Genotypic resistance in Helicobacter pylori strains correlates with susceptibility test and treatment outcomes after levofloxacin- and clarithromycin-based therapies. Antimicrob Agents Chemother. 2011;55:1123-1129. [PMID: 21189342 DOI: 10.1128/aac.01131-10]

Molecular testing-guided therapy versus susceptibility testing-guided therapy in first-line and third-line Helicobacter pylori eradication: two multicentre, open-label, randomised controlled, non-inferiority trials

BACKGROUND

Helicobacter pylori infection is an important causal factor of gastric cancer and peptic ulcer disease and is associated with immune thrombocytopenic purpura and functional dyspepsia. In H pylori strains, point mutations in the 23S rRNA and gyrA genes are associated with clarithromycin resistance and levofloxacin resistance, respectively. Whether the efficacy of molecular testing-guided therapy is non-inferior to that of susceptibility testing-guided therapy for H pylori eradication is unclear. Therefore, we aimed to compare the efficacy and safety of molecular testing-guided therapy and traditional culture-based susceptibility testing-guided therapy in first-line and third-line treatment of H pylori infection.

METHODS

We did two multicentre, open-label randomised trials in Taiwan. In trial 1 (done at seven hospitals), treatment-naive individuals infected with H pylori who were aged 20 years or older were eligible for study inclusion. In trial 2 (done at six hospitals), individuals aged 20 years or older who failed treatment after two or more eradication therapies for H pylori infection were eligible for enrolment. Eligible patients were randomly assigned (1:1) to receive either molecular testing-guided therapy or susceptibility testing-guided therapy. The randomisation sequence was generated by computer using permuted block randomisation with a block size of 4. All investigators were masked to the randomisation sequence. Clarithromycin and levofloxacin resistance were determined by agar dilution test for measuring minimum inhibitory concentrations in the susceptibility testing-guided therapy group, and by PCR and direct sequencing for detection of 23S rRNA and gyrA mutations in the molecular testing-guided therapy group. Study participants received clarithromycin sequential therapy, levofloxacin sequential therapy, or bismuth quadruple therapy according to the resistance status to clarithromycin and levofloxacin. The 13C-urease breath test was used to determine the status of H pylori infection at least 6 weeks after eradication therapy. The primary outcome was the eradication rate by intention-to-treat analysis. The frequency of adverse effects was analysed in patients with available data. The prespecified margins for non-inferiority were 5% for trial 1 and 10% for trial 2. The trials are ongoing for post-eradication follow-up and registered with ClinicalTrials.gov, NCT03556254 for trial 1, and NCT03555526 for trial 2.

FINDINGS

Between March 28, 2018, and April 23, 2021, 560 eligible treatment-naive patients with H pylori infection were recruited and randomly assigned to the molecular testing-guided therapy group or the susceptibility testing-guided therapy group in trial 1. Between Dec 28, 2017, and Oct 27, 2020, 320 eligible patients with refractory H pylori infection were recruited and randomly assigned to the molecular testing-guided therapy group or the susceptibility testing-guided therapy group in trial 2. 272 men and 288 women were recruited for trial 1, and 98 men and 222 women were recruited for trial 2. In first-line H pylori treatment, infection was eradicated in 241 (86%, 95% CI 82-90) of 280 patients in the molecular testing-guided therapy group and 243 (87%, 83-91) of 280 patients in the susceptibility testing-guided therapy group by intention-to-treat analysis (p=0·81). In third-line H pylori treatment, infection was eradicated in 141 (88%, 83-93) of 160 patients in the molecular testing-guided therapy group and 139 (87%, 82-92) of 160 patients in the susceptibility testing-guided therapy group by intention-to-treat analysis (p=0·74). The difference in the eradication rate between the molecular testing-guided therapy group and the susceptibility testing-guided therapy group was -0·7% (95% CI -6·4 to 5·0; non-inferiority p=0·071) in trial 1 and 1·3% (-6·0 to 8·5; non-inferiority p=0·0018 in trial 2 by intention-to-treat analysis. We found no difference in adverse effects across both treatment groups in trial 1 and trial 2.

INTERPRETATION

Molecular testing-guided therapy was similar to susceptibility testing-guided therapy in first-line therapy and non-inferior to susceptibility testing guided therapy in third-line treatment of H pylori infection, supporting the use of molecular testing-guided therapy for H pylori eradication.

FUNDING

Ministry of Science and Technology of Taiwan, and Centre of Precision Medicine of the Higher Education Sprout Project by the Ministry of Education of Taiwan.

Multiple amino acid substitutions in penicillin-binding protein-1A confer amoxicillin resistance in refractory Helicobacter pylori infection

BACKGROUND

Amoxicillin resistance in Helicobacter pylori is mainly associated with mutations in penicillin-binding protein-1A (PBP-1A). However, the specific amino acid substitutions in PBP-1A that confer amoxicillin resistance in H. pylori remain to be investigated.

OBJECTIVE

This study aimed to investigate the molecular mechanism underlying amoxicillin resistance in patients with refractory H. pylori infection.

METHODS

Esophagogastroduodenoscopy (EGD) was performed in patients with persistent H. pylori infection after at least two courses of H. pylori eradication therapy between January-2018 to March-2021. Refractory H. pylori was cultured from the gastric biopsy specimens. Antibiotic susceptibility testing was conducted to determine the minimum inhibitory concentrations (MICs). Sequence analysis of pbp-1A was performed for amoxicillin-resistant strains.

RESULTS

Thirty-nine successfully cultured isolates were classified as refractory H. pylori isolates, and seventeen isolates were resistant to amoxicillin (MIC > 0.125 mg/L). Sequence analysis of resistant strains showed multiple mutations in the C-terminal region of PBP-1A that conferred amoxicillin resistance in H. pylori. However, the number of PBP-1A mutations did not correlate with the high MICs of amoxicillin-resistant isolates. Notably, some amino acid substitutions were identified in all Taiwanese isolates with history of eradication failure but not in published amoxicillin-susceptible strains, suggesting that the mutations may play a role in conferring antibiotic resistance to these strains.

CONCLUSIONS

Our results show that amoxicillin resistance in refractory H. pylori is highly correlated with numerous PBP-1A mutations that are strain specific. Continuous improvements in diagnostic tools, particularly molecular analysis approaches, can help to optimize current antimicrobial regimens.

Mutations Related to Antibiotics Resistance in Helicobacter pylori Clinical Isolates from Bangladesh

Current management of gastric inflammation involves the eradication of Helicobacter pylori. However, the effectiveness of commonly used antibiotics against H. pylori infection has decreased due to antibiotic resistance. Phenotypic-based diagnostics are laborious and finding the cause of resistance can be difficult. Therefore, early detection and understanding of the underlying mechanism of this resistance are necessary. This study evaluated the mutations in the genes related to the Antimicrobial Resistance (AMR) of the clinical isolates from Bangladeshi subjects. Whole-genome sequencing was performed on 56 isolates and the genes (such as pbp1a, rdxA, ribF, fur, gyrA, gyrB, 23S rRNA, and infB) were extracted. The reads were assembled, and the SNPs were extracted by the latest pipeline for antibiotic mutation analysis, ARIBA. The mutations and the association with the antibiotic phenotypes were evaluated using Fisher's exact test. In this study, the clarithromycin resistance rate was high, 39.3% (22/56), with the median MIC 24 mg/L ranging from 2 to 128 mg/L. The mutation of A2147G was significantly associated with resistance (p = 0.000018) but not in locus A2146G (p = 0.056). Levofloxacin also posed a high resistance. We observed that the mutation of D91N (but not D91Y) (p = 0.002) and N87K (p = 0.002) of gyrA was associated with levofloxacin resistance. Mutations in locus A343V (p = 0.041) of gyrB also showed a significant association. Meanwhile, in the pbp1a gene, several mutations might explain the resistance; they were G594fs (p = 0.036), K306R (p = 0.036), N562Y (p = 0.0006), and V45I (p = 0.018). The prevalence of metronidazole was exceptionally high (96.4%), and numerous mutations occurred in rdxA genes, including the truncation of genes. These results imply that the mutation in genes encoding the target protein of antibiotics remains the critical resistance mechanism in H. pylori.

