Clarithromycin-resistance and point mutations in the 23S rRNA gene in Helicobacter pylori isolates from Japan

Assessment for antibiotic resistance in Helicobacter pylori: A practical and interpretable machine learning model based on genome-wide genetic variation

Helicobacter pylori (H. pylori) antibiotic resistance poses a global health threat. Accurate identification of antibiotic resistant strains is essential for the control of infection. In the present study, our goal is to leverage the whole-genome data of H. pylori to develop practical and interpretable machine learning (ML) models for comprehensive antibiotic resistance assessment. A total of 296 H. pylori isolates with genome-wide data were downloaded from the Bacterial and Viral Bioinformatics Resource Center (BV-BRC) and the National Center for Biotechnology Information (NCBI) databases. By training ML models on feature sets of single nucleotide polymorphisms from SNP calling (SNPs-1), antibiotic-resistance SNP annotated by the Comprehensive Antibiotic Resistance Database (SNPs-2), gene presence or absence (GPA), we generated predictive models for four antibiotics and multidrug-resistance (MDR). Among them, the models that combined SNPs-1, SNPs-2, and GPA data demonstrated the best performance, with the eXtreme Gradient Boosting (XGBoost) consistently outperforming others. And then we utilized the SHapley Additive exPlanations (SHAP) method to interpret the ML models. Furthermore, a free web application for the MDR model was deployed to the GitHub repository (https://H.pylori/MDR/App/). Our study demonstrated the promise of employing whole-genome data in conjunction with ML algorithms to forecast H. pylori antibiotic resistance. In the future, the application of this approach for predicting H. pylori antibiotic resistance would hold the potential to mitigate the empiric administration.

Optimizing Helicobacter pylori Treatment: An Updated Review of Empirical and Susceptibility Test-Based Treatments

As the rate of discovery of drug-resistant Helicobacter pylori cases increases worldwide, the relevant societies have updated their guidelines for primary eradication regimens. A promising strategy against drug-resistant H. pylori is tailored therapy based on the results of an antibiotic susceptibility test; however, it is difficult to apply this strategy to all cases. Although culture-based antibiotic susceptibility tests can assess resistance to any antimicrobial agent, their greatest disadvantage is the time required to draw a conclusion. In contrast, molecular-based methods, such as polymerase chain reaction, can rapidly determine the presence of resistance, although a single test can only test for one type of antimicrobial agent. Additionally, the limited availability of facilities for molecular-based methods has hindered their widespread use. Therefore, low-cost, minimally invasive, simple, and effective primary regimens are needed. Several studies have compared the efficacy of the latest primary eradication regimens against that of tailored therapies, and their results have shaped guidelines. This article reviews the latest research on empirical and tailored treatments for H. pylori infections. Evidence for the superiority of tailored therapy over empirical therapy is still limited and varies by region and treatment regimen. A network meta-analysis comparing different empirical treatment regimens showed that vonoprazan triple therapy provides a superior eradication effect. Recently, favorable results towards vonoprazan dual therapy have been reported, as it reached eradication levels similar to those of vonoprazan triple therapy. Both vonoprazan dual therapy and tailored therapy based on antibiotic susceptibility tests could contribute to future treatment strategies.

Bismuth-Based Quadruple Therapy versus Metronidazole-Intensified Triple Therapy as a First-Line Treatment for Clarithromycin-Resistant Helicobacter pylori Infection: A Multicenter Randomized Controlled Trial

Background/Aims

Clarithromycin resistance is a main factor for treatment failure in the context of Helicobacterpylori infection. However, the treatment regimen for clarithromycin-resistant H. pylori infection has not yet been determined. We aimed to compare the efficacy and cost-effectiveness of 14-day bismuth-based quadruple therapy versus 14-day metronidazole-intensified triple therapy for clarithromycin-resistant H. pylori infection with genotypic resistance.

