Polymorphism of interleukin-1beta affects the eradication rates of Helicobacter pylori by triple therapy

Efficacy of Helicobacter pylori Eradication Based on Rabeprazole–Bismuth–Tetracycline–Tinidazole Regimen in Vietnamese Patients with Duodenal Ulcers

(1) Background: In Vietnam, H. pylori bacteria has a resistance rate of 63% to the antibiotic clarithromycin. The initial therapy of H. pylori eradication with a standard three-drug regimen has low efficacy. Objective: Assess the efficacy of H. pylori eradication therapy which uses a four-drug regimen of rabeprazole–bismuth–tetracycline–tinidazole in patients with duodenal ulcers. (2) Methods: We performed gastrointestinal endoscopy on patients with a diagnosis of duodenal ulcers, gastric mucosa biopsy for a rapid urease test, and histopathology to diagnose H. pylori bacteria before and after treatment. Treatment for eradication of H. pylori bacteria using a rabeprazole–bismuth–tetracycline–tinidazole regimen was prescribed for 14 days. (3) Results: The rate of successful H. pylori eradication treatment according to per protocol (PP) and intention to treat (ITT) was 91.3% (95%CI: 84.8–96.7) and 82.4% (95%CI: 74.5–89.2) respectively. The success rate of H. pylori eradication therapy in males was 96.0% (95%CI: 92–100), higher than in females, which was 70.6% (95%CI: 47.1–88.2), p < 0.01. (4) Conclusions: Treatment of H. pylori with rabeprazole–bismuth–tetracycline–tinidazole regimen is highly effective. Men had higher H. pylori eradication results than women.

Effects of CYP2C19 genetic polymorphisms on the cure rates of H. pylori in patients treated with the proton pump inhibitors: An updated meta-analysis

Background: The cure rates of Helicobacter pylori (H. pylori) treatment using a proton pump inhibitor (PPI) are gradually decreasing due to antibiotic resistance, poor compliance, high gastric acidity, and cytochrome P450 2C19 (CYP2C19) polymorphism, and the effects of PPI depend on metabolic enzymes, cytochrome P450 enzymes. The aim of this meta-analysis was to determine whether CYP2C19 polymorphisms affect H. pylori cure rates in patients treated with different proton pump inhibitors (PPIs) according to stratified analysis.

Materials and methods: The literature was searched with the key words “H. pylori” and “CYP2C19” in PubMed, CNKI, and Wanfang up to 31 May 2022, and the studies were limited to clinical observational or randomized controlled trials (RCTs). Finally, seven RCTs and 29 clinical observational studies met the inclusion criteria and were used for the meta-analysis via STATA version 16.

Results: The cure rates were significantly different between genotypes of homozygous extensive metabolizers (EM) and poor metabolizers (PM) (OR = 0.58, 95% CI: 0.47–0.71) and between EM and heterozygous extensive metabolizers (IM) (OR = 0.71, 95% CI: 0.59–0.86), but not between IM and PM. Moreover, there was a significantly lower H. pylori cure rate in EM subjects than that in IM subjects when treated with omeprazole (66.4% vs. 84.1%), lansoprazole (76.1% vs. 85.6%), but not rabeprazole, esomeprazole, or pantoprazole. In addition, there was a significantly lower H. pylori cure rate in EM subjects than that in IM subjects when treated with a PPIs for 7 days (77.4% vs. 82.1%), but not 14 days (85.4% vs. 90.0%).

Conclusion: Carriers of CYP2C19 loss-of-function variant alleles (IM and PM) exhibit a significantly greater cure rate of H. pylori than noncarriers (EM) regardless of other factors (84.7% vs. 79.2%). In addition, pantoprazole- and rabeprazole-based quadruple therapy for H. pylori treatment is less dependent on the CYP2C19 genotype and should be prioritized in Asian populations with H. pylori.

Helicobacter pylori infection: from standard to alternative treatment strategies

Helicobacter pylori is the major component of the gastric microbiome of infected individuals and one of the aetiological factors of chronic gastritis, peptic ulcer disease and gastric cancer. The increasing resistance to antibiotics worldwide has made the treatment of H. pylori infection a challenge. As a way to overhaul the efficacy of currently used H. pylori antibiotic-based eradication therapies, alternative treatment strategies are being devised. These include probiotics and prebiotics as adjuvants in H. pylori treatment, antimicrobial peptides as alternatives to antibiotics, photodynamic therapy ingestible devices, microparticles and nanoparticles applied as drug delivery systems, vaccines, natural products, and phage therapy. This review provides an updated synopsis of these emerging H. pylori control strategies and discusses the advantages, hurdles, and challenges associated with their development and implementation. An effective human vaccine would be a major achievement although, until now, projects regarding vaccine development have failed or were discontinued. Numerous natural products have demonstrated anti-H. pylori activity, mostly in vitro, but further clinical studies are needed to fully disclose their role in H. pylori eradication. Finally, phage therapy has the potential to emerge as a valid alternative, but major challenges remain, namely the isolation of more H. pylori strictly virulent bacterio(phages).

The effect of CYP2C19 gene polymorphism on the eradication rate of Helicobacter pylori by proton pump inhibitors-containing regimens in Asian populations: a meta-analysis

Premise: The effects of proton pump inhibitors (PPI) depend on metabolic enzyme CYP2C19 that has different activity due to gene polymorphism. The purpose of this meta-analysis is to determine the potential effects of CYP2C19 polymorphism on the efficiency of PPI-based treatment. Materials & methods: The PubMed, EMBASE, Cochrane Library, etc. were searched for relevant articles published in English or Chinese from inception to 31 May 2020. Finally, 26 randomized controlled trials and 15 cohort studies met the inclusion criteria and used for the meta-analysis via STATA version 15. Results: Poor metabolizer (PM) genotype Helicobacter pylori eradication rates were highest for Asian individuals receiving triple or quadruple first-line therapy based on PPIs (p < 0.05). CYP2C19 polymorphism could influence H. pylori eradication rate only in Mainland China and Japan (p < 0.05). Conclusion: PM genotype facilitates the elimination of H. pylori in Asian populations. Rabeprazole-, esomeprazole- and pantoprazole-based eradication program was less affected by the CYP2C19 polymorphism.

The Influence of IL-1B Gene Polymorphisms on H. pylori Infection and Triple Treatment Response Among Jordanian Population

Background

Helicobacter pylori (H. pylori) is considered the main cause of gastritis, peptic ulcer and gastric carcinoma in the human populations. H. pylori infection influences the secretion level of several proinflammatory cytokines including IL-1β, which encoded by the IL-1B gene.

Objective

The current study aimed to investigate whether IL-1B gene polymorphisms are associated with H. pylori infection among the Jordanian population and responses to triple therapy.

Subjects and Methods

The gastroscopic examination was performed on 412 subjects for H. pylori infection diagnosis, 257 subjects were found to be infected by H. Pylori (positive cases), whereas 155 subjects were uninfected (negative controls). The IL-1B gene T-31C and C3954T polymorphisms were genotyped by PCR-RFLP.

Results

It was found that the T-31C polymorphism has a significant association with H. pylori infection (P<0.05), and the TT genotype frequency was significantly higher in infected subjects (50.2%) compared to controls (38.7%). On the other hand, no significant association was detected between C3954T SNPs and H. pylori infection among the Jordanian population. In addition, none of the examined polymorphisms were found to influence the responses to triple therapy.