Personalized Approach in Eradication of Helicobacter pylori Infection

The increase in antibiotic resistance to Helicobacter pylori (H. pylori) is associated with a decrease in the effectiveness of eradication therapy. Although some success has been achieved by adjusting therapeutic regimens according to local data on resistance to certain antibiotics, a new approach is needed to ensure a better therapeutic response. Tailored therapy, based on sensitivity tests to antibiotics, is increasingly proving to be a superior therapeutic option, even as a first-line therapy. Moreover, the recently published Maastricht VI guidelines emphasize utilizing a susceptibility-guided strategy in respect to antibiotic stewardship as the first choice for eradication therapy. In addition, polymerase chain reaction (PCR) technology is becoming a standard tool in the diagnosis of H. pylori infections through non-invasive testing, which further optimizes the eradication process. We provide a review regarding the current position of the individualized approach in eradication therapy and its future prospects. Based on novel understandings, the personalized approach is an effective strategy to increase the successful eradication of H. pylori infections.

Next-Generation Sequencing-Based Study of Helicobacter pylori Isolates from Myanmar and Their Susceptibility to Antibiotics

Evaluation of Helicobacter pylori resistance to antibiotics is crucial for treatment strategy in Myanmar. Moreover, the genetic mechanisms involved remain unknown. We aimed to investigate the prevalence of H. pylori infection, antibiotic resistance, and genetic mechanisms in Myanmar. One hundred fifty patients from two cities, Mawlamyine (n = 99) and Yangon (n = 51), were recruited. The prevalence of H. pylori infection was 43.3% (65/150). The successfully cultured H. pylori isolates (n = 65) were tested for antibiotic susceptibility to metronidazole, levofloxacin, clarithromycin, amoxicillin, and tetracycline by Etest, and the resistance rates were 80%, 33.8%, 7.7%, 4.6%, and 0%, respectively. In the multidrug resistance pattern, the metronidazole–levofloxacin resistance was highest for double-drug resistance (16/19; 84.2%), and all triple-drug resistance (3/3) was clarithromycin–metronidazole–levofloxacin resistance. Twenty-three strains were subjected to next-generation sequencing to study their genetic mechanisms. Interestingly, none of the strains resistant to clarithromycin had well-known mutations in 23S rRNA (e.g., A2142G, A2142C, and A2143G). New type mutation genotypes such as pbp1-A (e.g., V45I, S/R414R), 23S rRNA (e.g., T248C), gyrA (e.g., D210N, K230Q), gyrB (e.g., A584V, N679H), rdxA (e.g., V175I, S91P), and frxA (e.g., L33M) were also detected. In conclusion, the prevalence of H. pylori infection and its antibiotic resistance to metronidazole was high in Myanmar. The H. pylori eradication regimen with classical triple therapy, including amoxicillin and clarithromycin, can be used as the first-line therapy in Myanmar. In addition, next-generation sequencing is a powerful high-throughput method for identifying mutations within antibiotic resistance genes and monitoring the spread of H. pylori antibiotic-resistant strains.

Development and Validation of Multiplex Quantitative PCR Assay for Detection of Helicobacter pylori and Mutations Conferring Resistance to Clarithromycin and Levofloxacin in Gastric Biopsy

Aims and Objectives

More than half of the world's population is infected with Helicobacter pylori, which can cause chronic gastritis. WHO has regarded clarithromycin-resistant H. pylori as a high priority pathogen. Hence, accurate diagnosis and detection of clarithromycin- and levofloxacin-resistant H. pylori strains is essential for proper management of infection. The objective of this study was to develop and optimize multiplex quantitative PCR assay for detection of mutations associated with clarithromycin and levofloxacin resistance in H. pylori directly from the gastric biopsies.

Materials and Methods

Specific primers and probes were designed to amplify ureA and mutations in 23S rRNA and gyrA genes. Singleplex and triplex qPCR assays were optimized and the assay's sensitivities and specificities were determined. The optimized multiplex qPCR assay was performed on 571 gastric biopsies.

Results

In this study, 14.7% (84/571) of the gastric biopsies were positive for H. pylori by conventional methods and 23.8% (136/571) were positive by the ureA-qPCR with 96.4% sensitivity and 88.5% specificity, while the +LR and -LR were 8.72 and 0.04, respectively. The ureA-positive samples (n=136) were subjected to multiplex qPCR which detected A2142G and A2143G mutations in the 23S rRNA gene (20.6%, 28/136) conferring clarithromycin resistance and gyrA mutations N87K, N87I, D91N, and D91Y (11.8%, 16/136) leading to levofloxacin resistance. The sensitivity and specificity of qPCR of 23S rRNA gene were 100% and 98.7%, respectively, while 100% and 99.8% for qPCR of gyrA, respectively.

Conclusion

The effectiveness of this qPCR is that it is sensitive in detecting low bacterial load and will help in timely detection of clarithromycin- and levofloxacin-resistant strains, especially in case of mixed infections. Since it is culture independent, it can inform clinicians about antibiotics to be included in the first-line therapy, thereby improving the management of H. pylori infection at a much greater pace.

Treatment of Refractory Helicobacter pylori Infection-Tailored or Empirical Therapy

The treatment of refractory Helicobacter pylori remains challenging in clinical practice. Factors that should be considered in the treatment of refractory H. pylori infection include treatment length, dosage of antibiotics and proton pump inhibitors (PPIs), number of drugs, and the selection of appropriate antibiotics. Extending the treatment length of triple therapy and non-bismuth quadruple therapy to 14 days may increase the eradication rate compared with a shorter period (7 or 10 days). The use of a higher dose of PPIs or vonoprazan may also increase the efficacy of triple therapy. Four-drug therapy, including bismuth or non-bismuth quadruple therapies, usually achieve higher eradication rates than triple therapy. The addition of bismuth or metronidazole to levofloxacin-amoxicillin-PPI therapy may also increase the eradication rate. Therefore, four-drug therapies containing a higher dose of PPIs for 14 days are recommended in the third-line treatment setting for refractory H. pylori infection. The selection of appropriate antibiotics may be guided by susceptibility testing or empirically by medication history. Tailored therapy guided by susceptibility testing or genotypic resistance is recommended whenever possible. However, properly designed empirical therapy based on prior medication history (i.e., avoid the reuse of clarithromycin or levofloxacin empirically) is an acceptable alternative to tailored therapy after considering accessibility, cost, and the preference of the patient.

Antofloxacin-based bismuth quadruple therapy is safe and effective in Helicobacter pylori eradication: A prospective, open-label, randomized trial

BACKGROUND AND STUDY AIMS

The present study was designed to evaluate the safety, efficacy, and tolerability of antofloxacin-based bismuth quadruple therapy in Chinese patients with Helicobacter pylori infection.

PATIENTS AND METHODS

Total 290 patients with H. pylori infection were randomly and equally divided into two groups as per different bismuth quadruple therapies for 14 d: colloidal bismuth pectin 200 mg thrice a day, lansoprazole 30 mg twice a day, amoxicillin 1 g twice a day, and antofloxacin 200 mg once a day (ACLA group) or levofloxacin 500 mg once a day (LCLA group). Eradication was assessed with ¹³C-urea breath test 6 wk after treatment completion; the primary endpoint was the eradication rate by intention-to-treat (ITT) and per-protocol (PP) analyses. The minimum inhibitory concentration was measured with the PDM epsilometer test to assess the susceptibility of H. pylori strains on gastric biopsy specimens to antofloxacin and levofloxacin.

