Which Therapy for Helicobacter pylori Infection?

Impact of previous metronidazole exposure on metronidazole-based second-line quadruple therapy for Helicobacter pylori infection

BACKGROUND/AIMS

The negative effects on the eradication success of Helicobacter pylori infection after previous exposure to macrolides, including clarithromycin on clarithromycin-based first-line therapy have been demonstrated. However, whether this is true for metronidazole-based second-line quadruple therapy remains unclear. We investigated the relationship between past administration of metronidazole and the failure of metronidazole-based second-line quadruple therapy in patients with H. pylori infection.

METHODS

Patients over 20 years of age who were diagnosed with H. pylori infection between January 1998 and March 2016 were enrolled in this study. The relationship between the clinical parameters and the results of a C13-urea breath test after metronidazole-based second-line quadruple therapy was analyzed in patients for whom clarithromycin-based triple therapy failed to eradicate H. pylori.

RESULTS

The H. pylori eradication failure rate was significantly higher in patients with a history of metronidazole use than in patients without a history of metronidazole use (p = 0.011). Multivariable analysis showed that the odds ratio of previous metronidazole use for eradication failure was 3.468 (95% confidence interval, 1.391 to 8.649; p = 0.008). In the subgroup analysis of patients with a history of metronidazole use, the duration of metronidazole use and interval between its use and eradication therapy did not significantly affect H. pylori eradication failure.

CONCLUSION

Previous exposure to metronidazole was a significant risk factor for treatment failure of metronidazole-based second-line quadruple therapy; therefore, this should be considered when establishing a treatment strategy for patients with H. pylori infection.

Helicobacter pylori: A Review of Current Diagnostic and Management Strategies

As one of the most prevalent infections globally, Helicobacter pylori (H. pylori) continues to present diagnostic and therapeutic challenges for clinicians worldwide. Diagnostically, the "test-and-treat" strategy is the recommended approach for healthcare practitioners when managing this potentially curable disease. The choice of testing method should be based on several factors including patient age, presenting symptoms, and medication use, as well as test reliability, availability, and cost. With rising antibiotic resistance, particularly of macrolides, care must be taken to ensure that therapy is selected based on regional resistance patterns and prior antibiotic exposure. In the USA, macrolide antibiotic resistance rates in some areas have reached or exceeded a generally accepted threshold, such that clarithromycin triple therapy may no longer be an appropriate first-line empiric treatment. Instead, bismuth quadruple therapy should be considered, while levofloxacin-based or alternative macrolide-containing therapies are also options. Once treated, it is essential to test for eradication as untreated H. pylori is associated with serious complications including peptic ulcer disease, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. This review article aims to consolidate current knowledge of H. pylori infection with a particular emphasis on diagnostic and treatment strategies.

rdxA, frxA, and efflux pump in metronidazole-resistant Helicobacter pylori: Their relation to clinical outcomes

BACKGROUND AND AIM

rdxA and frxA mutations and enhancement of efflux pump have been suggested as the cause of metronidazole resistance in Helicobacter pylori. This study was performed to investigate the resistance mechanisms related to clinical eradication outcome, and to examine direct involvement of hefA in metronidazole-resistant isolates with intact rdxA and frxA.

METHODS

A total of 53 H. pylori-positive patients who were treated with metronidazole-containing sequential or quadruple therapy from 2011 to 2015 were enrolled. The metronidazole susceptibility of H. pylori isolates was examined by agar dilution test. Mutations in rdxA and frxA, were analyzed with DNA sequencing, and impact of hefA on metronidazole resistance was examined with quantitative real-time reverse transcription polymerase chain reaction, knockout and genetic complementation test for hefA.

RESULTS

Seven mutation types of rdxA and/or frxA were found in H. pylori isolated from non-eradicated subjects. rdxA mutation was associated with eradication failure (P = 0.002), and nonsense mutation in rdxA reduced eradication efficacy (P = 0.009). hefA expression was significantly higher in resistant isolates (P < 0.001), especially in rdxA(-)frxA(-) as compared to rdxA(+)frxA(+) (P = 0.027). Resistant isolates with no mutation in rdxA and frxA became susceptible after hefA knockout. Genetic complementation for hefA recovered metronidazole resistance in all of three hefA knockout mutants.