Conclusion

The IL-1B gene T-31C SNP might be associated with an enhanced risk of H. pylori infection among the Jordanian population.

Retrospective study on outcome of salvage Helicobacter pylori eradication therapies based on molecular genetic susceptibility testing

BACKGROUND

Antimicrobial susceptibility of Helicobacter (H.) pylori is usually determined by phenotypic methods. When H. pylori cannot be grown owing to contaminations or delay in transport of gastric tissue samples to the microbiological laboratory, molecular genetic testing is a reasonable alternative. The aim of this retrospective study was to assess the outcome of salvage eradication treatments based on molecular genetic susceptibility testing.

METHODS

Data on 144 H. pylori PCR-positive gastric tissue samples of patients primarily with prior unsuccessful eradication treatments were retrospectively analyzed. Eradication treatments were recommended based on genotypic clarithromycin and/or levofloxacin susceptibility as tested by real-time PCR or reverse hybridization. Treatment success was assessed by attending physicians using urea breath test; stool-antigen ELISA; and microbiology/histopathology.

RESULTS

Overall success rate of molecular genetic testing-guided salvage treatments was low (68%); none of the regimens chosen was significantly better than another. Multivariable logistic regression analysis did not reveal any factors that may predict treatment failure.

CONCLUSIONS

Eradication success was poor despite susceptibility testing. Gastroenterologists are advised to prescribe recommended salvage treatments, considering recommended dosages and prolonged treatment duration.

Helicobacter pylori eradication: influence of interleukin-1beta -31 C/T polymorphism

Aim

To analyze the influence of the –31 C/T polymorphism of the interleukin-1β gene on Helicobacter pylori eradication therapy success in patients with functional dyspepsia.

Methods

Functional dyspepsia was diagnosed according to the Rome III criteria. All patients underwent upper gastrointestinal endoscopy, and gastric biopsies were obtained at screening and 12 months after randomization (last follow-up visit). Urease test and histological examination were performed to define the H. pylori status. Patients received twice-daily amoxicillin, clarithromycin and omeprazole for 10 days. Genotyping of the interleukin-1beta –31 C/T polymorphism (rs1143627) was performed using polymerase chain reaction-restriction fragment length polymorphism.

Results

One hundred forty-nine patients received treatment with triple therapy for H. pylori eradication. Only one patient was lost to follow-up, and adherence to study medication was 94.6%. A total of 148 patients (mean age 46.08 ± 12.24 years; 81.8% women) were evaluated for the influence of the interleukin-1beta –31 C/T polymorphism on the outcome of H. pylori eradication therapy. After treatment, bacteria were eradicated in 87% of patients (129/148). Genotype frequencies of the polymorphism were as follows: CC, 38/148 (25.7%); CT, 71/148 (47.9%); and TT, 39/148 (26.4%). Successful eradication rate was 78.9%, 94.4% and 82.1% for the CC, CT and TT genotypes, respectively. The CT genotype was significantly associated with successful H. pylori eradication (p = 0.039).

Conclusion

This study suggests that the CT genotype of the interleukin-1beta –31 C/T polymorphism plays a role in the successful eradication of H. pylori among patients with functional dyspepsia.

Pharmacogenomic testing: the case for CYP2C19 proton pump inhibitor gene-drug pairs

The use of proton pump inhibitors (PPIs) in the treatment of gastroesophageal reflux and related diseases is increasing, especially in the pediatric population. Prolonged use of PPIs has been associated with several adverse effects, including potentially life-threatening gastric and respiratory infections, which are related to dose or to the degree of gastric acid suppression. Genetic variation in the CYP2C19 gene gives rise to poor and extensive metabolizer phenotypes, which influence PPI clearance, efficacy and exposure. A recent paper linked lansoprazole-associated respiratory infections in children with the poor metabolizer phenotype. The case is made for implementing pharmacogenomic testing for the CYP2C19-PPI gene-drug pair and to dose accordingly in order to minimize PPI-associated infections.

Outcome of second- and third-line Helicobacter pylori eradication therapies based on antimicrobial susceptibility testing

OBJECTIVES

The objective of this study was to assess the outcome of antimicrobial susceptibility-guided therapies in Helicobacter pylori-infected individuals who had undergone unsuccessful prior eradication treatments.

METHODS

From October 2004 to December 2013, 481 H. pylori-positive patients with prior unsuccessful eradication treatments were administered susceptibility-guided salvage eradication treatments. Six months on, treatment outcome was assessed by urea breath test, stool antigen ELISA, Helicobacter urease test or microbiology and/or histopathology.

RESULTS

Resistance to metronidazole and clarithromycin was high in patients with prior unsuccessful eradication treatments and was dependent on the number of treatment failures. Susceptibility-guided salvage eradication treatments achieved eradication rates of nearly 70% in these patients. No particular regimen was significantly better than another.

CONCLUSIONS

Antimicrobial susceptibility testing prevents prescription of inefficient antimicrobials and enables individualized and promising salvage treatments in patients with prior unsuccessful eradication treatments.

Treatment of Helicobacter pylori infection: current status and future concepts

Helicobacter pylori (H. pylori) infection is highly associated with the occurrence of gastrointestinal diseases, including gastric inflammation, peptic ulcer, gastric cancer, and gastric mucosa-associated lymphoid-tissue lymphoma. Although alternative therapies, including phytomedicines and probiotics, have been used to improve eradication, current treatment still relies on a combination of antimicrobial agents, such as amoxicillin, clarithromycin, metronidazole, and levofloxacin, and antisecretory agents, such as proton pump inhibitors (PPIs). A standard triple therapy consisting of a PPI and two antibiotics (clarithromycin and amoxicillin/metronidazole) is widely used as the first-line regimen for treatment of infection, but the increased resistance of H. pylori to clarithromycin and metronidazole has significantly reduced the eradication rate using this therapy and bismuth-containing therapy or 10-d sequential therapy has therefore been proposed to replace standard triple therapy. Alternatively, levofloxacin-based triple therapy can be used as rescue therapy for H. pylori infection after failure of first-line therapy. The increase in resistance to antibiotics, including levofloxacin, may limit the applicability of such regimens. However, since resistance of H. pylori to amoxicillin is generally low, an optimized high dose dual therapy consisting of a PPI and amoxicillin can be an effective first-line or rescue therapy. In addition, the concomitant use of alternative medicine has the potential to provide additive or synergistic effects against H. pylori infection, though its efficacy needs to be verified in clinical studies.

Antiplatelet drug interactions with proton pump inhibitors

INTRODUCTION

Non-aspirin antiplatelet agents (e.g., clopidogrel, prasugrel, ticagrelor) are commonly prescribed for the prevention of recurrent cardiovascular events among patients with acute coronary syndromes (ACS) and/or those undergoing percutaneous coronary intervention (PCI). In addition, combination therapy with proton pump inhibitors (PPIs) is often recommended to attenuate gastrointestinal bleeding risk, particularly during dual antiplatelet therapy (DAPT) with clopidogrel and aspirin. Importantly, a pharmacological interaction between clopidogrel and some PPIs has been proposed based on mutual CYP450-dependent metabolism, but available evidence is inconsistent.