Methods

This was a multicenter, randomized, controlled trial. A total of 782 patients with H. pylori infection examined using sequencing-based clarithromycin resistance point mutation tests were recruited between December 2018 and October 2020 in four institutions in Korea. Patients with significant point mutations (A2142G, A2142C, A2143G, A2143C, and A2144G) were randomly assigned to receive either 14-day bismuth-based quadruple therapy (n=102) or 14-day metronidazole-intensified triple therapy (n=99).

Results

The overall genotypic clarithromycin resistance rate was 25.7% according to the sequencing method. The eradication rate of 14-day bismuth-based quadruple therapy was not significantly different in the intention-to-treat analysis (80.4% vs 69.7%, p=0.079), but was significantly higher than that of 14-day metronidazole-intensified triple therapy in the per-protocol analysis (95.1% vs 76.4%, p=0.001). There were no significant differences in the incidence of side effects. In addition, the 14-day bismuth-based quadruple therapy was more cost-effective than the 14-day metronidazole-intensified triple therapy.

Conclusions

Fourteen-day bismuth-based quadruple therapy showed comparable efficacy with 14-day metronidazole-intensified triple therapy, and it was more cost-effective in the context of clarithromycin-resistant H. pylori infection.

Helicobacter pylori Eradication According to Sequencing-Based 23S Ribosomal RNA Point Mutation Associated with Clarithromycin Resistance

BACKGROUND/AIMS

Clarithromycin resistance in Helicobacter pylori is associated with point mutations in the 23S ribosomal RNA (rRNA) gene. We investigated the point mutations in the 23S rRNA genes of patients with clarithromycin-resistant H. pylori and compared the H. pylori eradication rates based on the point mutations.

METHODS

A total of 431 adult patients with H. pylori infection were recruited in Kangdong Sacred Heart Hospital in 2017 and 2018. Patients who did not have point mutations related to clarithromycin resistance and/or had clinically insignificant point mutations were treated with PAC (proton pump inhibitor, amoxicillin, clarithromycin) for seven days, while patients with clinically significant point mutations were treated with PAM (proton pump inhibitor, amoxicillin, metronidazole) for seven days. H. pylori eradication rates were compared.

RESULTS

Sequencing-based detection of point mutations identified four mutations that were considered clinically significant (A2142G, A2142C, A2143G, A2143C). The clarithromycin resistance rate was 21.3% in the overall group of patients. A2143G was the most clinically significant point mutation (84/431, 19.5%), while T2182C was the most clinically insignificant point mutation (283/431, 65.7%). The overall H. pylori eradication rate was 83.7%, and the seven-day PAM-treated clarithromycin-resistance group showed a significantly lower eradication rate than the seven-day PAC-treated nonresistance group (ITT; 55.4% (51/92) vs. 74.3% (252/339), p = 0.001, PP; 66.2% (51/77) vs. 88.4% (252/285), p = 0.0001).

CONCLUSIONS

There were significantly lower eradication rates in the patients with clarithromycin-resistant H. pylori when treated with PAM for seven days. A future study comparing treatment regimens in clarithromycin-resistant H. pylori-infected patients may be necessary.

Efficacy of tailored therapy for Helicobacter pylori eradication based on clarithromycin resistance and survey of previous antibiotic exposure: A single-center prospective pilot study

BACKGROUND

As the prevalence of antibiotic resistance is increasing, the effectiveness of traditional Helicobacter pylori (H pylori) therapies is gradually declining. We aimed to evaluate the efficacy of tailored therapy (dual priming oligonucleotide [DPO]-based multiplex PCR) and previous antibiotic exposure survey predicting for antibiotic resistance.

MATERIALS AND METHODS

Patients with H pylori infection who did not receive previous treatment were enrolled. The patients were divided into four groups (no resistance [NR] group, clarithromycin resistance [CLA-R] group, metronidazole-resistant [MET-R] group, and CLA- and MET-resistant [Dual-R] group) based on the results of dual priming oligonucleotide (DPO) polymerase chain reaction (PCR) and previous antibiotic exposure survey, and they were treated with tailored therapy based on antibiotic susceptibility.