RESULTS

The eradication rates of H. pylori in the ACLA group were 93.8% and 97.8% for the ITT and PP analysis, respectively; these rates were significantly higher than those in the LCLA group, at 86.2% and 92.6%, respectively (p = 0.031 and 0.041, respectively). The total incidence of adverse events during the eradication therapy did not significantly differ between the ACLA and LCLA groups (31.7% vs. 37.9%%, p = 0.267), and the two groups displayed similar severity of adverse events (p = 0.156) and compliance rate (100% by ACLA vs. 97.8% by LCLA, p = 0.080). The eradication rate with the antofloxacin susceptible strains in the ACLA group was significantly higher than that with the resistant strains (99.2% vs. 66.7%, p = 0.045). Moreover, the eradication rate with the levofloxacin susceptible strains in the LCLA group was significantly higher than that with the resistant strains (95.3% vs. 80.0%, p = 0.013).

CONCLUSION

Antofloxacin is safe and effective for H. pylori eradication. Antofloxacin-based bismuth quadruple therapy could be an alternative treatment for H. pylori eradication.

Molecular Epidemiology and Antimicrobial Resistance of Clostridioides difficile in Hospitalized Patients From Mexico

Clostridioides difficile is a global public health problem, which is a primary cause of antibiotic-associated diarrhea in humans. The emergence of hypervirulent and antibiotic-resistant strains is associated with the increased incidence and severity of the disease. There are limited studies on genomic characterization of C. difficile in Latin America. We aimed to learn about the molecular epidemiology and antimicrobial resistance in C. difficile strains from adults and children in hospitals of México. We studied 94 C. difficile isolates from seven hospitals in Mexico City from 2014 to 2018. Whole-genome sequencing (WGS) was used to determine the genotype and examine the toxigenic profiles. Susceptibility to antibiotics was determined by E-test. Multilocus sequence typing (MLST) was used to determine allelic profiles. Results identified 20 different sequence types (ST) in the 94 isolates, mostly clade 2 and clade 1. ST1 was predominant in isolates from adult and children. Toxigenic strains comprised 87.2% of the isolates that were combinations of tcdAB and cdtAB (tcdA+/tcdB+/cdtA+/cdtB+, followed by tcdA+/tcdB+/cdtA-/cdtB-, tcdA-/tcdB+/cdtA-/ cdtB-, and tcdA-/tcdB-/cdtA+/cdtB+). Toxin profiles were more diverse in isolates from children. All 94 isolates were susceptible to metronidazole and vancomycin, whereas a considerable number of isolates were resistant to clindamycin, fluroquinolones, rifampicin, meropenem, and linezolid. Multidrug-resistant isolates (≥3 antibiotics) comprised 65% of the isolates. The correlation between resistant genotypes and phenotypes was evaluated by the kappa test. Mutations in rpoB and rpoC showed moderate concordance with resistance to rifampicin and mutations in fusA substantial concordance with fusidic acid resistance. cfrE, a gene recently described in one Mexican isolate, was present in 65% of strains linezolid resistant, all ST1 organisms. WGS is a powerful tool to genotype and characterize virulence and antibiotic susceptibility patterns.

Genomic Analysis of Antimicrobial Resistance Genotype-to-Phenotype Agreement in Helicobacter pylori

Antimicrobial resistance (AMR) in Helicobacter pylori is increasing and can result in treatment failure and inappropriate antibiotic usage. This study used whole genome sequencing (WGS) to comprehensively analyze the H. pylori resistome and phylogeny in order to characterize Israeli H. pylori. Israeli H. pylori isolates (n = 48) underwent antimicrobial susceptibility testing (AST) against five antimicrobials and WGS analysis. Literature review identified 111 mutations reported to correlate with phenotypic resistance to these antimicrobials. Analysis was conducted via our in-house bioinformatics pipeline targeting point mutations in the relevant genes (pbp1A, 23S rRNA, gyrA, rdxA, frxA, and rpoB) in order to assess genotype-to-phenotype correlation. Resistance rates of study isolates were as follows: clarithromycin 54%, metronidazole 31%, amoxicillin 10%, rifampicin 4%, and levofloxacin 2%. Genotype-to-phenotype correlation was inconsistent; for every analyzed gene at least one phenotypically susceptible isolate was found to have a mutation previously associated with resistance. This was also observed regarding mutations commonly used in commercial kits to diagnose AMR in H. pylori cases. Furthermore, 11 novel point mutations associated with a resistant phenotype were detected. Analysis of a unique set of H. pylori isolates demonstrates that inferring resistance phenotypes from WGS in H. pylori remains challenging and should be optimized further.

Secondary Antibiotic Resistance, Correlation between Genotypic and Phenotypic Methods and Treatment in Helicobacter pylori Infected Patients: A Retrospective Study

The aim of this study was to evaluate the secondary resistance in Helicobacter pylori (Hp) infected patients who had failed a first-line therapy, and to compare the genotypic tests performed directly on gastric samples with phenotypic tests performed on culture media. The eradication rate of patients treated with bismuth quadruple therapy (BQT) is also evaluated. A total of 80 positive specimens were retrospectively examined. Antibiotic susceptibility testing of Hp strains was performed by E-test, whereas a molecular commercially available method was used for detecting the mutations involved in clarithromycin and levofloxacin resistance. High resistance levels to metronidazole and clarithromycin (61.6% and 35%, respectively) and worrying resistance levels to levofloxacin (15%) were found phenotypically. Multiple resistance to two or three antibiotics was observed as well. The polymorphism A2143G on clarithromycin 23S rRNA gene was found in 34/80 (42.5%) isolates including 10 mixed infections (29%), whereas 28/80 (35%) strains were resistant phenotypically. Levofloxacin resistance corresponded to 30% by PCR and 15% by E-test (statistically significant, p < 0.05). The knowledge of clarithromycin and levofloxacin resistance is crucial to establish an appropriate therapy in different geographical areas. The genetic methods were superior to phenotypic techniques in the absence of live bacteria or for identifying mixed infections that may lead to a resistance underestimation. The BQT eradication rate was effective (90%).

Treatment of Helicobacter pylori infection and its long-term impacts on gut microbiota

The rising prevalence of antibiotic resistance and the long-term safety following eradication therapy are important issues in the management of Helicobacter pylori infection. The prevalence of clarithromycin, levofloxacin, and metronidazole resistance of H. pylori has increased to 21%, 27%, and 45%, respectively, in the Asia-Pacific region. Personalized treatment guided by susceptibility testing may provide a reliably excellent eradication rate in the first-line treatment but is costly and not widely available. Population-specific empirical therapy according to the local prevalence of antibiotic resistance may be an alternative strategy. Levofloxacin-based therapy and bismuth quadruple therapy are the recommended second-line rescue therapy. Susceptibility testing or genotypic resistance-guided therapy is the preferred treatment for refractory H. pylori infection, but empirical therapy may be an acceptable alternative. Eradication of H. pylori leads to short-term perturbation of gut microbiota. The diversity of gut microbiota can be restored months after eradication therapy, but the speed of recovery varies with regimens. The short-term increases of antibiotic resistance of Escherichia coli and Klebsiella pneumoniae may be restored to basal states months after H. pylori eradication. Future studies that apply in-depth sequencing, such as shotgun metagenomics sequencing, are needed to clarify whether the compositions of gut microbiota at the species level are fully restored.