AREAS COVERED

This article provides an overview of the currently approved antiplatelet agents and PPIs, including their metabolic pathways. Additionally, the CYP450 isoenzyme at the center of the drug interaction, CYP2C19, is described in detail, and the available evidence on both the potential pharmacological interaction and influence on clinical outcomes are summarized and evaluated.

EXPERT OPINION

Although concomitant DAPT and PPI use reduces clopidogrel active metabolite levels and ex vivo-measured platelet inhibition, the influence of the drug interaction on clinical outcomes has been conflicting and largely reported from non-randomized observational studies. Despite this inconsistency, a clinically important interaction cannot be definitively excluded, particularly among patient subgroups with higher overall cardiovascular risk and potentially among CYP2C19 loss-of-function allele carriers.

[Low penetrance gene polymorphisms involved in Helicobacter pylori-immune response. Relevance on gastric cancer risk]

Gastric cancer is a complex pathology which represents a worldwide health burden due to its high prevalence and poor prognosis. Therefore, prevention and early detection are considered the best options for controlling the disease. Current research is based on the study of genetic variants that confer a higher risk and their interactions with environmental exposure. A deeper knowledge of factors involved on gastric cancer development may allow identification of those individuals at elevated risk and will provide useful predictive information for subgroups of patients who need surveillance or early treatment strategies. In the present paper we review in a comprehensive manner, the most recent published studies on the contribution of gene polymorphisms and Helicobacter pylori infection to gastric cancer risk.

The Human Gastric Pathogen Helicobacter pylori and Its Association with Gastric Cancer and Ulcer Disease

With the momentous discovery in the 1980's that a bacterium, Helicobacter pylori, can cause peptic ulcer disease and gastric cancer, antibiotic therapies and prophylactic measures have been successful, only in part, in reducing the global burden of these diseases. To date, ~700,000 deaths worldwide are still attributable annually to gastric cancer alone. Here, we review H. pylori's contribution to the epidemiology and histopathology of both gastric cancer and peptic ulcer disease. Furthermore, we examine the host-pathogen relationship and H. pylori biology in context of these diseases, focusing on strain differences, virulence factors (CagA and VacA), immune activation and the challenges posed by resistance to existing therapies. We consider also the important role of host-genetic variants, for example, in inflammatory response genes, in determining infection outcome and the role of H. pylori in other pathologies—some accepted, for example, MALT lymphoma, and others more controversial, for example, idiopathic thrombocytic purpura. More recently, intriguing suggestions that H. pylori has protective effects in GERD and autoimmune diseases, such as asthma, have gained momentum. Therefore, we consider the basis for these suggestions and discuss the potential impact for future therapeutic rationales.

Eradication of H. pylori Infection: the Challenge is on if Standard Therapy Fails

The recommended standard triple therapy for Helicobacter pylori infection, consisting of a proton pump inhibitor, clarithromycin and amoxicillin or metronidazole, can reach eradication rates in over 90%. However, in recent years resistance to antibiotics has increased and eradication rates have declined. Approximately one in five patients need a second-line therapy because eradication therapy fails. Second-line treatment with a bismuth-based quadruple therapy leads to satisfactory eradication rates, but bismuth is not available in many countries. Modern second- and third-line treatments can only be successful if they are adapted to the current resistance situation and they need to evolve continuously. Moreover, pharmacodynamic effects due to polymorphisms of the cytochrome P450 system are important. Because therapy adherence is significantly associated with therapy success, modern regimens if possible should be easy to take and well tolerated. In recent years, various novel salvage-therapy regimens have been investigated that significantly improve treatment options.

Effects of CYP2C19, MDR1, and interleukin 1-B gene variants on the eradication rate of Helicobacter pylori infection by triple therapy with pantoprazole, amoxicillin, and metronidazole

OBJECTIVE

Eradication of H. pylori is an important treatment strategy in peptic ulcer patients. Current regimens of eradication consist of proton pump inhibitor (PPI) and two antibiotics. Effects of PPI may depend on their metabolism, and other factors important for the pathophysiology of peptic ulcer disease. Aim of the present study was to evaluate an association of CYP2C19, MDR1, and IL-1B polymorphisms with the eradication rate of H. pylori in Polish Caucasian patients treated with a triple therapy of pantoprazole, amoxicillin, and metronidazole.

METHODS

A total of 139 peptic ulcer patients, positive for H. pylori infection, were treated with triple therapy (pantoprazole + amoxicillin + metronidazole). Subsequently, the patients were divided into two groups (group 1, success, and group 2, failure of eradication after therapy) and genotyped by the PCR-RFLP method for the presence of CYP2C19 variant alleles (*2, *3, and *17), and MDR1 3435C>T and IL-1B +3954C>T polymorphisms. Pantoprazole serum concentrations were measured using the HPLC method.

RESULTS

No significant differences in frequency or distribution of CYP2C19 genotypes were found between the two groups of patients (i.e., with successful H. pylori eradication and treatment failure). However, any carrier of defective CYP2C19*2/*2 genotype was found among patients with treatment failure. Similarly, MDR1 and IL-1B genotypes were found to be significantly associated with the success or failure of H. pylori eradication. Univariate and multivariate analysis of the genotypes did not reveal any significant association between the genotypes and H. pylori eradication. Pantoprazole concentrations differed significantly, and were the highest in patients with defective allele CYP2C19*2 carriers and lowest in hyperactive genotype homozygotes CYP2C19*17/*17.

CONCLUSION

The results suggest that the CYP2C19 genotype contrary to MDR1 and IL-1B genotypes may have an impact on the efficacy of H. pylori eradication in peptic ulcer patients treated with pantoprazole in Polish Caucasian peptic ulcer patients administered pantoprazole, amoxicillin, and metronidazole.

Effects of CYP2C19, MDR1, and interleukin 1-B gene variants on the eradication rate of Helicobacter pylori infection by triple therapy with pantoprazole, amoxicillin, and metronidazole

OBJECTIVE

Eradication of H. pylori is an important treatment strategy in peptic ulcer patients. Current regimens of eradication consist of proton pump inhibitor (PPI) and two antibiotics. Effects of PPI may depend on their metabolism, and other factors important for the pathophysiology of peptic ulcer disease. Aim of the present study was to evaluate an association of CYP2C19, MDR1, and IL-1B polymorphisms with the eradication rate of H. pylori in Polish Caucasian patients treated with a triple therapy of pantoprazole, amoxicillin, and metronidazole.

METHODS

A total of 139 peptic ulcer patients, positive for H. pylori infection, were treated with triple therapy (pantoprazole + amoxicillin + metronidazole). Subsequently, the patients were divided into two groups (group 1, success, and group 2, failure of eradication after therapy) and genotyped by the PCR-RFLP method for the presence of CYP2C19 variant alleles (*2, *3, and *17), and MDR1 3435C>T and IL-1B +3954C>T polymorphisms. Pantoprazole serum concentrations were measured using the HPLC method.

RESULTS

No significant differences in frequency or distribution of CYP2C19 genotypes were found between the two groups of patients (i.e., with successful H. pylori eradication and treatment failure). However, any carrier of defective CYP2C19*2/*2 genotype was found among patients with treatment failure. Similarly, MDR1 and IL-1B genotypes were found to be significantly associated with the success or failure of H. pylori eradication. Univariate and multivariate analysis of the genotypes did not reveal any significant association between the genotypes and H. pylori eradication. Pantoprazole concentrations differed significantly, and were the highest in patients with defective allele CYP2C19*2 carriers and lowest in hyperactive genotype homozygotes CYP2C19*17/*17.