RESULTS

Consecutive patients were distributed in the NR (n = 36, 70.6%), CLA-R (n = 9, 17.6%), and suspected MET-R (n = 6, 11.8%) group. The overall intention-to-treat/per-protocol eradication rate (ITT/PP) was 92.2%/94.0%. In the subgroup analysis, the ITT and PP of the NR, CLA-R, and MET-R groups were 94.4%/94.4%, 77.8%/87.5%, and 100.0%/100.0%, respectively. Total of 31 patients in all subgroups were evaluated for antibiotic resistance; five (16.1%), two (6.5%), and three (9.7%) participants showed CLA, MET, and dual resistance in culture-based susceptibility test. Compared with culture-based MIC test, the accuracy of DPO-based multiplex PCR in determining CLA resistance was 90.3%, while the accuracy of survey in determining MET resistance was only 77.4%.

CONCLUSION

A tailored therapy based on DPO-PCR and history of previous antibiotic use is useful in clinical practice and well correlated with culture-based susceptibility test.

Usefulness of detection of clarithromycin-resistant Helicobacter pylori from fecal specimens for young adults treated with eradication therapy

BACKGROUND

To prevent Helicobacter pylori infection in the younger generation, it is necessary to investigate the prevalence of antibiotic-resistant H. pylori.

OBJECTIVE

The aim of this study was to evaluate the method of PCR-based sequencing to detect clarithromycin (CAM) resistance-associated mutations using fecal samples as a noninvasive method.

METHODS

DNA extracted from fecal specimens and isolates from gastric biopsy specimens were collected from patients with H. pylori infection. Antibiotic resistance to CAM was analyzed by molecular and culture methods. The detection rates of CAM resistance-associated mutations (A2142C or A2143G) were compared before and after eradication therapy.

RESULTS

With CAM resistance of H. pylori evaluated by antibiotic susceptibility test as a gold standard, the sensitivity and the specificity of gene mutation detection from fecal DNA were 80% and 84.8%, respectively. In contrast, using DNA of isolated strains, the sensitivity and the specificity were 80% and 100%. Of the seven cases in which eradication was unsuccessful by triple therapy including CAM, CAM-resistant H. pylori, and resistance-associated mutations were detected in three cases, CAM-resistant H. pylori without the mutation was detected in two patients, and resistance-associated mutation was only detected in one patient.

CONCLUSION

PCR-based sequencing to detect CAM resistance-associated mutations using isolates or fecal samples was useful for finding antibiotic-resistant H. pylori infection. Although the specificity of the detection from fecal samples compared with antibiotic susceptibility testing was lower than that from isolates, this fecal detection method is suitable especially for asymptomatic subjects including children. Further improvement is needed before clinical application.

Helicobacter pylori from Peptic Ulcer Patients in Uganda Is Highly Resistant to Clarithromycin and Fluoroquinolones: Results of the GenoType HelicoDR Test Directly Applied on Stool

Background

Around 70–90% of peptic ulcer disease (PUD) is due to Helicobacter pylori and requires treatment with antimicrobials to which these bacteria are susceptible. Common H. pylori diagnostic tests do not provide drug susceptibility data. Using the GenoType HelicoDR PCR test designed for gastric biopsies for simultaneous detection of H. pylori and its resistance to clarithromycin (CLA)/fluoroquinolones (FLQ), we present evidence for stool as an optional test specimen and also provide data on prevalence of H. pylori resistance to CLA and FLQ in Uganda.

Methods

Stool from 142 symptomatic PUD patients at three hospitals in Kampala was screened for H. pylori using a rapid antigen test. The GenoType HelicoDR test was run on all H. pylori antigen positives to determine PCR positivity and resistance to CLA/FLQ.

Results

Thirty-one samples (22%) were H. pylori antigen positive, and 21 (68%) of these were H. pylori PCR positive. Six of the 21 (29%) were resistant to CLA and eight to FLQ (42%), while two gave invalid FLQ resistance results.

Conclusion

Stool is a possible specimen for the GenoType HelicoDR test for rapid detection of H. pylori and drug resistance. In Uganda, Helicobacter pylori is highly resistant to CLA and FLQ.