Genotypic and Phenotypic Resistance to Clarithromycin in Helicobacter pylori Strains

Background: The increasing prevalence of antimicrobial resistance, together with the lack of novel treatment options, negatively affects successful eradication of Helicobacter pylori. The aim of this study was to investigate genetic mutations in the 23S rRNA genes, which is associated with clarithromycin resistance, and to determine the clinical impact of genotype on phenotypic antimicrobial resistance. Methods: A total of 46 H. pylori strains were obtained from 13 patients, before and after unsuccessful eradication with clarithromycin-based triple therapy. The phenotypic resistance of each H. pylori strain was determined by minimum inhibitory concentration against clarithromycin using the serial two-fold agar dilution method. The genomic sequences of 23S rRNA genes were identified through next-generation sequencing, and nucleotide variants were determined based on comparison with genome sequences of the reference strain H. pylori 26695. Results: Clarithromycin resistance was found in 9 of 13 subjects before treatment and all subjects after unsuccessful eradication. Whole-genome sequencing of the 23S rRNA genes detected 42 mutations on 40 nonidentical loci, including 2147A>G (formerly 2143A>G) and 2146A>G (formerly 2142A>G). All strains with clarithromycin-resistant phenotype had either 2147A>G or 2146A>G mutation. When comparing genotype and phenotype for clarithromycin resistance, there was a significant association between 2147A>G mutation and clarithromycin-resistant phenotype. Conclusions: All clarithromycin-resistant strains had either 2146A>G or 2147A>G mutation, suggesting that tests targeting these two mutations may be enough for the prediction of clarithromycin resistance in this population.

Susceptibility-guided bismuth quadruple therapies for resistant Helicobacter pylori infections

Increasing Helicobacter pylori resistance to antibiotics has ledthat molecular testing is appropriate as a sub to adoption of seven different bismuth quadruple therapies (BQT) in China without differentiation of first-line or second-line regimens. The objective of this study was to evaluate the efficacy of susceptibility-guided BQT for patients who had experienced previous treatment failures. A total of 133 patients was included and H. pylori was successfully cultured from 101 patients (75.9%) for subsequent antimicrobial susceptibility testing (AST). Based on the AST results, 88 patients completed one of five AST-guided 14-day BQT regimens: esomeprazole and bismuth colloidal pectin, along with either, amoxicillin and clarithromycin (EBAC), amoxicillin and levofloxacin (EBAL), amoxicillin and furazolidone (EBAF), amoxicillin and tetracycline (EBAT), or tetracycline and furazolidone (EBTF). H. pylori eradication rates were 100% for EBAC (5/5), EBAL (13/13), EBAF (14/14), and EBTF (43/43), but 76.9% for EBAT (10/13). The three patients that failed the EBAT regimen were all cured after subsequent treatment with the EBTF regimen. Our study demonstrates the excellent efficacy of the AST-guided BQT for referred H. pylori patients, and that the current EBAT regimen, used in clinics, needs to be optimized. In addition, 57 of the isolates were subjected to whole-genome sequencing. Analysis of the sequences revealed that point mutations in 23S rRNA correlated well with the phenotypic clarithromycin resistance with a concordance of 91.2%, while the concordance between phenotypic levofloxacin resistance and gyrA point mutations was 82.3%. This suggests that molecular testing is appropriate as a substitute for AST as a more rapid and cost-effective method for determining clarithromycin and levofloxacin resistance in Chinese patients.

Update on quinolone-containing rescue therapies for Helicobacter pylori infection

Third generation of quinolones, such as levofloxacin and moxifloxacin, -containing regimens are often used in second-line or rescue treatment of Helicobacter pylori infection. However, the increasing antibiotic resistance to quinolones affects the efficacies of quinolones-containing therapies in recent years. Therefore, there is a need to enhance the effectiveness of quinolones-containing therapies. Sitafloxacin, a fourth-generation quinolone, and vonoprazan, a novel potassium-competitive acid blocker, are now available as more effective treatment options. The aim of this paper is to summarize the current evidence of quinolone-containing therapies in rescue treatments, and to discuss the importance of drug sensitivity tests or analysis of gyrA mutation before treatments.

Characteristics of Helicobacter pylori antibiotic resistance: data from four different populations

Aims

To describe the characteristics of Helicobacter pylori (H. pylori) antibiotic resistance in clinical isolates from four populations.

Methods

In total, 1463 H. pylori strains were examined for antibiotic resistance. Among these strains, 804 were isolated from treatment-naïve adults, 133 from previously treated adults, 100 from treatment-naïve children and 426 from a population who participated in a health survey (age ≥ 40 years). The minimum inhibitory concentration was determined by the E-test method.

Results

In the treatment-naïve adult group, the resistance rates for metronidazole, clarithromycin, levofloxacin, amoxicillin, rifampicin and tetracycline were 78.4, 19.0, 23.3, 1.2, 1.7 and 2.3%, respectively. Compared with this group, the previously treated adult group had significantly higher resistance rates for metronidazole (99.2%), clarithromycin (58.3%) and levofloxacin (52.3%). In addition, the treatment-naïve children had a lower metronidazole resistance rate (46.0%) than the treatment-naïve adults. The resistance rate for clarithromycin was low in treatment-naïve patients with ages ranging from 10 to 24 years. For the strains isolated from the general population group, the resistance rates for metronidazole, clarithromycin, levofloxacin, amoxicillin, rifampicin and tetracycline were 78.6, 10.1, 25.1, 0.5, 2.1 and 0.9%, respectively. Compared with the treatment-naïve adult group, the general population group showed significant differences in clarithromycin resistance.

Conclusion

The resistance rates for metronidazole, clarithromycin and levofloxacin were high, especially in previously treated adults. Compared to those in treatment-naïve younger patients, the resistance rates for clarithromycin were significantly lower in treatment-naïve patients with ages ranging from 10 to 24 years and in the general population.

Histological changes in refractory Helicobacter pylori infection and its relationship with increased levels of resistance to antibiotics and therapeutic regimens: one-year follow-up

Eradication failure of Helicobacter pylori infection could play a causal role in progression of gastric disorders. In this study, infection with H. pylori was followed in gastric biopsies of symptomatic adult patients at two phases during 1-year period. Analyses were done to show association of therapeutic regimens with the refractory infection, changes in sequence types (STs) and minimum inhibitory concentration (MIC) values, and progression of histopathological changes. Infection with H. pylori was confirmed in 32.3% (57/170) of the patients. Persistent infection with H. pylori was confirmed in 14 out of the 25 patients (56%) who participated at the second phase of the study. A difference between primary and secondary resistance rates to clarithromycin (49% vs 64.3%), metronidazole (76.36% vs 100%), and ciprofloxacin (45% vs 57.1%) was detected. Although the re-emerged strains in patients with refractory infection did not show alteration in STs, their MIC₅₀ values showed twofold increases for clarithromycin and ciprofloxacin. While ciprofloxacin containing regimens were more successful, failure of metronidazole containing regimens was detected in 77% of the patients. Consequently, inappropriate medication has an impact on refractory H. pylori infection, which could cause to a rise in resistance levels to antibiotics and progression of pathological disorders.

Toward population specific and personalized treatment of Helicobacter pylori infection

In the face of rising prevalence of antibiotic resistance, susceptibility testing to provide personalized treatment is recommended prior to eradication therapy for Helicobacter pylori (H. pylori). Yet, population specific treatment according to the local prevalence of antibiotic resistance may be an alternative if susceptibility testing is not available. In this article, we reviewed the global prevalence of primary antibiotic resistance and the efficacies of commonly used regimens in antibiotic susceptible and resistance strains. We then constructed a model to predict the efficacies of these regimens and proposed an algorithm to choose the optimal first-line and rescue therapies according to the prevalence of antibiotic resistance. Clarithromycin-based therapy (triple, sequential, concomitant, and hybrid therapies) for 14 days remains the treatment of choice in regions with low clarithromycin resistance (≤15%) and bismuth quadruple therapy may be an alternative therapy. In regions with high clarithromycin resistance (> 15%), bismuth quadruple therapy is the treatment of choice and non-bismuth quadruple therapy may be an alternative. Either levofloxacin-based therapy or bismuth quadruple therapy may be used as second-line rescue therapy for patients fail after clarithromycin-based therapies, whereas levofloxacin-based therapy may be used for patients fail after bismuth quadruple therapy. Susceptibility testing or genotypic resistance should be determined after two or more eradication failures. However, empirical therapy according to prior medication history to avoid the empirical reuse of levofloxacin and clarithromycin may be an acceptable alternative after consideration of cost, patient preference, and accessibility. Rifabutin-based therapy for 14 days may serve as the fourth-line therapy. New antibiotics specific for H. pylori are highly anticipated.