CONCLUSION

The results suggest that the CYP2C19 genotype contrary to MDR1 and IL-1B genotypes may have an impact on the efficacy of H. pylori eradication in peptic ulcer patients treated with pantoprazole in Polish Caucasian peptic ulcer patients administered pantoprazole, amoxicillin, and metronidazole.

Influence of inflammatory cytokine polymorphisms on eradication rates of Helicobacter pylori

Pro-inflammatory cytokines and anti-inflammatory cytokines are produced in gastric mucosa from inflammatory cells activated by Helicobacter pylori (H. pylori) infection. Of the inflammatory cytokines, interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha have a potent inhibitive effect on gastric acid production. Polymorphisms in these genes are associated with individual differences in cytokine messenger RNA levels, which result in different gastric mucosal inflammation, different acid inhibition and different gastroduodenal disease risks in response to H. pylori infection. The sustained higher intragastric pH during an eradication therapy is known to be one of the therapeutic determinants of the H. pylori eradication as well as antibiotics resistance and poor compliance. The IL-1B-511 polymorphism is related to eradication rate, and, in combined analysis of previous reports, the eradication rate in patients with the IL-1B-511 C/C genotype (77.4%, 209/270), low IL-1beta producer genotype, is lower than that of the IL-1B-511 C/T and T/T genotypes (87.2%, 631/724) (Odds ratio for eradication failure: 1.98, 95% confidence interval: 1.38-2.84, P = 0.0002). Moreover, the odds ratio of combined CYP2C19 rapid metabolizer-IL-1B-511 C/C type for eradication failure is 11.15 (5.23-23.78) times that of the CYP2C19 poor metabolizer-IL-1B-511 non-C/C type. However, there is no positive data indicating the role of other inflammatory cytokine polymorphisms (e.g. IL-1RN, TNF-A or IL-10) in eradication therapy. Nevertheless, the studies show that inflammatory cytokine polymorphisms, especially the IL-1B-511 T/T genotype, are the determinants of eradication by affecting gastric acid secretion and mucosal inflammation. Therefore, the tailored eradication therapy, considering inflammatory cytokine polymorphisms, may be effective for the higher eradication rates.

Annual change of primary resistance to clarithromycin among Helicobacter pylori isolates from 1996 through 2008 in Japan

BACKGROUND

Recent studies have shown that the combination of proton pump inhibitor, amoxicillin and clarithromycin is one of the best choices for Helicobacter pylori eradication therapy. However, increasing number of cases of H. pylori infection showing resistance to clarithromycin therapy has been reported and this is currently the main cause of eradication failure. We investigated the annual changes of the antimicrobial susceptibility to clarithromycin, amoxicillin and minocycline during a period of 12 years in Japan.

METHODS

This study comprised 3521 patients (mean age (SD), 55.4 (13.7) years-old, 2467 males and 1054 females) positive for H. pylori as assessed by microaerobic bacterial culture from 1996 through 2008. All patients were previously untreated for H. pylori and were enrolled in the study to assess primary resistance to the three antibiotics.

RESULTS

The overall primary resistance to clarithromycin, amoxicillin and minocycline were 16.4%, (577/3521), 0.03% (1/3521) and 0.06% (2/3521), respectively. From 1996 through 2004, the resistance rate to clarithromycin increased gradually to approximately 30% and then it remained without marked fluctuation since 2004. Analysis by gender showed a significant increase (p < .0001) in resistance rate to clarithromycin among females (217/1057, 20.6%) compared to males (360/2467, 14.6%). Analysis by age, disclosed significantly (p < .0001) higher resistance rate to clarithromycin in patients of more than 65-years-old compared to the younger population.

CONCLUSIONS

The resistance rate of H. pylori infection to clarithromycin in Japan has increased gradually to approximately 30% from 1996 through 2004, and remained unchanged since 2004. Elderly and females were at high risk of having resistance to clarithromycin. Our results suggested that the level of clarithromycin resistance in Japan has now risen to the point where it should no longer be used as empiric therapy.

Triple or quadruple tetracycline-based therapies versus standard triple treatment for Helicobacter pylori treatment

BACKGROUND

Our aim was to compare lansoprazole-tetracycline-metranidazole (LTM) as first-line treatment with the classical lansoprazole-amoxicillin-clarithromycin (LAC) and bismuth-containing quadruple treatments.

PATIENTS AND METHODS

This prospective, single-center, randomized study included 464 consecutive Helicobacter pylori-positive patients with dyspeptic symptoms. A total of 415 patients completed the study. The patients were allocated into 4 study groups using random sampling numbers as follows-LAC group: lansoprazole 30 mg twice daily, amoxicillin 1000 mg twice daily, and clarithromycin 500 mg twice daily for 14 days; BLTM group: bismuth subcitrate 300 mg 4 times a day, lansoprazole 30 mg twice daily, tetracycline 500 mg 4 times a day, and metronidazole 500 mg twice daily for 10 days; RBLTM group: ranitidine bismuth citrate 400 mg twice daily, lansoprazole 30 mg twice daily, tetracycline 500 mg 4 times a day, and metronidazole 500 mg twice daily for 10 days; and LTM group: lansoprazole 30 mg twice daily, tetracycline 500 mg 4 times a day, and metronidazole 500 mg twice daily for 10 days.

RESULTS

The per protocol H. pylori eradication rate in LAC, BLTM, RBLTM, and LTM groups were 37 of 104 (35.6%), 56 of 102 (54.9%), 67 of 104 (64.4%), and 63 of 105 (60%), respectively. The intention-to-treat eradication rate was 37 of 113 (32.7%) in LAC, 56 of 119 (47.1%) in BLTM, 67 of 117 (57.3%) in RBLTM, and 63 of 115 (54.8%) in LTM group. The BLTM, RBLTM, and LTM treatment groups achieved a significantly better eradication rate than the LAC treatment group (P < 0.001). There was not any significant statistical difference between the groups of BLTM, RBLTM, and LTM.

CONCLUSION

LTM treatment group achieved a significantly better eradication rate than the LAC treatment group. The success ratio of LTM therapy is comparable with quadruple bismuth-based treatments.

Single nucleotide polymorphism of interleukin-1beta associated with Helicobacter pylori infection in immune thrombocytopenic purpura

To examine the role of genetic factors in development of immune thrombocytopenic purpura (ITP) in association with Helicobacter pylori infection, gene polymorphisms within the loci for human leukocyte antigen class II, interleukin (IL)-1beta (-511), tumor necrosis factor-beta (+252), immunoglobulin (Ig)G1 heavy chain (+643), and Igkappa light chain (+573) were determined in 164 adults with ITP and 75 healthy controls. Of these gene polymorphisms, the IL-1beta (-511) T allele was less frequently detected in H. pylori-infected than in H. pylori-uninfected (58% vs 81%, P = 0.01, odds ratio = 0.31) ITP patients diagnosed before age 50. These findings suggest that a single nucleotide polymorphism within the IL-1beta (-511) may affect susceptibility to early-onset ITP associated with H. pylori infection.

Identification and molecular characterization of triple- and quadruple-resistant Helicobacter pylori clinical isolates in Germany

OBJECTIVES

The aim of this study was to estimate the frequency of triple- and quadruple-resistant Helicobacter pylori isolated in Germany, to characterize those isolates molecular genetically and to identify risk factors for the development of multiresistance.