Microfluidics: innovative approaches for rapid diagnosis of antibiotic-resistant bacteria

The emergence of antibiotic-resistant bacteria has become a major global health concern. Rapid and accurate diagnostic strategies to determine the antibiotic susceptibility profile prior to antibiotic prescription and treatment are critical to control drug resistance. The standard diagnostic procedures for the detection of antibiotic-resistant bacteria, which rely mostly on phenotypic characterization, are time consuming, insensitive and often require skilled personnel, making them unsuitable for point-of-care (POC) diagnosis. Various molecular techniques have therefore been implemented to help speed up the process and increase sensitivity. Over the past decade, microfluidic technology has gained great momentum in medical diagnosis as a series of fluid handling steps in a laboratory can be simplified and miniaturized on to a small platform, allowing marked reduction of sample amount, high portability and tremendous possibility for integration with other detection technologies. These advantages render the microfluidic system a great candidate to be developed into an easy-to-use sample-to-answer POC diagnosis suitable for application in remote clinical settings. This review provides an overview of the current development of microfluidic technologies for the nucleic acid based and phenotypic-based detections of antibiotic resistance.

Characterization of 23S rRNA domain V mutations in gastric biopsy patients from the eastern Amazon

Resistance of Helicobacter pylori to clarithromycin is characterised by simple point mutations in the 23S ribosomal RNA (rRNA) gene and is responsible for the majority of cases of failure to eradicate this bacterium. In this paper, we characterised the variability of the 23S rRNA gene in biopsies of patients with gastric pathologies in the eastern Amazon (Northern Region of Brazil) using PCR and sequencing. A total of 49 sequences of H. pylori strains were analysed and of those, 75.6% presented nucleotide substitutions: A2142G (3.3%), T2182C (12.9%), G2224A (6.45%), T2215C (61.3%), A2192G (3.3%), G2204C (6.4%) and T2221C (6.4%). Of the mutations identified, four are known mutations related to cases of resistance and 16.1% are not yet described, revealing a high prevalence of mutations in the H. pylori 23S rRNA gene among the strains circulating in the in the eastern Amazon. The high prevalence in individuals with gastric pathologies in the Northern Region of Brazil demonstrates the need for characterising the profile of these strains to provide correct therapy for patients, considering that mutations in this gene are normally associated with resistance to the primary medication used in controlling H. pylori infection.

Potent bactericidal constituents from Mallotus philippinensis against clarithromycin and metronidazole resistant strains of Japanese and Pakistani Helicobacter pylori

In the quest for potent anti-Helicobacter pylori agents, we found 70% EtOH extract of Mallotus philippinensis (LAM.) MUELL. (MPM) with strong bactericidal activity at the concentration of 15.6-31.2 mg/l against eight H. pylori strains. Further fractionation and purification of 70% EtOH extract of MPM led to the isolation of 5 compounds, namely 5,7-dihydroxy-8-methyl-6-prenylflavanone (1), 3'-prenylrubranine (2), red compound (3), isorottlerin (4), and rottlerin (5) which were elucidated on the basis of nuclear magnetic resonance and mass spectroscopy. Among the isolated compounds, rottlerin exhibited most potent bactericidal activity with minimum bactericidal concentration (MBC) value of 3.12-6.25 mg/l against several clinical H. pylori isolates including Japanese and Pakistani strains, nine clarithromycin resistant (CR), and seven metronidazole resistant (MR) strains. Minimum inhibitory concentration (MIC) values of CR (8->256 mg/l) and MR (>256 mg/l) strains were analyzed by E test. Moreover, the clarithromycin resistant strains were evaluated for A2143G and A2144G point mutations of 23s rRNA gene to correlate the MBC values with mutation type. Our results revealed the potent in vitro anti-H. pylori activity of MPM and rottlerin, specially against CR and MR strains, which could be gainfully utilized for the development of novel antimicrobials to prevent H. pylori related disorders.