Efficacies of Genotypic Resistance-Guided vs Empirical Therapy for Refractory Helicobacter pylori Infection

BACKGROUND & AIMS

We aimed to compare the efficacy of genotypic resistance-guided therapy vs empirical therapy for eradication of refractory Helicobacter pylori infection in randomized controlled trials.

METHODS

We performed 2 multicenter, open-label trials of patients with H pylori infection (20 years or older) failed by 2 or more previous treatment regimens, from October 2012 through September 2017 in Taiwan. The patients were randomly assigned to groups given genotypic resistance-guided therapy for 14 days (n = 21 in trial 1, n = 205 in trial 2) or empirical therapy according to medication history for 14 days (n = 20 in trial 1, n = 205 in trial 2). Patients received sequential therapy containing esomeprazole and amoxicillin for the first 7 days, followed by esomeprazole and metronidazole, with levofloxacin, clarithromycin, or tetracycline (doxycycline in trial 1, tetracycline in trial 2) for another 7 days (all given twice daily) based on genotype markers of resistance determined from gastric biopsy specimens (group A) or empirical therapy according to medication history. Resistance-associated mutations in 23S ribosomal RNA or gyrase A were identified by polymerase chain reaction with direct sequencing. Eradication status was determined by ¹³C-urea breath test. The primary outcome was eradication rate.

RESULTS

H pylori infection was eradicated in 17 of 21 (81%) patients receiving genotype resistance-guided therapy and 12 of 20 (60%) patients receiving empirical therapy (P = .181) in trial 1. This trial was terminated ahead of schedule due to the low rate of eradication in patients given doxycycline sequential therapy (15 of 26 [57.7%]). In trial 2, H pylori infection was eradicated in 160 of 205 (78%) patients receiving genotype resistance-guided therapy and 148 of 205 (72.2%) patients receiving empirical therapy (P = .170), according to intent to treat analysis. The frequencies of adverse effects and compliance did not differ significantly between groups.

CONCLUSIONS

Properly designed empirical therapy, based on medication history, is an acceptable alternative to genotypic resistance-guided therapy for eradication of refractory H pylori infection after consideration of accessibility, cost, and patient preference. ClinicalTrials.gov ID: NCT01725906.

Helicobacter pylori eradication in Mexico with a levofloxacin-based scheme versus standard triple therapy: Results from an open-label, randomized, noninferiority phase iiib trial

INTRODUCTION AND AIMS

Helicobacter pylori (H. pylori) infection remains the leading cause of several gastroduodenal diseases. Despite the fact that multiple antibiotic regimens have been used to change its associated morbidity and mortality, the prevalence of this bacterial infection continues to be disproportionately high worldwide, mainly due to antibiotic resistance. To assess the noninferiority efficacy and safety of 210-day triple regimens on H. pylori eradication, we evaluated clarithromycin 500mg, lansoprazole 30mg, and amoxicillin 1g, all bid (standard triple therapy or CLA, Group 1) vs. pantoprazole 80mg, levofloxacin 500mg and azithromycin 500mg, all od (PLA, Group 2). Both regimens were compared in treatment-naïve patients.

MATERIALS AND METHODS

An open label phase IIIb randomized and noninferiority trial comparing CLA vs. PLA was carried out for a 10-day period, within the time frame of June 2012 and March 2014. Eradication was verified with ¹³C-urea breath testing. Gastric biopsies were tested for fluorescence in situ hybridization (FISH)-clarithromycin resistance prior to any antibiotic administration. Efficacy and safety results were analyzed according to the noninferiority methodological approach.

RESULTS

From the 227 H. pylori positive subjects that were randomized, 194 were finally analyzed as per-protocol. The group 2 eradication rate was 63% and was noninferior to the group 1 eradication rate of 58.5% (upper limit 95% CI: 0.11608; below the noninferiority margin: 0.1200). FISH clarithromycin-resistance was found in 28.2% of the cases. Adverse events, all minor and self-limited, were significantly higher in group 1 than in group 2 (86 vs. 65.4%; p=0.001).

CONCLUSIONS

First-line H. pylori eradication with pantoprazole/levofloxacin/azithromycin combination therapy is as effective as the standard triple therapy, with better tolerability and easier dosing. Clarithromycin resistance should be considered when selecting antibiotics in Helicobacter pylori eradication treatments. ClinicalTrials.gov identifier NCT02726269.

World trends for H. pylori eradication therapy and gastric cancer prevention strategy by H. pylori test-and-treat

Helicobacter pylori-associated gastritis leads to the development of gastric cancer. Kyoto global consensus report on H. pylori gastritis recommended H. pylori eradication therapy to prevent gastric cancer. To manage H. pylori infection, it is important to choose the appropriate regimen considering regional differences in resistance to clarithromycin and metronidazole. Quinolones and rifabutin-containing regimens are useful as third- and fourth-line rescue therapies.

Seven-day genotypic resistance-guided triple Helicobacter pylori eradication therapy can be highly effective

BACKGROUND

The efficacy and applicability of molecular testing to guide the selection of antibiotics in triple Helicobacter pylori (H. pylori) eradication regimens have not been reported. We tested a 7-day, genotypic resistance-guided triple H. pylori eradication therapy in a high-resistance setting.

METHODS

Consecutive dyspeptic patients with H. pylori infection were prospectively enrolled. Genotypic resistances to clarithromycin (23SrRNA mutations) and fluoroquinolones (gyrA mutations) were determined from gastric biopsy specimens using a commercially available molecular assay (GenoTypeâ HelicoDR). A tailored genotypic resistance-guided 7-day triple therapy comprised esomeprazole, amoxicillin, and either clarithromycin (wild-type 23SrRNA), levofloxacin (23SrRNA mutated/wild-type gyrA) or rifabutin (both 23SrRNA/gyrA mutated). H. pylori eradication was confirmed by 13C-urea breath test.

RESULTS

Of 148 subjects screened, 51 patients were enrolled (male/female: 27/24, mean age: 50.7±11.4 years, treatment-naïve/-experienced: 32/19). The molecular kit was easily implemented, allowing for rapid (within 24 h) and relatively inexpensive determination of H. pylori resistance (clarithromycin: 47.1%, fluoroquinolones: 15.7%, dual clarithromycin/fluoroquinolones: 7.8%). For patients who received clarithromycin-, levofloxacin- and rifabutin-containing triple therapy, the respective eradication rates were 24/27, 20/20, and 2/4 by intention-to-treat (ITT); and 24/24, 19/19 and 2/3 by per-protocol (PP) analysis. Overall eradication rates were 90.2% (95% confidence interval [CI] 77.8-96.3%) by ITT and 97.8% (95%CI 87-99.8%) by PP analysis, showing no significant difference between treatment-naïve and -experienced patients (ITT: 87.5% vs. 94.7%, P=0.64; PP: 96.4% vs. 100%, respectively, P=1.00).

CONCLUSIONS

Regardless of prior treatment history, a genotypic resistance-guided 7-day triple therapy, based on a simple molecular assay, achieved a high H. pylori eradication rate.

Consensus on the clinical management, screening-to-treat, and surveillance of Helicobacter pylori infection to improve gastric cancer control on a nationwide scale

BACKGROUND

Previous international consensus statements provided general policies for the management of Helicobacter pylori infection. However, there are geographic differences in the prevalence and antimicrobial resistance of H. pylori, and in the availability of medications and endoscopy. Thus, nationwide or regional consensus statements are needed to improve control of H. pylori infection and gastric cancer.