METHODS

Antimicrobial susceptibility to metronidazole, clarithromycin, amoxicillin, tetracycline, ciprofloxacin/levofloxacin and rifampicin in 1118 clinical isolates obtained between July 2006 and December 2007 was tested by the Etest method. For patients harbouring triple- or quadruple-resistant strains (n = 169), data on prior eradication therapies and underlying diseases were collected and evaluated. A select number of quadruple- and triple-resistant strains were examined for resistance-mediating mutations in their 23S rRNA, 16S rRNA, gyrA and rpoB genes, respectively.

RESULTS

From 1118 clinical isolates, 13.4% (n = 150) showed phenotypic resistance to metronidazole, clarithromycin and quinolones and 0.9% (n = 10) to metronidazole, clarithromycin and rifampicin; one isolate exhibited resistance to clarithromycin, quinolones and rifampicin. In eight isolates (0.7%), we detected phenotypic quadruple resistance to metronidazole, clarithromycin, quinolones and rifampicin or tetracycline. Triple- and quadruple-resistant strains harboured resistance-associated mutations in their 23S rRNA, 16S rRNA, gyrA or rpoB genes and were nearly exclusively isolated from patients who had already been unsuccessfully treated on multiple occasions.

CONCLUSIONS

We show that more than 15% of H. pylori strains isolated from routine samples in the German National Reference Centre are resistant to three or more antimicrobials and identified prior unsuccessful eradication therapies as a key factor for the development of multiresistance. Our data emphasize the need for further comprehensive surveillance studies monitoring the role of treatment regimens in antimicrobial resistance in H. pylori.

Virulence factor genotypes of Helicobacter pylori affect cure rates of eradication therapy

The cure rates of Helicobacter pylori infection by using a combination of a proton pump inhibitor (PPI) and antimicrobial agents are mainly influenced by bacterial susceptibility to antimicrobial agents and the magnitude of acid inhibition during the treatment. Currently used empirical triple therapies do not reliably produce a > or =80% cure rate on an intention-to-treat basis. Therefore, tailored regimens based on relevant microbiological findings and pharmacogenomics are recommended for attaining an acceptable > or =95% cure rate. Recently, virulence factors of H. pylori, such as cagA and vacA, are reported to be major factors determining the cure rates. Individuals infected with strains with cagA-negative and vacA s2 genotypes have significantly increased risk of eradication failure of H. pylori infection. These virulence factors enhance gastric mucosal inflammation and are associated with the development of peptic ulcer and gastric cancer. H. pylori virulence factors induce proinflammatory cytokines, such as interleukin (IL)-1, IL-8, and tumor necrosis factor (TNF)- which influence mucosal inflammation and/or gastric acid secretion. When physicians select an H. pylori eradication regimen with an acceptable cure rate, they might need to consider H. pylori virulence factors, especially cagA and vacA.

Therapy for Helicobacter pylori infection can be improved: sequential therapy and beyond

As with other bacterial infections, successful treatment of Helicobacter pylori infections depends on the use of antibacterial agents to which the organism is susceptible. In this article, we use the proposed report card grading scheme (i.e. grade A, B, C, D, F) for the outcome of clinical trials, where intention-to-treat cure rates >95% = A, 90-95% = B, 85-89% = C, 81-84% = D and <81% = F. The goal of therapy is to consistently cure >95% of patients (e.g. provide grade A results). Like tuberculosis, H. pylori infections are difficult to cure and successful treatment generally requires the administration of several antibacterial agents simultaneously. Duration of therapy is also important and depends upon whether resistance is present; 14 days is often best. With few exceptions, worldwide increasing macrolide resistance now undermines the effectiveness of the legacy triple therapy (e.g. a proton pump inhibitor [PPI], clarithromycin and amoxicillin) and, in most areas, cure rates have declined to unacceptable levels (e.g. grade F). The development of sequential therapy was one response to this problem. Sequential therapy has repeatedly been shown in head-to-head studies to be superior to legacy triple therapy. Sequential therapy, as originally described, is the sequential administration of a dual therapy (a PPI plus amoxicillin) followed by a Bazzoli-type triple therapy (a PPI plus clarithromycin and tinidazole) and has been shown to be especially useful where there is clarithromycin resistance. However, the cure rates of the original sequential treatment are grade B and can probably be further improved by changes in dose, duration or administration, such as by continuing the amoxicillin into the triple therapy arm. The sequential approach may also be more complicated than necessary, based on the fact that the same four drugs have also been given concomitantly (at least nine publications with >700 patients) as a quadruple therapy with excellent success. This article discusses the approach to therapy in the modern era where antimicrobial resistance is an increasing problem and legacy triple therapy is no longer an acceptable initial choice. Methods to achieve acceptable eradication rates (e.g. grade A or B results) are discussed and, specifically, sequential therapy is considered both conceptually and practically. Suggestions are provided regarding how sequential therapy might be improved to become a grade A therapy as well as how to identify situations where it can be expected to yield unacceptable results. New uses for current drugs are discussed and suggestions for subsequent randomized comparisons to overcome phenotypic and genotypic resistance are given. We propose a change in focus from comparative studies (designed to prove that a new therapy is superior to a known inferior therapy) to demanding that efficacious therapies meet or exceed a pre-specified level of success (i.e. grade A or B result). To do so, coupled with less concern about the effect of recommendations on the pharmaceutical industry, should provide clinicians with much higher quality information, and improve the quality of medical care and recommendations regarding treatment. Ultimately, there is little or no justification for comparative testing that includes an arm with known unacceptably low results. H. pylori gastritis is an infectious disease and should be approached and treated as such.

Novel insight in the association between salmonellosis or campylobacteriosis and chronic illness, and the role of host genetics in susceptibility to these diseases

We studied the role of host genetics in the susceptibility to severe Salmonella and Campylobacter infections and chronic sequelae of these infections. Participants of a previous case-control study were sent a buccal swab kit and a questionnaire about occurrence of chronic sequelae. Single nucleotide polymorphisms (SNPs) in the TLR4 (rs4986790), IFNG (rs2430561 and rs1861493), STAT1 (rs1914408), IL1B (rs16944), NRAMP (SLC11A1 rs2276631), JUN (rs11688) and VDR (rs10735810) genes were determined. In total, 687 controls, 457 Campylobacter cases and 193 Salmonella cases participated. None of the SNPs were associated with Campylobacter or Salmonella infections. None of the participants developed Guillain-Barré, Miller-Fisher or Reiter's syndrome. Reactive arthritis occurred in 5% and 2% of cases and controls, respectively. Campylobacter cases more frequently experienced gastroenteritis episodes than controls. Campylobacter or Salmonella infection in women, use of proton pump inhibitors and an SNP in the IFNG gene were independent risk factors for reactive arthritis. Another SNP in the IFNG gene and use of proton pump inhibitors were risk factors for recurrent episodes of gastroenteritis. In conclusion, reactive arthritis and recurrent gastroenteritis episodes are common after infection and host genetic factors play a role in susceptibility to these long-term health effects.