Who's Winning the War? Molecular Mechanisms of Antibiotic Resistance in Helicobacter pylori

The ability of clinicians to wage an effective war against many bacterial infections is increasingly being hampered by skyrocketing rates of antibiotic resistance. Indeed, antibiotic resistance is a significant problem for treatment of diseases caused by virtually all known infectious bacteria. The gastric pathogen Helicobacter pylori is no exception to this rule. With more than 50% of the world's population infected, H. pylori exacts a tremendous medical burden and represents an interesting paradigm for cancer development; it is the only bacterium that is currently recognized as a carcinogen. It is now firmly established that H. pylori infection is associated with diseases such as gastritis, peptic and duodenal ulceration and two forms of gastric cancer, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. With such a large percentage of the population infected, increasing rates of antibiotic resistance are particularly vexing for a treatment regime that is already fairly complicated; treatment consists of two antibiotics and a proton pump inhibitor. To date, resistance has been found to all primary and secondary lines of antibiotic treatment as well as to drugs used for rescue therapy.

Modified allele-specific primer-polymerase chain reaction method for analysis of susceptibility of Helicobacter pylori strains to clarithromycin

BACKGROUND AND AIM

Most clarithromycin-resistant strains of Helicobacter pylori have a mutation from adenine (A) to guanine (G) at position 2142 or 2143 of the 23S rRNA gene. Our aim in this study was to develop a polymerase chain reaction (PCR)-based assay that could determine these mutations in a single reaction tube.

METHODS

We designed the forward primer FP2143G and the reverse primer RP2142G, which specifically anneal with the 2143G- and 2142G-mutated sequences, respectively, of the 23S rRNA gene of H. pylori. We also designed the forward primer FP-1 and reverse primer RP-1 upstream and downstream from the positions 2142 and 2143, respectively, to distinguish the wild-type A2142G and A2143G mutations from each other by amplicon sizes. DNA was extracted from 292 gastric tissue samples positive for rapid urease test, and the DNA underwent the PCR reaction. The results were compared with minimum inhibitory concentrations (MIC) for clarithromycin.

RESULTS

Helicobacter pylori strains with A2142G, A2143G and wild type could be distinguished by amplicon sizes by a single PCR reaction. The genotyping results were correlated well with the MIC values for clarithromycin. The median MIC for clarithromycin of the wild-type strains was <0.015 microg/mL. Those of strains with 2142G or 2143G were > or =1.0 microg/mL.

CONCLUSION

Our new PCR-based assay for 23S rRNA mutations of H. pylori is a useful method for detecting clarithromycin-resistant strains of H. pylori easily.

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.

Helicobacter pylori infection rate in patients with nontuberculous mycobacteriosis who are on longterm combination chemotherapy of clarithromycin and rifampicin

Clarithromycin resistance in Helicobacter pylori has increased the incidence of eradication failure. Clarithromycin is a key drug in the current treatment regimens for H. pylori infection, and it is also used for nontuberculous mycobacteriosis (NTM). The rate of H. pylori infection in 15 patients with NTM who were on longterm clarithromycin, rifampicin, and other drug therapy was examined, using the [(13)C] urea breath test. H. pylori was detected in 5 of the 15 patients (33.3%), which was significantly lower than the prevalence of H. pyloriin subjects who had routine upper gastrointestinal endoscopy in Japan (P = 0.0006). Thus, H. pylori resistance to clarithromycin is suggested to be low in patients with longterm administration, and the possibility exists of a combination of clarithromycin and rifampicin as a second-line therapy for the eradiation of H. pylori.

Relation of CagA seropositivity to cagPAI phenotype and histological grade of gastritis in patients with Helicobacter pylori infection

AIM

Infection with Helicobacter pylori (H pylori) possessing the cag pathogenicity island (PAI) has been associated with severe clinical outcome and CagA-antibody has been used to indicate cagPAI-positive infection. The aim of this study was to examine the accuracy of CagA seropositivity to indicate the virulence of the cagPAI in Japan.