MATERIALS AND METHODS

This consensus statement for management of H. pylori in Taiwan has three major sections: (1) optimal diagnosis and indications; (2) current treatment strategies; and (3) screening-to-treat and surveillance for control of gastric cancer. The literature review emphasized recent data for development of draft statements and determination of levels of evidence. Twenty-five Taiwan experts conducted a consensus conference, by a modified Delphi process, to modify the draft statements. Consensus, defined as an agreement of least 80% of the experts, and recommendation grade were determined by anonymous voting.

RESULTS

There were 24 consensus statements. Section 1 has seven statements on recommendations for the diagnosis and indications for treatment of H. pylori infection. Section 2 has 10 statements that provide an updated treatment algorithm for first-line, second-line, and third-line regimens. Section 3 has seven statements regarding H. pylori eradication for reducing the risk of gastric cancer, with a cost-benefit analysis. After H. pylori eradication, the consensus highlights the use of endoscopic surveillance and/or chemoprevention to further reduce the burden of gastric cancer.

CONCLUSIONS

This consensus statement has updated recommendations for improving the clinical management of H. pylori infection in areas such as Taiwan, which have high prevalence of H. pylori infection and gastric cancer.

A Novel Stool PCR Test for Helicobacter pylori May Predict Clarithromycin Resistance and Eradication of Infection at a High Rate

Clarithromycin-based regimens are commonly used as a first-line therapy for Helicobacter pylori-positive patients; however, resistance to clarithromycin has led to treatment failures. The aim of this study was to evaluate the feasibility of using stool samples to detect the presence of H. pylori DNA while concurrently detecting mutations associated with resistance to clarithromycin. For this purpose, total DNA was extracted from 294 raw stool specimens from H. pylori-positive and -negative patients. TaqMan real-time PCR amplification was used to detect the presence of H. pylori as well as to predict the phenotype of the organism and the related outcome for patients treated with clarithromycin. Clarithromycin resistance was determined upon analysis of the PCR result. Patients were also tested by a urea breath test and were subjected to esophagogastroduodenoscopy, followed by histology, culture, and a rapid urease test, in order to obtain a consensus patient infection status. Of 294 total stool samples, 227 were deemed true positive. The sensitivity of H. pylori detection by PCR was 93.8%. Of 213 true-positive samples that were sequenced, 36.2% showed point mutations associated with clarithromycin resistance (A2142C, A2142G, A2143G). The final correlation of the mutant genotypes as determined by sequencing with the eradication of infection was 86%. We found that Helicobacter pylori DNA can be detected in human stool specimens with high sensitivity and can therefore be used to determine the presence of the bacterium without obtaining a biopsy sample. Moreover, genotypic resistance to clarithromycin can be predicted without obtaining a biopsy sample, facilitating the choice of the right therapeutic approach.

Noninvasive molecular analysis of Helicobacter pylori: Is it time for tailored first-line therapy?

The main problem of Helicobacter pylori (H. pylori) infection management is linked to antibiotic resistances. This phenomenon has grown in the last decade, inducing a dramatic decline in conventional regimen effectiveness. The causes of resistance are point mutations in bacterial DNA, which interfere with antibiotic mechanism of action, especially clarithromycin and levofloxacin. Therefore, international guidelines have recently discouraged their use in areas with a relevant resistance percentage, suggesting first-line schedules with expected high eradication rates, i.e., bismuth containing or non-bismuth quadruple therapies. These regimens require the daily assumption of a large number of tablets. Consequently, a complete adherence is expected only in subjects who may be motivated by the presence of major disorders. However, an incomplete adherence to antibiotic therapies may lead to resistance onset, since sub-inhibitory concentrations could stimulate the selection of resistant mutants. Of note, a recent meta-analysis suggests that susceptibility tests may be more useful for the choice of first than second-line or rescue treatment. Additionally, susceptibility guided therapy has been demonstrated to be highly effective and superior to empiric treatments by both meta-analyses and recent clinical studies. Conventional susceptibility test is represented by culture and antibiogram. However, the method is not available everywhere mainly for methodology-related factors and fails to detect hetero-resistances. Polymerase chain reaction (PCR)-based, culture-free techniques on gastric biopsy samples are accurate in finding even minimal traces of genotypic resistant strains and hetero-resistant status by the identification of specific point mutations. The need for an invasive endoscopic procedure has been the most important limit to their spread. A further step has, moreover, been the detection of point mutations in bacterial DNA fecal samples. Few studies on clarithromycin susceptibility have shown an overall high sensitivity and specificity when compared with culture or PCR on gastric biopsies. On these bases, two commercial tests are now available although they have shown some controversial findings. A novel PCR method showed a full concordance between tissue and stool results in a preliminary experience. In conclusion, despite poor validation, there is increasing evidence of a potential availability of noninvasive investigations able to detect H. pylori resistances to antibiotics. These kinds of analysis are currently at a very early phase of development and caution should be paid about their clinical application. Only further studies aimed to evaluate their sensitivity and specificity will afford novel data for solid considerations. Nevertheless, noninvasive molecular tests may improve patient compliance, time/cost of infection management and therapeutic outcome. Moreover, the potential risk of a future increase of resistance to quadruple regimens as a consequence of their use on large scale and incomplete patient adherence could be avoided.

Antibiotic resistance and gyrA mutation affect the efficacy of 10-day sitafloxacin-metronidazole-esomeprazole therapy for Helicobacter pylori in penicillin allergic patients

BACKGROUND AND AIM

Helicobacter pylori (H. pylori) eradication regimen has not been standardized for patients with penicillin allergy. We investigated the association between the efficacy of a 10-day sitafloxacin, metronidazole, and esomeprazole triple regimen and antibiotic resistance, in patients with penicillin allergy.

METHODS

Penicillin-allergic patients infected with H. pylori were enrolled between March 2014 and November 2015. The minimum inhibitory concentrations (MICs) of sitafloxacin and metronidazole, and the gyrA mutation status of the H. pylori strains were determined before treatment. The cut-off points for antimicrobial resistance were defined as 8.0 µg/ml for metronidazole and 0.12 µg/ml for sitafloxacin. The patients received the triple therapy (20 mg esomeprazole, bid; 250 mg metronidazole, bid; and 100 mg sitafloxacin, bid) for 10 days. Successful eradication was evaluated using the [¹³C] urea breath test or the H. pylori stool antigen test.

RESULTS

Fifty-seven patients were analyzed, and the overall eradication rate was 89.5%. The eradication rate in cases of double antibiotic resistance to metronidazole and sitafloxacin was 40.0%, whereas for other combinations of resistance, this was above 90.0%. Finally, the eradication rate of gyrA mutation-negative strains was 96.2%, whereas for gyrA mutation-positive strains, it was 83.9%. Adverse events were reported in 31.6% of cases, all of which were mild and tolerable.

CONCLUSION

Ten days of sitafloxacin and metronidazole triple therapy was safe and highly effective in eradicating H. pylori in penicillin-allergic patients. Double resistance to metronidazole and sitafloxacin was an important predicting factor for eradication failure. However, 10 days of the sitafloxacin and metronidazole triple therapy was highly effective if the strain was susceptible to either sitafloxacin or metronidazole.

Treatment of Helicobacter pylori infection: Where are we now?

Gastric cancer and Helicobacter pylori infection remain a burden in many Asian countries. In the face of rising antibiotic resistance, the eradication rate of standard triple therapy is declining in many Asian countries. We reviewed the updated epidemiology of gastric cancer, prevalence of H. pylori infection, and antibiotic resistance in Asia. We also reviewed the strategies to improve the efficacy of H. pylori eradication therapies, including the use of high dose proton pump inhibitor, four drug therapies (including bismuth quadruple, concomitant, and sequential therapy), susceptibility guided therapy, extending the treatment duration to 14 days, and development of effective rescue therapy. Four drug therapies are usually more effective than triple therapy when given in the same duration, except in areas with concomitantly high metronidazole resistance and low clarithromycin resistance. The efficacies of different four drug regimens appeared to be similar. However, trials from different geographic areas showed contradictory results, indicating that the optimal therapy should be decided according to the local prevalence of antibiotic resistance. We proposed a prediction model to calculate the efficacy of different regimens according to the prevalence of antibiotic resistance. More large randomized trials which provide information on the antibiotic resistance are urgently needed to build a more accurate and reliable model. It is hoped that we will be able to decide the optimal regimens by routine surveillance of antibiotic resistance.