Treatment strategy to eradicate Helicobacter pylori infection: impact of pharmacogenomics-based acid inhibition regimen and alternative antibiotics

The eradication rates of Helicobacter pylori by the triple therapy consisting of a proton pump inhibitor (PPI) and two antimicrobial agents are mainly influenced by bacterial susceptibility to antimicrobial agents and magnitude of acid inhibition during the treatment with a PPI. Acid inhibition during the treatment is affected by the dosing schemes of acid inhibitory drugs (i.e., PPI), genotypes of drug-metabolizing enzymes (i.e., CYP450 2C19), drug transporters (i.e., multi-drug resistant transporter-1) and inflammatory cytokines (i.e., IL-1 beta). Modification of dosing schedules of a PPI, such as frequent PPI dosing and concomitant dosing with a histamine 2-receptor antagonist, could overcome these genetics-related differences in therapeutic effectiveness. For attaining higher eradication rates, the tailored regimen based on the relevant pharmacogenomics is preferable.

Evidence that the degree and duration of acid suppression are related to Helicobacter pylori eradication by triple therapy

BACKGROUNDS AND AIMS

Eradication rates of Helicobacter pylori by a proton pump inhibitor-based triple therapy depend on CYP2C19 genotype status. We investigated whether gastric acid inhibition during an eradication therapy would influence the eradication rates attained by the triple therapy.

METHODS

Thirty-two patients with H. pylori infection underwent the first-line triple therapy with lansoprazole 30 mg, amoxicillin 750 mg, and clarithromycin 400 mg b.i.d. for 1 week. In all 32 patients, the 24-hour intragastric pH monitoring was performed on day 6 during the treatment period.

RESULTS

The intention-to-treat-based eradication rate by the first-line therapy was 75.0% (24/32, 95%CI: 56.60-88.54%). In patients with successful eradication, the median 24-hour pH was 6.4 (range; 5.0-7.6), which was significantly higher than that in patients without eradication [5.2 (2.2-6.2), p = .0131]. The median percentage time of pH < 4.0 during 24-hour postdose in patients with eradication [0.5% (0.0-31.6%)] was significantly shorter than that in patients without eradication [26.7% (6.0-72.2%), p = .0017]. These parameters for acid inhibition significantly differed among the different CYP2C19 genotype groups. When the percentage time of pH < 4.0 and 24-hour pH were attained < 10% and > 6.0, respectively, during the eradication treatment, the majority of patients could eradicate H. pylori infection, irrespective of the bacterial susceptibility to clarithromycin.

CONCLUSIONS

The sustained intragastric pH > 4.0 for a longer postdose time appears to be required for a successful eradication of H. pylori with lansoprazole and acid-labile antibiotics.

A report card to grade Helicobacter pylori therapy

Helicobacter pylori causes a serious bacterial infectious disease, and the expectations of therapy should reflect this fact. Increasing antibiotic resistance, especially to clarithromycin, has significantly undermined the effectiveness of legacy triple therapy consisting of a proton pump inhibitor, clarithromycin, and amoxicillin. Current cure rates are consistently below 80% intention-to-treat, the accepted threshold separating acceptable from unacceptable treatment results. Grading clinical studies into effectiveness categories using prespecified criteria would allow clinicians to objectively identify and compare regimens. We offer a therapy report card similar to that used to grade the performance of school children. The intention-to-treat cure rate categories are: F or unacceptable ( 80%), D or poor (81-84%), C or fair (85-89%), B or good (90-95%), and A or excellent (95-100%). The category of "excellent" is based on the cure rates expected with other prevalent bacterial infectious diseases. We propose that only therapies that score "excellent" (grade = A) should be prescribed. Regimens scoring as B or "good" can be used if "excellent" results are not obtainable. In most regions legacy triple therapy should be abandoned as unacceptable. Quadruple therapy and sequential therapy are reasonable alternatives for initial therapy.

Dual therapy with high doses of rabeprazole and amoxicillin versus triple therapy with rabeprazole, amoxicillin, and metronidazole as a rescue regimen for Helicobacter pylori infection after the standard triple therapy

BACKGROUNDS AND AIMS

Development of safe and effective rescue regimens for eradication failure of Helicobacter pylori infection by standard regimens is an urgent task. We designed the prospective study to compare the efficacy of two rescue regimens after eradication failure by the standard triple therapy.

METHODS

One hundred and thirty-two patients in whom eradication of H. pylori infection failed initial triple therapy with lansoprazole 30 mg b.i.d, amoxicillin 750 mg b.i.d. and clarithromycin 400 mg b.i.d. for 1 week were randomized to either the 1-week triple therapy with rabeprazole 10 mg b.i.d., amoxicillin 750 mg b.i.d., and metronidazole 250 mg b.i.d. (RAM) or the 2-week dual therapy with rabeprazole 10 mg q.i.d. and amoxicillin 500 mg q.i.d. (RA). Eradication of H. pylori was judged by (13)C-urea breath test 1 month later.

RESULTS

The intention-to-treat and per-protocol-based eradication rates were 92.4% (95% CI: 83.2-97.5) and 95.3% (95% CI: 86.9-99.0) for the RAM therapy and 90.9% (95% CI: 81.2-96.6) and 93.8% (95% CI: 84.8-98.3), respectively, for the RA therapy (P > 0.2 for both). No clinically recognizable adverse events were observed with either regimen.

CONCLUSION

RA as well as RAM therapy are safe and effective rescue regimens for H. pylori infection after eradication failure by the standard triple therapy.

Determination of mutations of the 23S rRNA gene of Helicobacter pylori by allele specific primer-polymerase chain reaction method

BACKGROUND AND AIMS

Susceptibility to clarithromycin of Helicobacter pylori (H. pylori) is caused by single nucleotide polymorphisms (SNPs) of the 23SrRNA gene. Allele specific primer-polymerase chain reaction (ASP-PCR) is one of the methods for determining SNPs, which can measure SNPs easily within a short period by PCR amplification alone without digestion with restriction enzymes. The aim of the present study was to develop the ASP-PCR assay for determining SNPs at positions 2,142 and 2,143 of the 23S rRNA gene of H. pylori.

METHODS

In total, 112 patients with H. pylori infection based on positive results of a rapid urease test (RUT) were enrolled in the study. Thirty-five had failed to eradicate H. pylori by a clarithromycin-based regimen. DNA was extracted from the RUT-positive gastric tissue samples. SNPs from adenine to guanine at positions 2,142 and 2,143 of the 23S rRNA of H. pylori (A2,142G and A2,143G) were determined by the ASP-PCR method. Minimum inhibitory concentrations (MICs) of clarithromycin for H. pylori were also measured.

RESULTS

Forty-nine of 112 patients were infected with wild-type strains of H. pylori. Thirty-nine patients were infected with strains with A2,143G mutations. Twenty-three patients were infected with both wild-type strains and those with A2,143G mutations. Only one patient was infected with the strain with A2,142G mutation. H. pylori strains with A2,143G or A2,142G mutation had significantly higher MICs for clarithromycin.

CONCLUSION

The ASP-PCR assay for 23S rRNA mutation of H. pylori is a useful method to detect clarithromycin-resistant strains of H. pylori easily.

Eradication rate of Helicobacter pylori according to genotypes of CYP2C19, IL-1B, and TNF-A

BACKGROUND

Lansoprazole, amoxicillin, and clarithromycin are commonly used drugs for eradication of Helicobacter pylori (H. pylori). A few studies reported that the eradication rate was influenced by the functional polymorphism of CYP2C19, whose product metabolizes proton pomp inhibitors including lansoprazole.