CONCLUSIONS

These results suggest that rdxA mutations play a critical role in metronidazole resistance as well as the outcomes of eradication therapy. In addition, hefA seems to be directly involved in metronidazole resistance, which explains the resistance in clinical isolates with intact rdxA and frxA.

High primary antibiotic resistance of Helicobacter Pylori strains isolated from dyspeptic patients: A prevalence cross-sectional study in Spain

BACKGROUND

The rate of H. pylori resistance to different antibiotics is increasing and determines the selection of eradication therapy. The aim of this study was to determine the resistance patterns of H. pylori strains in our area.

METHODS

Biopsies from gastric corpus for microbiological culture and antibiotic resistance were obtained in patients undergoing upper gastrointestinal endoscopy for dyspepsia. Selective Agar Pylori for isolation of the bacteria and Agar Mueller-Hinton supplemented with blood to test the sensitivity to antibiotics were used. Presence of H. pylori was confirmed using direct observation with phase-contrast microscopy and/or smears stained with acridine orange. In vitro bacterial susceptibility to amoxicillin, clarithromycin, rifampicin, tetracycline, metronidazole, and levofloxacin was tested using diffusion MIC test strips. Minimum inhibitory concentration values were determined based on the 6th version of the EUCAST (European Committee on Antimicrobial Susceptibility Testing) Clinical Breakpoint (2016).

RESULTS

Two hundred and seventeen patients were included (58.1% female, median age 64 years, range 25-92). H. pylori was identified in 108 patients (49.8%); culture and antibiogram were completed in 77 of them (71.3% of H. pylori-positive patients). The resistance rates were as follows: levofloxacin 38.7%, rifampicin 33.3%, metronidazole 27% and clarithromycin 22.4%. No case of amoxicillin or tetracycline resistance was identified. Dual clarithromycin-metronidazole resistance was observed in 10% of strains, whereas multiple drug-resistant was observed in 14.2%.

CONCLUSIONS

Resistance rate of H. pylori to antibiotics is high in the northwest of Spain. The high resistance to levofloxacin and clarithromycin advises against their wide empirical use of these antibiotics in eradication regimens.

Effectiveness of 7-Day and 14-Day Moxifloxacin-Dexlansoprazole Based Triple Therapy and Probiotic Supplement for Helicobacter Pylori Eradication in Thai Patients with Non-Ulcer Dyspepsia: A Double-Blind Randomized Placebo-Controlled Study

Background: Helicobacter pylori (H. pylori) is important cause of peptic ulcer and gastric cancer. Moxifloxacin is effective antibiotic for treatment for H. pylori. However, there were limited studies as first line therapy. Probiotics had been shown to decrease therapy-related side-effect and increase eradication rate. Aim of this study was to evaluate the efficacy of moxifloxacin-dexlansoprazole based triple therapy with probiotic for H. pylori treatment in Thailand. Methods: Patients with H. pylori infected gastritis were randomized to receive 7- or 14-day moxifloxacin-dexlansoprazole based triple therapy with probiotic or placebo. Regimen consisted of 60 mg dexlansoprazole twice daily, 400mg moxifloxacin once daily, 1g clarithromycin MR once daily. Probiotic used in this study was 282.5mg Saccharomyces boulardii (S. boulardii) in capsule prescribed twice daily. CYP2C19 genotyping, antibiotic susceptibility tests, and CagA genotyping were also done. Successful eradication was defined as a negative 13C-urea breath test at least 4 weeks after treatment. Results: Total of 108 subjects was enrolled (27 each to 7-and 14-day regimens with probiotic or placebo). Antibiotic susceptibility tests showed 29% fluoroquinolone, 19% metronidazole and 4% clarithromycin resistance. CYP2C19 genotyping demonstrated 43%, 47% and 11% were rapid, intermediate and poor metabolizers, respectively. CagA genes were positive in all patients. Eradication rates of 7-day and 14-day regimens with probiotic were 100%, and 93% respectively. There were no significant differences between eradication rate of 7-day and 14-day regimen with or without probiotics. Regarding side-effects, incidence of nausea, abdominal discomfort, bitter taste, and diarrhea were significantly lower in regimen with probiotic group compared with placebo(7.4%vs. 22.2%; p=0.028, 0.00%vs.14.8%; p=0.003, 35.2%vs.70.4%; p=0.0002, and 0.00%vs.9.3%; p=0.028, respectively). Conclusions: 7-day moxifloxacindexlansoprazole therapy plus S. boulardii provide an reliable cure rate of H. pylori in non-ulcer dyspeptic patients in Thailand, independent of CYP2C19 genotype. Probiotic adding also decreased side effects during the treatment.