Concomitant, bismuth quadruple, and 14-day triple therapy in the first-line treatment of Helicobacter pylori: a multicentre, open-label, randomised trial

BACKGROUND

Whether concomitant therapy is superior to bismuth quadruple therapy or 14-day triple therapy for the first-line treatment of Helicobacter pylori infection remains poorly understood. We aimed to compare the efficacy and safety of 10-day concomitant therapy, 10-day bismuth quadruple therapy, and 14-day triple therapy in the first-line treatment of H pylori.

METHODS

In this multicentre, open-label, randomised trial, we recruited adult patients (aged >20 years) with H pylori infection from nine medical centres in Taiwan. Patients who had at least two positive tests from the rapid urease test, histology, culture, or serology or who had a single positive ¹³C-urea breath test for gastric cancer screening were eligible for enrolment. Patients were randomly assigned (1:1:1) to either concomitant therapy (lansoprazole 30 mg, amoxicillin 1 g, clarithromycin 500 mg, and metronidazole 500 mg, all given twice daily) for 10 days; bismuth quadruple therapy (bismuth tripotassium dicitrate 300 mg four times a day, lansoprazole 30 mg twice daily, tetracycline 500 mg four times a day, and metronidazole 500 mg three times a day) for 10 days; or triple therapy (lansoprazole 30 mg, amoxicillin 1 g, and clarithromycin 500 mg, all given twice daily) for 14 days. A computer-generated permuted block randomisation sequence with a block size of 6 was used for randomisation, and the sequence was concealed in an opaque envelope until the intervention was assigned. Investigators were masked to treatment allocation. The primary outcome was the eradication frequency of H pylori with first-line therapy assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01906879.

FINDINGS

Between July 17, 2013, and April 20, 2016, 5454 patients were screened for eligibility. Of these, 1620 patients were randomly assigned in this study. The eradication frequencies were 90·4% (488/540 [95% CI 87·6-92·6]) for 10-day bismuth quadruple therapy, 85·9% (464/540 [82·7-88·6]) for 10-day concomitant therapy, and 83·7% (452/540 [80·4-86·6]) for 14-day triple therapy in the intention-to-treat analysis. 10-day bismuth quadruple therapy was superior to 14-day triple therapy (difference 6·7% [95% CI 2·7-10·7, p=0·001), but not 10-day concomitant therapy. 10-day concomitant therapy was not superior to 14-day triple therapy. The frequency of adverse events was 67% (358/533) in patients treated with 10-day bismuth quadruple therapy, 58% (309/535) in patients treated with 10-day concomitant therapy, and 47% (252/535) in patients treated with 14-day triple therapy.

INTERPRETATION

Bismuth quadruple therapy is preferable to 14-day triple therapy in the first-line treatment in the face of rising prevalence of clarithromycin resistance. Concomitant therapy given for 10 days might not be optimum and a longer treatment length should be considered.

FUNDING

National Taiwan University Hospital and Ministry of Science and Technology of Taiwan.

Sequential therapy for 10 days versus triple therapy for 14 days in the eradication of Helicobacter pylori in the community and hospital populations: a randomised trial

OBJECTIVE

Significant heterogeneity was observed in previous trials that assessed the efficacies of sequential therapy for 10 days (S10) versus triple therapy for 14 days (T14) in the first-line treatment of Helicobacter pylori. We aimed to compare the efficacy of S10 and T14 and assess the factors affecting their efficacies.

DESIGN

We conducted this open-label randomised multicentre trial in eight hospitals and one community in Taiwan. 1300 adult subjects with H pylori infection naïve to treatment were randomised (1:1) to receive S10 (lansoprazole and amoxicillin for the first 5 days, followed by lansoprazole, clarithromycin and metronidazole for another 5 days) or T14 (lansoprazole, amoxicillin and clarithromycin for 14 days). All drugs were given twice daily. Successful eradication was defined as negative ¹³C-urea breath test at least 6 weeks after treatment. Our primary outcome was the eradication rate by intention-to-treat (ITT) and per-protocol (PP) analyses. Antibiotic resistance was determined by agar dilution test.

RESULTS

The eradication rates of S10 and T14 were 87.2% (567/650, 95% CI 84.4% to 89.6%) and 85.7% (557/650, 95% CI 82.8% to 88.2%) in the ITT analysis, respectively, and were 91.6% (556/607, 95% CI 89.1% to 93.4%) and 91.0% (548/602, 95% CI 88.5% to 93.1%) in the PP analysis, respectively. There were no differences in compliance or adverse effects. The eradication rates in strains susceptible and resistant to clarithromycin were 90.7% and 62.2%, respectively, for S10, and were 91.5% and 44.4%, respectively, for T14. The efficacy of T14, but not S10, was affected by CYP2C19 polymorphism.

CONCLUSIONS

S10 was not superior to T14 in areas with low clarithromycin resistance.

TRIAL REGISTRATION NUMBER

NCT01607918.

Systematic review with meta-analysis: the efficacy of levofloxacin triple therapy as the first- or second-line treatments of Helicobacter pylori infection

BACKGROUND

Levofloxacin triple therapy has been used for the first-line and second-line treatment of Helicobacter pylori infection for more than 10 years.

AIMS

To systematically review the efficacy of levofloxacin triple therapy in the first- and second-line treatment, and to assess the time trend and factors that might affect its efficacy.

METHODS

Prospective trials reporting the efficacy of levofloxacin triple therapy in either the first-line or second-line treatment of H. pylori infection in adults were searched from the PubMed and Cochrane database from January 2000 to September 2015. Meta-analysis was performed to calculate the cumulative eradication rate and the efficacies in subgroups.

RESULTS

Of the 322 articles identified, a total of 4574 patients from 41 trials, including 16 trials in the first-line treatment and 25 trials in the second-line treatment were eligible for analysis. The cumulative eradication rate was 77.3% (95% confidence intervals, CI: 74.7-79.6) and was 80.7% (95% CI 77.1-83.7) in the first-line treatment and 74.5% (95% CI: 70.9-77.8) in the second-line treatment. The efficacies of levofloxacin triple therapy before 2008, between 2009 and 2011, and after 2012 were 77.4%, 79.6% and 74.8% respectively. The eradication rate was higher when levofloxacin was given once daily (80.6%, 95% CI: 77.1-83.7) than twice daily (73.6%, 95% CI: 69.7-77.2). The efficacy was significantly higher in levofloxacin-susceptible strains than resistant strains (81.1% vs. 36.3%, risk ratio 2.18, 95% CI: 1.6-3, P < 0.001).

CONCLUSION

The efficacy of levofloxacin triple therapy has been lower than 80% in many countries and it is not recommended when the levofloxacin resistance is higher than 5-10%.

Efficacy of 10-day Sitafloxacin-Containing Third-Line Rescue Therapies for Helicobacter pylori Strains Containing the gyrA Mutation

BACKGROUND AND AIM

Sitafloxacin-containing Helicobacter pylori eradication therapy is a promising third-line therapeutic approach, but there is no previous studies between gyrA mutation status of H. pylori strains and the efficacy of 10-day sitafloxacin-containing regimens. Here, we assessed the efficacy of 2 different 10-day sitafloxacin-containing rescue regimens.