METHODS

This study examined the eradication rate among 67 participants in the polymorphism study who visited Daiko Medical Center, Nagoya University from July 2004 to October 2005. The participants aged 20 to 69 years were classified into three group according to CYP2C19 genotype; rapid metabolizers (RM) with *1*1 genotype, intermediate metabolizers (IM) with *1*2 or *1*3 genotype, and poor metabolizers (PM) with *2*2, *2*3, or *3*3 genotype. For the genotype classification, G681A (681G for *1 and 681A for *2) and G636A (636G for *1 and 636A for *3) were genotyped by PCR with confronting two-pair primers (PCR-CTPP). They were also genotyped for IL-1B T-31C and TNF-A T-1031C by a duplex PCR-CTPP.

RESULTS

The eradication rate was 70.0% for RM, 93.9% for IM, and 85.7% for PM. The difference in the rate between RM and IM+PM was statistically significant (p=0.025). The eradication rate was highest for those with IL-1B -31CC; the p value was marginal among the whole subjects (chi2=3.78, p=0.05) and not significant among the RM group (chi2=1.60, p=0.21). The genotypes of TNF-A T-1031C had no associations with the eradication rate. But among the RM group, the odd ratio (OR) of the TNF-A CT for the eradication rate relative to TT was marginally reduced (OR=0.05, 95% confidence interval, 0.002-1.19).

CONCLUSIONS

The present study confirmed the low eradication rate for RM. The reproduced finding provides evidence that the CYP2C19 genotype is useful to predict the success of the treatment. For the RM group, alternative regimens expected to be with a higher eradication rate will be recommended, especially to those with the TNF-A -1031C allele.

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori infection

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori.

Pharmacogenomics and individualized drug therapy

Pharmacogenetics deals with inherited differences in the response to drugs. The best-recognized examples are genetic polymorphisms of drug-metabolizing enzymes, which affect about 30% of all drugs. Loss of function of thiopurine S-methyltransferase (TPMT) results in severe and life-threatening hematopoietic toxicity if patients receive standard doses of mercaptopurine and azathioprine. Gene duplication of cytochrome P4502D6 (CYP2D6), which metabolizes many antidepressants, has been identified as a mechanism of poor response in the treatment of depression. There is also a growing list of genetic polymorphisms in drug targets that have been shown to influence drug response. A major limitation that has heretofore moderated the use of pharmacogenetic testing in the clinical setting is the lack of prospective clinical trials demonstrating that such testing can improve the benefit/risk ratio of drug therapy.

Papel del polimorfismo genético CYP2C19 en los efectos adversos a fármacos y en el riesgo para diversas enfermedades

There are a great number of polymorphic genes in the human genome. Many of them codify enzymes that metabolizes drugs and xenobiotic agents, including carcinogens. Among the better known of them, there are a number of isozymes of the microsomal oxidative system (CYP3A4, CYP2C9, CYP2C19 y CYP2D6). This article reviews the following issues: a) frequency of presentation of the "poor metabolizer" genotype and/or phenotype for substrates of CYP2C19; b) role of CYP2C19 polymorphism on the metabolism of some drugs (mephenytoine and other antiepileptic drugs, proton pump inhibitors, several antidepressants and anxyolitics, the antimalaria aggent proguanyl, and propranolol, among others, use this metabolic pathway), and c) possible role of CYP2C19 polymorphism in the risk for development of neoplasia and other diseases (systemic lupus erythematosus, psoriasis, hip osteonecrosis, Alzheimer's disease, amyotrophic lateral sclerosis, essential tremor).

Third-line rescue therapy for Helicobacter pylori infection

H pylori gastric infection is one of the most prevalent infectious diseases worldwide. The discovery that most upper gastrointestinal diseases are related to H pylori infection and therefore can be treated with antibiotics is an important medical advance. Currently, a first-line triple therapy based on proton pump inhibitor (PPI) or ranitidine bismuth citrate (RBC) plus two antibiotics (clarithromycin and amo-xicillin or nitroimidazole) is recommended by all consensus conferences and guidelines. Even with the correct use of this drug combination, infection can not be eradicated in up to 23% of patients. Therefore, several second line therapies have been recommended. A 7 d quadruple therapy based on PPI, bismuth, tetracycline and metronidazole is the more frequently accepted. However, with second-line therapy, bacterial eradication may fail in up to 40% of cases. When H pylori eradication is strictly indicated the choice of further treatment is controversial. Currently, a standard third-line therapy is lacking and various protocols have been proposed. Even after two consecutive failures, the most recent literature data have demonstrated that H pylori eradication can be achieved in almost all patients, even when antibiotic susceptibility is not tested. Different possibilities of empirical treatment exist and the available third-line strategies are herein reviewed.

What is potent acid inhibition, and how can it be achieved?

The clinical response to antisecretory treatment correlates directly with the degree of inhibition of acid secretion achieved. Acid inhibition able to maintain the intragastric pH at a value greater than 4 for at least 16 h/day seems to heal even the most refractory acid-related diseases. It has also been shown that the degree of inhibition of acid secretion in response to antisecretory treatment depends on the genetic characteristics of the patient and on the presence of Helicobacter pylori infection. A possible definition of potent (or profound) acid inhibition is, therefore, the achievement of the aforementioned level of control of acid secretion regardless of patient characteristics or of the presence of H. pylori infection. Antisecretory drugs differ in their ability to reach potent acid inhibition. As far as the comparative efficacy of different drugs for inhibiting acid secretion is concerned, proton pump inhibitors are more efficient in inhibiting gastric acid secretion than histamine (H2) receptor antagonists. Among the different proton pump inhibitors, esomeprazole 40 mg/day exhibits greater antisecretory potency than the others at standard doses. Rabeprazole 20 mg/day and lansoprazole 30 mg/day exhibit a more rapid onset of action than omeprazole 20 mg/day or pantoprazole 40 mg/day.

Gastroduodenal disease, Helicobacter pylori, and genetic polymorphisms

Over the past 20 years, there has been marked progress in our understanding of the role of genetic and environmental factors in the etiology of gastroduodenal disease. Helicobacter pylori infection now is recognized to be the most important environmental factor for both noncardia gastric cancer and peptic ulcer disease. The likelihood of the infection resulting in significant disease depends on genetic polymorphisms influencing the virulence of the organism. However, the specific pattern of disease induced by the infection is determined to a great extent by genetic polymorphisms in the host that govern the local gastric immune response elicited. Genetic factors also are important in the treatment of gastroduodenal diseases. Polymorphisms of host CYP2C19 influence the pharmacokinetics and clinical efficacy of proton pump inhibitor therapy.

Poor metabolizer genotype status of CYP2C19 is a risk factor for developing gastric cancer in Japanese patients with Helicobacter pylori infection

BACKGROUND

Cytochrome P450 2C19 (CYP2C19) polymorphism has been associated with the development of lung, liver or oesophageal cancer by detoxification of carcinogen(s) or activation of procarcinogen(s).

AIM

To clarify the association between CYP2C19 polymorphisms and gastric cancer development in Japanese. Methods : We determined CYP2C19 genotypes (CYP2C19*1, *2 and *3) in 111 Helicobacter pylori-positive patients with gastric cancer and 315 H. pylori-positive controls without gastric cancer consisting of patients with gastritis only or peptic ulcer. Frequencies of CYP2C19 genotypes and serum pepsinogen I and II levels, a biomarker of gastric atrophy, in the gastric cancers and controls were compared.