METHODS

Sixty isolates of H pylori cultured from gastric biopsies were examined by polymerase chain reaction assays for the presence of cagA, cagE and VirD4. Anti-CagA IgG antibody in matching sera was tested by both ELISA and immunoblot assay. Histological grade of gastritis was graded according to the updated Sydney System.

RESULTS

Amongst 53 patients infected with cagA+/cagE+/VirD4+ strain, 38 were CagA seropositive. There were four patients infected with strains possessing incomplete cagPAI. Two out of three patients with cagA+/cagE-/VirD4- infection were CagA seropositive, while a patient with cagA-/cagE+/VirD4+ infection was CagA seronegative. Accuracy of ELISA to predict bacterial possession of cagA was 61.7% whereas 58.3% for cagE and VirD4. The immunoblot assay showed relatively higher sensitivity and showed better accuracy. The lower grade of gastric mucosal inflammatory infiltration was seen in false CagA-seronegative patients.

CONCLUSION

Some serodiagnosis does not seem to have enough accuracy to indicate virulence of cagPAI, particularly in infection of strains with incomplete cagPAI. The degree of gastric mucosal inflammation may affect the results of CagA serodiagnosis.

T2182C mutation in 23S rRNA is associated with clarithromycin resistance in Helicobacter pylori isolates obtained in Bangladesh

Twelve clarithromycin-resistant (MIC, > or = 1 microg/ml) Helicobacter pylori isolates were analyzed for point mutations in the 23S rRNA gene. Sequence analysis of all of the resistant isolates revealed a T-to-C transition mutation at position 2182. Transformation experiments confirmed that a single T-to-C transition mutation at position 2182 is associated with clarithromycin resistance.

Second-line treatment of Helicobacter pylori infection after dilution agar methods and PCR-RFLP analysis

BACKGROUND

After unsuccessful first-line treatment of Helicobacter pylori infection, the percentage of clarithromycin-resistant strains has been reported as between 30% and 70% in Japan and other countries. A high prevalence of clarithromycin-resistant strains is reported to be associated with eradication failure.

AIM

We examined antibiotic susceptibility testing using a combination of dilution agar methods with PCR-restriction fragment length polymorphism (RFLP) analysis.

METHODS

We enrolled 41 patients in whom first-line treatment with LAC (lansoprazole, amoxycillin and clarithromycin) was unsuccessful. Endoscopic biopsied specimens were used to examine antibiotic susceptibility to clarithromycin by dilution agar methods. PCR-RFLP analysis was performed to determine the presence of point mutations, which are primarily responsible for resistance to clarithromycin.

RESULTS

Clarithromycin-resistance rate after failure of the LAC regimen was 73.2%. Drug susceptibilities of three strains obtained by PCR-RFLP analysis were different from those by dilution agar methods. One strain with MIC values to clarithromycin of 0.05 micro g/mL had a point mutation, A2144G. This strain was not eradicated by repeating LAC, but was eradicated by substituting metronidazole for clarithromycin.

CONCLUSIONS

Dilution agar methods should be combined with PCR-RFLP analysis before second-line eradication to increase the accuracy of clarithromycin-susceptibility testing and to improve eradication efficacy.

Characteristics and trends of clarithromycin-resistant Helicobacter pylori isolates in Japan over a decade

Clarithromycin has been administered to patients in Japan since 1991. Clarithromycin-resistant Helicobacter pylori strains have been on the rise in Japan. We obtained H. pylori isolates between 1989 and 2000 and examined mutations of the 23S rRNA gene, which are closely associated with clarithromycin resistance. Isolates were obtained from 356 patients with H. pylori infection treated at the Hiroshima University. Sixty-one of the patients received clarithromycin-based H. pylori eradication therapy. Mutations of the 23S rRNA gene were examined by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) followed by sequencing analysis. Mutant strains were found in 42 of the 356 patients (11.8%). The prevalence of mutant strains increased from 0 to 20.4% during the 12-year study period. The prevalence increased to more than 10% by 1995 and then to more 20% after 1999. The H. pylori eradication rate was significantly higher in patients with wild-type strains than in patients with mutant strains (72.0 vs. 36.4%, p = 0.024). Our data indicate that clarithromycin-resistant H. pylori strains have increased rapidly since 1995 and that the effectiveness of clarithromycin-based H. pylori eradication therapies may soon be compromised. Other new therapies may be necessary as first-line treatments in Japan.