Optimization strategies aimed to increase the efficacy of H. pylori eradication therapies

BACKGROUND

As with any other infectious disease, we should aim for treatments offering ≥90% Helicobacter pylori eradication rates in clinical practice.

AIM

To summarize optimization strategies aimed to increase the efficacy of H. pylori eradication therapies.

METHODS

A systematic bibliographic search (in PubMed up to August 2016) was designed to identify studies investigating optimization strategies aimed to increase the efficacy of H. pylori eradication therapies.

RESULTS

The most direct way to optimize a treatment is using higher doses of drugs unless it has been shown that lower doses are equally effective. Similarly, prescriptions should use 14-day duration unless a shorter scheme has been shown locally to be equally effective. Double-dose proton-pump inhibitor therapy is recommended for triple therapy and may probably increase the efficacy of nonbismuth concomitant regimen as well. The efficacy of triple therapies in the presence of resistance can be significantly improved by the addition of bismuth salts, which offer an additive effect in combination with antibiotics. Overall, probiotics seem to reduce antibiotic side effects, but the increase in eradication rates is not so evident; therefore, they cannot be generally recommended for clinical practice yet.

CONCLUSIONS

Using potent acid inhibition and/or higher antibiotic doses-especially by increasing the number of daily intakes-and lengthening treatments up to 14 days improves efficacy in most regimens and should be generally recommended. Triple therapies can be efficiently improved by the addition of bismuth salts, turning them into quadruple therapies. Finally, some treatments will require a combination of optimization strategies to significantly improve results.

First-line therapies for Helicobacter pylori eradication: a critical reappraisal of updated guidelines

Helicobacter pylori (H. pylori) treatment remains a challenge for the clinician, as no available therapy is able to cure the infection in all treated patients. In the last two decades, several antibiotic combinations have been proposed, including triple therapies, bismuth-free therapies (sequential, concomitant, hybrid regimens), and bismuth-based quadruple therapy. Some national and international guidelines on H. pylori management have recently been updated, recommending or discouraging the use of each of these therapeutic approaches, based mainly on the presumed pattern of primary antibiotic resistance in different geographic areas. We examined the recommendations on first-line therapies in the most recently updated guidelines worldwide, taking into account other data affecting the efficacy of a therapy regimen beyond the primary resistance pattern. Although several guidelines highlighted that the results achieved by an eradication therapy are population-specific and not directly transferable, it emerged that some therapy regimens are recommended or discouraged with no mention of the vital need for national data.

New opportunities for the prevention of gastric cancer

The approvals and provisions of the Management of Helicobacter pylori infection-the Maastricht V/ Florence Consensus Report and those of the Kyoto Global Consensus Conference on H. pylori-associated gastritis, concerning with the primary and secondary prevention of gastric cancer (GC), unambiguously suggest that H. pylori infection is the most important risk factor of GC. Accordingly, the basis for the primary and secondary prevention of GC is the optimization of H. pylori eradication therapy. The clear direct relationship of the risk of GC to the severity and extent of atrophic gastritis, intestinal metaplasia and dysplasia and no reversal of intestinal metaplasia and dysplasia in the presence of H. pylori eradication presume that gastroprotective agents should be used for primary and secondary prevention. Experimental and clinical findings can lead to the conclusion that rebamipide is a highly effective and safe agent for the primary and secondary prevention of GC in patients with and without H. pylori infection, by optimizing anti-Helicobacter therapy, its anti-inflammatory effect and ability to restore the cellular structure of the gastric epithelium.

Management of Helicobacter pylori infection-the Maastricht V/Florence Consensus Report

Important progress has been made in the management of Helicobacter pylori infection and in this fifth edition of the Maastricht Consensus Report, key aspects related to the clinical role of H. pylori were re-evaluated in 2015. In the Maastricht V/Florence Consensus Conference, 43 experts from 24 countries examined new data related to H. pylori in five subdivided workshops: (1) Indications/Associations, (2) Diagnosis, (3) Treatment, (4) Prevention/Public Health, (5) H. pylori and the Gastric Microbiota. The results of the individual workshops were presented to a final consensus voting that included all participants. Recommendations are provided on the basis of the best available evidence and relevance to the management of H. pylori infection in the various clinical scenarios.