RESULTS

Frequencies of homozygous extensive metabolizers, heterozygous extensive metabolizers and poor metabolizers were 31.5%, 42.3% and 26.2% in the gastric cancers and 38.1%, 47.0% and 14.9% in the controls, respectively (P = 0.046). Poor metabolizers were associated with an increased risk for developing gastric cancer with the age- and sex-adjusted odds ratio (OR) of 1.975 [95% confidence interval (CI): 1.068-3.649], especially for diffuse type (OR: 3.385, CI: 1.187-9.648). There is no significant association between CYP2C19 genotypes and serum pepsinogen I level or pepsinogen I/II ratios, although serum pepsinogen I level in gastric cancers were significantly decreased.

CONCLUSIONS

In H. pylori-positive Japanese, poor metabolizers of CYP2C19 appear to be at an increased risk for developing gastric cancer, especially diffuse type, and may require an intensive follow-up for scrutinizing possible gastric cancer development.

Helicobacter pylori antibiotic resistance in Iran

AIM: To examine the frequency of antibiotic resistance in Iranian Helicobacter pylori (H pylori) strains isolated from two major hospitals in Tehran.

METHODS: Examination of antibiotic resistance was performed on 120 strains by modified disc diffusion test and PCR-RFLP methods. In addition, in order to identify the possible causes of the therapeutic failure in Iran, we also determined the resistance of these strains to the most commonly used antibiotics (metronidazole, amoxicillin, and tetracycline) by modified disc diffusion test.

RESULTS: According to modified disc diffusion test, 1.6% of the studied strains were resistant to amoxicillin, 16.7% to clarithromycin, 57.5% to metronidazole, and there was no resistance to tetracycline. Of the clarithromycin resistant strains, 73.68% had the A2143G mutation in the 23S rRNA gene, 21.05% A2142C, and 5.26% A2142G. None of the sensitive strains were positive for any of the three point mutations. Of the metronidazole resistant strains, deletion in rdxA gene was studied and detected in only 6 (5%) of the antibiogram-based resistant strains. None of the metronidazole sensitive strains possessed rdxAgene deletion.

CONCLUSION: These data show that despite the fact that clarithromycin has not yet been introduced to the Iranian drug market as a generic drug, nearly 20% rate of resistance alerts toward the frequency of macrolide resistance strains, which may be due to the widespread prescription of erythromycin in Iran. rdxA gene inactivation, if present in Iranian H pylori strains, may be due to other genetic defects rather than gene deletion.

Effect of concomitant dosing of famotidine with lansoprazole on gastric acid secretion in relation to CYP2C19 genotype status

BACKGROUND

Famotidine increases Helicobacter pylori-eradication rates by a triple lansoprazole/amoxicillin/clarithromycin therapy in patients with the rapid extensive metabolizer genotype of CYP2C19.

AIM

To determine the effect of famotidine on the gastric acid inhibition by lansoprazole in relation to CYP2C19 genotypes.

METHODS

Twenty healthy volunteers with different CYP2C19 genotypes--consisting of six rapid extensive metabolizers, nine intermediate metabolizers and five poor metabolizers--underwent three 7-day courses with placebo, lansoprazole 30 mg twice daily, and lansoprazole 30 mg twice plus famotidine 20 mg twice daily. Lansoprazole was dosed after breakfast and dinner. Famotidine was dosed after lunch and at bedtime. Intragastric pH monitoring was performed for 24 h on day 7 of each course.

RESULTS

With placebo, no difference was observed in intragastric pH profiles among the three CYP2C19 genotype groups. With lansoprazole 30 mg twice daily, the median of 24-h intragastric pH in poor metabolizers (6.1) was significantly higher than those of rapid extensive metabolizers (4.5) and intermediate metabolizers (5.0), respectively (P = 0.0176 and 0.0388), whereas with lansoprazole 30 mg twice and famotidine 20 mg twice daily, the medians were 5.4, 5.7, and 6.1, respectively (not significant).

CONCLUSION

Acid inhibition by lansoprazole was influenced by CYP2C19 genotype status. This influence was offset by the concomitant use of famotidine.

New once-daily, highly effective rescue triple therapy after multiple Helicobacter pylori treatment failures: a pilot study

BACKGROUND

Helicobacter pylori treatment failure is a growing problem in daily practice.

AIM

To determine the efficacy of the combination of rabeprazole, levofloxacin and furazolidone as a rescue therapy.

METHODS

Duodenal ulcer patients previously submitted, without success, to at least two H. pylori treatment regimens were included. Gastroscopy (urease test, histological examination and culture) and (13)C-urea breath test were performed. All patients received a combination of rabeprazole 20 mg, levofloxacin 500 mg and furazolidone 200 mg (two tablets) administered in a single dose in the morning for 10 days. Clinical examination and a new (13)C-urea breath test were performed 90 days after therapy.

RESULTS

Twelve patients (eight females and four males), mean age 43 (30-58) years were included. Two patients failed to complete the treatment because of nausea and vomiting. Ten patients completed the study and took all the medications as advised. Culture was obtained in six patients: 100 and 83% of the samples were sensitive to furazolidone and levofloxacin, respectively. Per-protocol and intention-to-treat eradication rates were 100 and 83% (P = 0.019).

CONCLUSIONS

the combination of rabeprazole, levofloxacin and furazolidone in a single daily dose for 10 days constitutes a highly-effective and low-cost alternative as a third-line therapy in patients infected with H. pylori.

Molecular biology methods for the characterization of Helicobacter pylori infections and their diagnosis

Helicobacter pylori infects approximately half of the human population; however, the outcome of infection is affected by many factors, including strain and host genotype characteristics and bacterial density within the stomach. Many molecular methods have been developed to provide information with respect to these characteristics. Methods that provide results within 24 h of endoscopy may be used to develop individualized treatment that is more effective, results in fewer side effects, cuts costs,decreases the number of treatment failures and results in the development of fewer antibiotic-resistant H. pylori strains.

Concomitant dosing of famotidine with a triple therapy increases the cure rates of Helicobacter pylori infections in patients with the homozygous extensive metabolizer genotype of CYP2C19

BACKGROUND

Proton-pump inhibitors, such as lansoprazole, are metabolized in the liver by CYP2C19 and cannot inhibit acid sufficiently in homozygous extensive metabolizers of CYP2C19.

AIM

To examine whether famotidine would increase the cure rates of Helicobacter pylori infection by a standard triple therapy.

METHODS

A total of 177 H. pylori-positive patients were randomly assigned to either lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week (LCA group; n = 89) or famotidine 20 mg b.d., lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week (FLCA group; n = 88). Famotidine was administered after lunch and before sleep, and the others were after breakfast and dinner. CYP2C19 genotypes were determined by a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

In the LCA group, the eradication rates for homozygous extensive metabolizers, heterozygous extensive metabolizers, and poor metabolizers were 63%, 87%, and 100%, respectively (P = 0.014). Those in the FLCA group were 85%, 85%, and 100%, respectively (N.S.). The cure rate for homozygous extensive metabolizers in the FLCA group was significantly higher than that in the LCA group (P = 0.035).

CONCLUSION

Famotidine improves the cure rate of H. pylori infection by a triple therapy in CYP2C19 homozygous extensive metabolizers patients.