Eradication of Helicobacter pylori by 7-day triple-therapy regimens combining pantoprazole with clarithromycin, metronidazole, or amoxicillin in patients with peptic ulcer disease: results of two double-blind, randomized studies

AIM

To compare the short-term (7-day) safety and efficacy of two triple-therapy regimens using pantoprazole with those of two dual-therapy regimens (one with pantoprazole and one without), for Helicobacter pylori eradication in patients with peptic ulcer disease.

METHODS

H. pylori infection was identified by rapid urease (CLOtest), and confirmed by histology and culture. Patients were enrolled into one of two randomized, double-blind, multicenter, parallel-group studies. In study A, patients received oral pantoprazole 40 mg, clarithromycin 500 mg, and metronidazole 500 mg (PCM); pantoprazole, clarithromycin and amoxicillin 1000 mg (PCA); or pantoprazole and clarithromycin (PC). In study B, patients received PCM, PCA, PC, or clarithromycin and metronidazole without pantoprazole (CM). Treatments were given twice daily for 7 days. H. pylori status after therapy was assessed by histology and culture at 4 weeks after completing the course of study treatment. Modified intent-to-treat (MITT; each study: n = 424, n = 512) and per-protocol (PP; each study: n = 371, n = 454) populations were analyzed. The MITT population comprised all patients whose positive H. pylori status was confirmed by culture and histology; the PP population comprised patients who also complied with > or = 85% of study medication doses.

RESULTS

A total of 1016 patients were enrolled. Cure rates among patients with clarithromycin-susceptible H. pylori strains were 82 and 86% for PCM, and 72 and 71% for PCA, in studies A and B, respectively. Cure rates among patients with metronidazole-susceptible H. pylori strains were 82 and 87% for PCM, and 71 and 69% for PCA, in studies A and B, respectively. The combined eradication rates observed with the PCM regimen were superior to those of all other regimens tested. Side-effects were infrequent and mild.

CONCLUSIONS

PCM had the highest overall eradication rate in these two studies examining 7-day treatment regimens. All regimens were safe and well tolerated.

Is antimicrobial susceptibility testing necessary before second-line treatment for Helicobacter pylori infection?

BACKGROUND

An antimicrobial susceptibility test for Helicobacter pylori before second-line treatment is often performed, although whether the test is truly necessary remains unknown.

PATIENTS AND METHODS

Eighty-two patients with H. pylori infection for whom first-line treatment with a 1-week proton pump inhibitor/amoxicillin-clarithromycin (AC) regimen had failed were randomly assigned to two groups: those having or not having the susceptibility test before re-treatment. The cure rates for these two groups were compared.

RESULTS

Five of the 82 patients were excluded from the analysis. For 38 patients in the susceptibility-test group, we used what we considered the best regimen based on susceptibility testing: 10 patients [no resistance to clarithromycin (CAM)] received the lansoprazole-amoxicillin-clarithromycin regimen, 22 patients [19 CAM resistant, metronidazole (MNZ) susceptible; three failure of culture] were given the lansoprazole-amoxicillin-metronidazole (LAM) regimen, and six patients (both MNZ and CAM resistant) received dual therapy with omeprazole (OPZ) and amoxicillin (AMOX) in which the OPZ dose was determined by the CYP2C19 gene polymorphism. For 39 patients in the group with no susceptibility testing, LAM regimens were prescribed. The intention-to-treat (ITT)-based cure rates in the groups with and without susceptibility testing were 81.6% (95% confidence interval; 66-92%) and 92.4% (79-98%), respectively, and there was no significant difference between these two groups.

CONCLUSION

Susceptibility testing is not necessarily required before second-line therapy if the first-line treatment has been performed using proton pump inhibitor/AC regimens.