Helicobacter pylori Clarithromycin Resistance and Treatment Failure Are Common in the USA

BACKGROUND

Helicobacter pylori antibiotic resistance leads to frequent treatment failure. However, the current US prevalence of H. pylori clarithromycin resistance and treatment failure is unknown.

AIMS

To determine the prevalence of clarithromycin-resistant H. pylori and its impact on treatment failure in the USA.

METHODS

A multicenter, retrospective, cohort study for clarithromycin-resistant H. pylori was conducted over four academic medical centers in different geographic regions of the USA. Gastric biopsy material, residual from standard clinical pathologic examination, was examined for clarithromycin resistance by DNA sequencing of H. pylori 23S rRNA.

RESULTS

One hundred and twenty-four cases of H. pylori gastritis were examined from medical centers in four different geographic regions of the USA. The overall prevalence of clarithromycin resistance was 32.3 % (range 23.1-45.8 %). There was no significant difference in the prevalence of clarithromycin resistance by study site, gender, age, or race/ethnicity. In a subset of 67 patients that had clinical follow-up data, the overall prevalence of clarithromycin resistance was 31.3 %. There was a 2.9-fold increase (p = 0.002) in treatment failure for cases with clarithromycin resistance (57.1 %) compared to wildtype H. pylori (19.6 %).

CONCLUSIONS

H. pylori clarithromycin resistance in the USA exceeds the estimated 20 % prevalence compatible with successful empiric antibiotic therapy. This resistance resulted in a significant rate of treatment failure in all sites surveyed. Empiric therapy in the USA should be used with caution until there is better regional or local determination of H. pylori antibiotic resistance.

Eradication of Helicobacter pylori Infection

Helicobacter pylori infects about 50 % of the world's population, causing at a minimum chronic gastritis. A subset of infected patients will ultimately develop gastric or duodenal ulcer disease, gastric adenocarcinoma, or MALT (mucosa-associated lymphoid tissue) lymphoma. Eradication of H. pylori requires complex regimens that include acid suppression and multiple antibiotics. The efficacy of treatment using what were once considered standard regimens have declined in recent years, mainly due to widespread development of antibiotic resistance. Addition of bismuth to standard triple therapy regimens, use of alternate antibiotics, or development of alternative regimens using known therapies in novel combinations have improved treatment efficacy in specific populations, but overall success of eradication remains less than ideal. Novel regimens under investigation either in vivo or in vitro, involving increased acid suppression ideally with fewer antibiotics or development of non-antibiotic treatment targets, show promise for future therapy.

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.

Sequential Therapy for Helicobacter pylori Infection in Treatment-naïve Children

The goal of first-line Helicobacter pylori therapy is to reach an eradication rate of 90% to avoid further investigations, antibiotic use, and spreading of resistant strains.

AIM

To evaluate the eradication rate of high-dose sequential therapy in treatment-naïve children and to assess factors associated with failure.

METHODS

Prospective data assessed in a registry from nine European centers between October 2009 and December 2011. Children with biopsy-proven Helicobacter pylori infection were prescribed 5 days of esomeprazole and amoxicillin, followed by 5 days of esomeprazole, clarithromycin, and metronidazole according to bodyweight. Eradication was assessed after 8-12 weeks. Primary endpoint was the eradication rate in children who received at least one dose and had follow-up data. Multivariate analysis evaluated potential factors for treatment success including sex, age, center, migrant status, antibiotic resistance, and adherence to therapy.

RESULTS

Follow-up was available in 209 of 232 patients (age range 3.1-17.9 years, 118 females). Primary resistance occurred for clarithromycin in 30 of 209 (14.4%), for metronidazole in 32 (15.3%), for both antibiotics in 7 (3.3%), and culture failed in 6 (2.9%). Eradication was achieved in 168 of 209 children (80.4%, 95% CI 75.02-85.78), in 85.8% with no resistance, 72.6% with single resistance, and 28.6% with double resistance. Independent factors affecting eradication rate included resistance to clarithromycin (adjusted ORs 0.27 (0.09-0.84), p = .024), to metronidazole (0.25 (0.009-0.72), p = .010) or to both (0.04 (0.01-0.35), p = .004), and intake of ≤ 90% of prescribed drugs (0.03 (0.01-0.18), p < .001).

CONCLUSION

A high-dose 10-day sequential therapy cannot be recommended in treatment-naïve children.

