI dual therapy (amoxicillin 750 mg 4 times a day and rabeprazole 20 mg 4 times a day for 14 days) 50 and other high-dose dual regimens is required before they can be recommended.
In certain countries, some agents are not available; therefore, alternative regimens may be required for treatment failure. For example, if bismuth and levofloxacin are not available, high-dose PPI dual therapy or PAM can be considered. Further studies on these and other alternatives are required for those who fail to respond to treatment.

# Limitations of the Consensus
There are some limitations of this consensus that should be mentioned. It would have been ideal if the consensus panel also included primary care physicians, patients, or other stakeholders, although their potential viewpoints were discussed at the face-to-face meeting before every vote. In addition, it was decided not to search for data before 2008 to avoid confounding of data from earlier studies that had higher eradication success rates likely as a result of lower antibiotic resistance. However, this cutoff can be viewed as a shortcoming, especially in the rare instance when no new data were available. Older studies and meta-analyses were used as a discussion point when presenting newer studies and newer meta-analyses, because we did not want to completely ignore older data. The older data were only used in decision making if newer data did not exist for that particular statement. We believe this approach was valid because it puts more emphasis on more recent data while not ignoring data published before 2008. Finally, the systematic evaluation of evidence relied on studies in which the populations had variable percentages of antibiotic resistance. This would affect the success rates of the different regimens and conclusions may not be generalizable to specific practice populations. 57 Similarly, different studies may have used different doses, dosing intervals, and relationships to meals that are not taken into account when combining results from different studies. Some of these factors may also play a role in determining outcome and have not been addressed by this consensus.
Based on evidence of higher eradication rates with regimens of longer duration and increasing failure of shorter treatment durations, the consensus group strongly recommended that all H pylori eradication regimens be given for 14 days. Recommended first-line strategies include Figure 3. Algorithm for eradication therapies for first-line and rescue treatments. Some members of the consensus group advocated against the repeat use of PBMT, whereas others suggested it may be useful to reserve rifabutin for fourth-line use (see statement 8). Optimized refers to using a higher dose of PPI or metronidazole. See Tables 1 and 2 for more details on regimens and dosing.
traditional quadruple bismuth therapy (PBMT), concomitant nonbismuth quadruple therapy (PAMC), and the restricted use of PPI triple therapy (PAC or PMC) to regions with known low clarithromycin resistance or high eradication success rates (Table 1 and Figure 3). Levofloxacin triple therapy (PAL) and sequential nonbismuth quadruple therapy (PA followed by PMC) were not recommended for firstline treatment.
Potential strategies for subsequent therapy for patients who fail to respond treatment are shown in Figure 3. The choice of second-line treatment depends on previous antibiotic exposure. If there is no previous metronidazole exposure, PBMT and levofloxacin-containing therapies are both options. If the patient was previously exposed to metronidazole, PAL is the preferred second-line option. If PAL has failed, then PBMT is the next option even if previously exposed to metronidazole. An optimized PBMT with higher-dose PPI and metronidazole 500 mg 4 times a day could be considered an option if the patient has previously failed to respond to regular PBMT and PAL, especially if one wanted to avoid rifabutin. However, there is not a large body of evidence for this, and some members of the group argued that repeating PBMT would not be useful. The use of rifabutin-containing regimens should be restricted to patients who have failed to respond to at least 3 prior options. Regarding nonbismuth quadruple therapy, there were insufficient data to make a recommendation regarding concomitant PAMC as rescue therapy, but sequential therapy (PA followed by PMC) was not recommended.  Mainly due to lack of blinding. c Hybrid regimen was omeprazole 40 mg and amoxicillin 1 g twice daily for 14 days plus clarithromycin 500 mg and nitroimidazole 500 mg twice daily for the final 7 days. The longer regimen also included a higher PPI dose. Mainly due to lack of blinding. c Calculated from unweighted means, but given that the weights of the included studies were very similar, it is likely that weighted estimates would produce similar results.  The comparisons were between studies, not within study.