Review article: the global emergence of Helicobacter pylori antibiotic resistance

BACKGROUND

Helicobacter pylori is one of the most prevalent global pathogens and can lead to gastrointestinal disease including peptic ulcers, gastric marginal zone lymphoma and gastric carcinoma.

AIM

To review recent trends in H. pylori antibiotic resistance rates, and to discuss diagnostics and treatment paradigms.

METHODS

A PubMed literature search using the following keywords: Helicobacter pylori, antibiotic resistance, clarithromycin, levofloxacin, metronidazole, prevalence, susceptibility testing.

RESULTS

The prevalence of bacterial antibiotic resistance is regionally variable and appears to be markedly increasing with time in many countries. Concordantly, the antimicrobial eradication rate of H. pylori has been declining globally. In particular, clarithromycin resistance has been rapidly increasing in many countries over the past decade, with rates as high as approximately 30% in Japan and Italy, 50% in China and 40% in Turkey; whereas resistance rates are much lower in Sweden and Taiwan, at approximately 15%; there are limited data in the USA. Other antibiotics show similar trends, although less pronounced.

CONCLUSIONS

Since the choice of empiric therapies should be predicated on accurate information regarding antibiotic resistance rates, there is a critical need for determination of current rates at a local scale, and perhaps in individual patients. Such information would not only guide selection of appropriate empiric antibiotic therapy but also inform the development of better methods to identify H. pylori antibiotic resistance at diagnosis. Patient-specific tailoring of effective antibiotic treatment strategies may lead to reduced treatment failures and less antibiotic resistance.

Antibiotic treatment for Helicobacter pylori: Is the end coming?

Infection with the Gram-negative pathogen Helicobacter pylori (H. pylori) has been associated with gastro-duodenal disease and the importance of H. pylori eradication is underscored by its designation as a group I carcinogen. The standard triple therapy consists of a proton pump inhibitor, amoxicillin and clarithromycin, although many other regimens are used, including quadruple, sequential and concomitant therapy regimens supplemented with metronidazole, clarithromycin and levofloxacin. Despite these efforts, current therapeutic regimens lack efficacy in eradication due to antibiotic resistance, drug compliance and antibiotic degradation by the acidic stomach environment. Antibiotic resistance to clarithromycin and metronidazole is particularly problematic and several approaches have been proposed to overcome this issue, such as complementary probiotic therapy with Lactobacillus. Other studies have identified novel molecules with an anti-H. pylori effect, as well as tailored therapy and nanotechnology as viable alternative eradication strategies. This review discusses current antibiotic therapy for H. pylori infections, limitations of this type of therapy and predicts the availability of newly developed therapies for H. pylori eradication.

Kyoto global consensus report on Helicobacter pylori gastritis

OBJECTIVE

To present results of the Kyoto Global Consensus Meeting, which was convened to develop global consensus on (1) classification of chronic gastritis and duodenitis, (2) clinical distinction of dyspepsia caused by Helicobacter pylori from functional dyspepsia, (3) appropriate diagnostic assessment of gastritis and (4) when, whom and how to treat H. pylori gastritis.

DESIGN

Twenty-three clinical questions addressing the above-mentioned four domains were drafted for which expert panels were asked to formulate relevant statements. A Delphi method using an anonymous electronic system was adopted to develop the consensus, the level of which was predefined as ≥80%. Final modifications of clinical questions and consensus were achieved at the face-to-face meeting in Kyoto.

RESULTS

All 24 statements for 22 clinical questions after extensive modifications and omission of one clinical question were achieved with a consensus level of >80%. To better organise classification of gastritis and duodenitis based on aetiology, a new classification of gastritis and duodenitis is recommended for the 11th international classification. A new category of H. pylori-associated dyspepsia together with a diagnostic algorithm was proposed. The adoption of grading systems for gastric cancer risk stratification, and modern image-enhancing endoscopy for the diagnosis of gastritis, were recommended. Treatment to eradicate H. pylori infection before preneoplastic changes develop, if feasible, was recommended to minimise the risk of more serious complications of the infection.

CONCLUSIONS

A global consensus for gastritis was developed for the first time, which will be the basis for an international classification system and for further research on the subject.

Helicobacter pylori second-line rescue therapy with levofloxacin- and bismuth-containing quadruple therapy, after failure of standard triple or non-bismuth quadruple treatments

BACKGROUND

The most commonly used second-line Helicobacter pylori eradication regimens are bismuth-containing quadruple therapy and levofloxacin-containing triple therapy, both offering suboptimal results. Combining bismuth and levofloxacin may enhance the efficacy of rescue eradication regimens.

AIMS

To evaluate the efficacy and tolerability of a second-line quadruple regimen containing levofloxacin and bismuth in patients whose previous H. pylori eradication treatment failed.

METHODS

This was a prospective multicenter study including patients in whom a standard triple therapy (PPI-clarithromycin-amoxicillin) or a non-bismuth quadruple therapy (PPI-clarithromycin-amoxicillin-metronidazole, either sequential or concomitant) had failed. Esomeprazole (40 mg b.d.), amoxicillin (1 g b.d.), levofloxacin (500 mg o.d.) and bismuth (240 mg b.d.) was prescribed for 14 days. Eradication was confirmed by (13) C-urea breath test. Compliance was determined through questioning and recovery of empty medication envelopes. Incidence of adverse effects was evaluated by questionnaires.

RESULTS

200 patients were included consecutively (mean age 47 years, 67% women, 13% ulcer). Previous failed therapy included: standard clarithromycin triple therapy (131 patients), sequential (32) and concomitant (37). A total of 96% took all medications correctly. Per-protocol and intention-to-treat eradication rates were 91.1% (95%CI = 87-95%) and 90% (95%CI = 86-94%). Cure rates were similar regardless of previous (failed) treatment or country of origin. Adverse effects were reported in 46% of patients, most commonly nausea (17%) and diarrhoea (16%); 3% were intense but none was serious.

CONCLUSIONS

Fourteen-day bismuth- and levofloxacin-containing quadruple therapy is an effective (≥90% cure rate), simple and safe second-line strategy in patients whose previous standard triple or non-bismuth quadruple (sequential or concomitant) therapies have failed.

Pyridodiazepine amines are selective therapeutic agents for helicobacter pylori by suppressing growth through inhibition of glutamate racemase but are predicted to require continuous elevated levels in plasma to achieve clinical efficacy

A pyridodiazepine amine inhibitor of Helicobacter pylori glutamate racemase (MurI) was characterized. The compound was selectively active against H. pylori, and growth suppression was shown to be mediated through the inhibition of MurI by several methods. In killing kinetics experiments, the compound showed concentration-independent activity, with about a 2-log loss of viability in 24 h. A demonstration of efficacy in a mouse infection model was attempted but not achieved, and this was attributed to the failure to attain extended exposure levels above the MIC for >95% of the time. This index and magnitude were derived from pharmacokinetic-pharmacodynamic (PK-PD) studies with amoxicillin, another inhibitor of peptidoglycan biosynthesis that showed slow killing kinetics similar to those of the pyridodiazepine amines. These studies indicate that MurI and other enzymes involved in peptidoglycan biosynthesis may be less desirable targets for monotherapy directed against H. pylori if once-a-day dosing is required.

GenoType HelicoDR test in the determination of antimicrobial resistance of Helicobacter pylori in Korea

OBJECTIVE

Antimicrobial resistance of Helicobacter pylori is most important factor in eradication success. GenoType HelicoDR test has been developed for rapid detection of antimicrobial resistance. The present study evaluated the clinical usefulness of GenoType HelicoDR test in Korea.

MATERIALS AND METHODS

To detect 23S rRNA for clarithromycin resistance and gyrA mutations for fluoroquinolone resistance, both DNA sequencing after minimal inhibitory test (MIC) and GenoType HelicoDR test were performed in H. pylori isolates from the gastric mucosa of 101 patients. The eradication results of clarithromycin and moxifloxacin-containing triple therapy were evaluated by the 23S rRNA and gyrA mutations.

RESULTS

For 42 isolates with A2143G mutation by GenoType HelicoDR, 83.3% (35/42) of concordance rate was estimated with DNA sequencing method and 85.7% (36/42) for MIC test. For 43 isolates with N87K mutation by GenoType HelicoDR, 71.1% (31/43) of concordance rate was estimated with DNA sequencing and 88.4% (38/43) for MIC test. The sensitivity and specificity of GenoType HelicoDR test in determination of 23S rRNA mutation were 94.9% and 87.1%, and those of gyrA 98.2% and 80.0%. The sensitivity and specificity of GenoType HelicoDR test in determination of clarithromycin resistance based on MIC test were 55.0% and 80.0%, for fluoroquinolone 74.4% and 70.0%.

CONCLUSION

GenoType HelicoDR test is useful to determine mutations responsible for clarithromycin or fluoroquinolone-containing eradication failure but has a limitation for the clinical applicability in determination of resistance.

Therapy of Helicobacter pylori: present medley and future prospective

The increasing prevalence of antimicrobial resistance has warned clinicians to adopt new strategies for dealing with the H. pylori infection. The success of various therapeutic regimens has recently declined to unacceptable levels. To date, first line therapies (including concomitant therapy and hybrid therapy), second line therapies (including bismuth-containing quadruple therapy and levofloxacin-containing therapy), and third line therapy (culture-guided therapy) had been introduced. In the near future, treatment of H. pylori is entering into a completely new resistance era. In this setting, despite the recent progress, we may only be targeting the patients with problematic H. pylori. Local preference for antibiotic selection should be an inevitable article in each therapeutic regimen worldwide. Meanwhile, improving the patients' compliance protocols and observed side effects in suggested therapeutic regimens should be considered cautiously. The new strategies in treatment should be adopted based upon local resistance patterns, which requires physician's resistance about the recommended guidelines. Designing new therapeutic regimen, which contains most effective available antibiotics with less possible side effects and high patient compliance, represents a challenging task in treatment of H. pylori infections.

Rational Helicobacter pylori therapy: evidence-based medicine rather than medicine-based evidence

Data are available such that choice of Helicobacter pylori therapy for an individual patient can be reliably predicted. Here, treatment success is defined as a cure rate of 90% or greater. Treatment outcome in a population or a patient can be calculated based on the effectiveness of a regimen for infections with susceptible and with resistant strains coupled with the knowledge of the prevalence of resistance (ie, based on formal measurement, clinical experience, or both). We provide the formula for predicting outcome and we illustrate the calculations. Because clarithromycin-containing triple therapy and 10-day sequential therapy are now only effective in special populations, they are considered obsolete; neither should continue to be used as empiric therapies (ie, 7- and 14-day triple therapies fail when clarithromycin resistance exceeds 5% and 15%, respectively, and 10-day sequential therapy fails when metronidazole resistance exceeds 20%). Therapy should be individualized based on prior history and whether the patient is in a high-risk group for resistance. The preferred choices for Western countries are 14-day concomitant therapy, 14-day bismuth quadruple therapy, and 14-day hybrid sequential-concomitant therapy. We also provide details regarding the successful use of fluoroquinolone-, rifabutin-, and furazolidone-containing therapies. Finally, we provide recommendations for the efficient development (ie, identification and optimization) of new regimens, as well as how to prevent or minimize failures. The trial-and-error approach for identifying and testing regimens frequently resulted in poor treatment success. The described approach allows outcome to be predicted and should simplify treatment and drug development.

Helicobacter pylori: Future perspectives in therapy reflecting three decades of experience

The rising prevalence of antibiotic resistance has created a need to reassess the established Helicobacter pylori (H. pylori) eradication protocols, and to develop new ones. Various bacterial and host factors are evaluated, and their contribution to eradication failure is estimated. For a long time being considered the cornerstone eradication scheme, the standard triple therapy has been replaced with novel, more efficient regimens, namely sequential and concomitant, along with the emergence of a new design of bismuth quadruple therapy. A rescue levofloxacin based regimen has overcome the fear of therapy failure due to higher prevalence of dual resistant (clarithromycin and metronidazole) H. pylori. Culture-free and efficient susceptibility test are reestablishing the concept of tailored therapy, making eradication success close to originally desirable rates. Alleviating therapy side effects and improving patient compliance are as important as choosing appropriate eradication schemes, so various probiotic compound supplements are taken into consideration. Finally, we summarize the emerging efforts and obstacles in creating efficient H. pylori vaccine.

Eradication of Helicobacter pylori infection: Which regimen first?

Helicobacter pylori (H. pylori) is a well-known human pathogen that plays an essential role in the pathogenesis of chronic gastritis, peptic ulcer disease, and gastric malignancies. Although H. pylori is susceptible to several antimicrobials, this infection has proven challenging to cure because of the increasing prevalence of bacterial strains that are resistant to the most commonly used antimicrobials, particularly clarithromycin. An effective (i.e., > 90%) first-line therapy is mandatory for avoiding supplementary treatments and testing, and more importantly for preventing the development of secondary resistance. This study reviews the recent literature on first-line therapies for H. pylori. The eradication rates following standard triple therapy (a proton pump inhibitor plus amoxicillin and clarithromycin) for H. pylori infection are declining worldwide. Several first-line strategies have been proposed to increase the eradication rate, including extending the treatment duration to 14 d, the use of a four-drug regimen (bismuth-containing quadruple, sequential, and concomitant treatments), and the use of novel antibiotics, such as fluoroquinolones. However, the efficacy of these regimens is controversial. A first-line eradication regimen should be based on what works best in a defined geographical area and must take into account the prevalence of antimicrobial resistance in that region.

Effect of fluoroquinolone resistance on 14-day levofloxacin triple and triple plus bismuth quadruple therapy

OBJECTIVE

Levofloxacin has been proposed to replace clarithromycin for Helicobacter pylori treatment. Seven- and 10-day fluoroquinolone triple therapies have generally failed to achieve cure rates of ≥90%, whereas 14-day therapy has achieved 95% success. The aim was to assess the efficacy and effect of fluoroquinolone resistance on 14-day levofloxacin-containing triple therapy with or without the addition of bismuth.

DESIGN

Helicobacter pylori-positive patients with functional dyspepsia or healed peptic ulcers were randomized to receive lansoprazole 30 mg b.i.d., amoxicillin 1000 mg b.i.d., and levofloxacin 500 mg daily with (B-LAL) or without (LAL) bismuth potassium citrate 220 mg b.i.d. for 14 days. Eradication was assessed by ¹³C-urea breath testing 4 weeks after completing treatment. Antimicrobial susceptibility was by the agar dilution method. Success was defined as PP success ≥90%.

RESULTS

A total of 152 of 161 patients (81 LAL and 80 B-LAL) enrolled completed treatment. The PP rates were 94.6% (70/74; 95% CI, 86.9-97.9%) with B-LAL and 85.9% (95% CI, 76.5-91.9%) with LAL (p = .07); the ITT eradication rates were 87.5% (95% CI, 78.5-93.1%) with B-LAL and 82.7% (95% CI, 73-89.4%) with LAL (p = .39). Levofloxacin resistance was present in 30.3%. Treatment success was excellent with susceptible strains (97.5%) versus resistant strains (70.6%) for B-LAL and 97.3% versus 37.5% for LAL, respectively.

CONCLUSIONS

Fourteen-day fluoroquinolone therapy was highly effective when fluoroquinolone resistance rates are <12%. The addition of bismuth maintained effectiveness with fluoroquinolone resistance as high as 25%.

Real-Time PCR detection and quantitation of Helicobacter pylori clarithromycin-resistant strains in archival material and correlation with Sydney classification

BACKGROUND

Helicobacter pylori (H. pylori), infects gastric mucosa causing gastritis. Treatment failure is mainly due to certain genetic changes in the peptidyltransferase loop of 23S rRNA of the microorganism. The aim of the study was to evaluate genetic changes in gastric biopsies of H. pylori (+) patients that lead to clarithromycin resistance and to correlate them with histology data.

METHODS

A total of 150 H. pylori (+) gastric biopsies were studied, taken before and after eradication therapy from 75 dyspeptic patients divided in 2 groups: group A consisted of 25 H. pylori (+) triple-therapy resistant patients and group B consisted of 50 H. pylori (+) successfully treated patients. Histological classification of the H. pylori (+) gastritis was done according to the Sydney criteria. Genetic material was analyzed with the ClariRes™ RT-PCR bi-probe based assay for the determination of point mutations in the 23S rRNA gene and with a Quantitative-RT-PCR (Q-RT-PCR) method for the quantitation of H. pylori.

RESULTS

We showed that in 18/ 25 group A patients certain point mutations of 23S rRNA at sites A2142C, A2142G and A2143G had occurred. Nine of these 18 mutated cases (50%) were characterized as mixed infections. Mixed infections in 2/50 patients of group B were also observed. Using Q-RT-PCR, we found that gastric mucosal density of H. pylori correlates well with bacterial colonization. There was a statistically significant association (P<0.005) between the presence of the detected H. pylori genetic alterations and inflammation, activity and H. pylori density as histologically determined.

CONCLUSION

Certain point mutations in H. pylori genome that affect susceptibility to clarithromycin correlate with histological features of gastritis.