METHODS

Patients who failed first- and second-line eradication therapies were enrolled. The minimum inhibitory concentrations (MICs) of sitafloxacin, amoxicillin, and metronidazole and the gyrA mutation status of the H. pylori strains were determined before treatment. The patients were randomized to receive a 10-day triple therapy containing either esomeprazole (20 mg, b.i.d.), amoxicillin (500 mg, q.i.d.), and sitafloxacin (100 mg, b.i.d.) (EAS regimen) or esomeprazole (20 mg, b.i.d.), metronidazole (250 mg, b.i.d.), and sitafloxacin (100 mg, b.i.d.) (EMS regimen). Eradication rates were evaluated by the [13C] urea breath test or the H. pylori stool antigen test.

RESULTS

All patients with gyrA mutation-negative strains (24 in EAS and 16 in EMS) showed successful eradication, irrespective of the regimen they received. In patients with gyrA mutation-positive strains, we found eradication rates of 70.3% (26/37) and 66.7% (26/39) in the EAS and EMS groups in per-protocol population, respectively (p = .81). According to logistic regression analyses, the MICs of sitafloxacin, which were strongly associated with gyrA mutation status, were independently associated with successful eradication in both groups. This study was registered in the UMIN Clinical Trials Registry as UMIN000006483.

CONCLUSION

There is no significant difference in the eradication rates between EAS and EMS, regardless of the gyrA mutation status of the H. pylori strains. GyrA mutation status was an important factor in predicting successful eradication with sitafloxacin-containing rescue therapies.

Surveillance of Levofloxacin Resistance in Helicobacter pylori Isolates in Bogotá-Colombia (2009-2014)

Increased resistance of Helicobacter pylori to clarithromycin and metronidazole has resulted in recommendation to substitute fluoroquinolones for eradication therapy. The aims of the study were to determine the prevalence and changes in primary levofloxacin resistance related to H. pylori gyrA sequences. The study utilized H. pylori strains isolated from patients undergoing gastroscopy in Bogotá, Colombia from 2009 to 2014. Levofloxacin susceptibility was assessed by agar dilution. Mutations in gyrA sequences affecting the quinolone resistance-determining region (QRDR) were evaluated by direct sequencing. Overall, the mean prevalence of primary levofloxacin resistance was 18.2% (80 of 439 samples). Resistance increased from 11.8% (12/102) in 2009 to 27.3% (21/77) in 2014 (p = 0.001). gyrA mutations in levofloxacin resistant strains were present in QRDR positions 87 and 91. The most common mutation was N87I (43.8%, 35/80) followed by D91N (28.8%, 23/80) and N87K (11.3%, 9/80). Levofloxacin resistance increased markedly in Colombia during the six-year study period. Primary levofloxacin resistance was most often mediated by point mutations in gyrA, with N87I being the most common QRDR mutation related to levofloxacin resistance.

Levofloxacin Sequential Therapy vs Levofloxacin Triple Therapy in the Second-Line Treatment of Helicobacter pylori: A Randomized Trial

OBJECTIVES

The efficacy of levofloxacin triple therapy has fallen below 80% in the second-line treatment of Helicobacter pylori (H. pylori). We aimed to assess whether the levofloxacin sequential therapy is more effective than levofloxacin triple therapy in the second-line treatment.

METHODS

This open-label, randomized, multicenter trial was conducted between 2012 and 2015. H. pylori-infected subjects who failed from clarithromycin-based regimens (N=600) were randomized (1:1) to receive levofloxacin sequential therapy (LS: lansoprazole and amoxicillin for the first 5 days, followed by lansoprazole, levofloxacin, and metronidazole for another 5 days) or levofloxacin triple therapy (LT: lansoprazole, amoxicillin, and levofloxacin for 10 days). Successful eradication was defined as negative (13)C-urea breath test at least 6 weeks after treatment. Our primary outcome was the eradication rate by intention-to-treat (ITT) and per-protocol (PP) analyses. Antibiotic resistance was determined by agar dilution test.

RESULTS

The prevalence of clarithromycin, levofloxacin, and metronidazole resistance was 60, 17.6, and 36.9%, respectively. The eradication rates of LS and LT were 84.3% (253/300) and 75.3% (226/300), respectively, in the ITT analysis (P=0.006) and 86.3% (253/293) and 78.8% (223/283), respectively, in the PP analysis (P=0.021). The efficacies of both LS and LT were affected by levofloxacin resistance. The secondary resistance of levofloxacin was 66.7 and 73.9% after LS and LT, respectively. The efficacies of LS and LT were not affected by the CYP2C19 polymorphism.

CONCLUSIONS

Levofloxacin sequential therapy was more effective than levofloxacin triple therapy, and it is recommended in the second-line treatment for H. pylori (

TRIAL REGISTRATION NUMBER

NCT01537055).

Systematic review with meta-analysis: 10- or 14-day sequential therapy vs. 14-day triple therapy in the first line treatment of Helicobacter pylori infection

BACKGROUND

Whether 10-day or 14-day sequential therapy is superior to 14-day triple therapy in the first-line treatment of Helicobacter pylori remains controversial.

AIM

To compare the efficacy of 10-day or 14-day sequential therapy vs. 14-day triple therapy.

METHODS

Randomised controlled trials (RCTs) comparing 10-day or 14-day sequential therapy and 14-day triple therapy as first-line treatment in adults were searched from the PubMed and Cochrane databases from 2000 to October 2015. Abstracts from international annual conferences were also searched. The primary and secondary outcomes were the eradication rate according to the intention-to-treat analysis and adverse effects, respectively.

RESULTS

Of the 109 articles identified, 13 RCTs including 2749 patients in the sequential therapy group and 2424 patients in the 14-day triple therapy group were eligible. Overall, sequential therapy for 10 or 14 days was not significantly superior to 14-day triple therapy [Risk ratio (RR) 1.04, 95% confidence interval (CI) 0.99-1.08, P = 0.145]. However, there was significant heterogeneity (I(2) = 57.6%, P = 0.005). In the subgroup analysis of four trials, we found that 14-day sequential therapy was significantly more effective than 14-day triple therapy (RR: 1.09, 95% CI: 1.04-1.16, P = 0.002), and there was no significant heterogeneity (I(2) = 0%, P = 0.624) in this comparison. Sequential therapy given for 10 days was not superior to 14-day triple therapy (RR: 1.03, 95% CI: 0.98-1.09, P = 0.207). There was no significant difference in the risk of adverse effects.

CONCLUSION

Sequential therapy given for 14 days, but not 10 days, was more effective than 14-day triple therapy as first-line treatment.

Molecular Approaches to Identify Helicobacter pylori Antimicrobial Resistance

Antimicrobial susceptibility testing is needed to adapt Helicobacter pylori treatment to obtain the best results. Beside the standard phenotypic methods, molecular methods are increasingly used. The value of these molecular tests is that they are quick, independent of the transport conditions, easy to standardize, and commercial kits are available. In this article, these methods are reviewed, focusing on the determination of H pylori resistance to macrolides and fluoroquinolones, and mentioning also the methods used for tetracycline and rifampin.

High Helicobacter pylori cure rate with sitafloxacin-based triple therapy

BACKGROUND

Bacterial resistance of Helicobacter pylori to antibiotics is increasing and it often leads to failure of antibiotic treatment. A new sitafloxacin-based triple therapy was developed to counter this situation; the fluoroquinolone sitafloxacin has a low minimum inhibitory concentration for H. pylori.

AIM

To investigate the efficacy in Japanese patients of sitafloxacin-based triple therapy and document its efficacy in relation to anti-microbial susceptibility.

METHODS

We investigated the efficacy of a 1-week sitafloxicin-based regimen of rabeprazole 10 mg four times daily (q.d.s.), metronidazole 250 mg twice daily (b.d.) and sitafloxacin 100 mg b.d. in 180 H. pylori-positive Japanese patients (first-line treatment: n = 45, second-line; n = 41, third-line: n = 94). At 8 weeks, patients were given the (13) C-urea breath test to assess eradication status.

RESULTS

Eradication rate was 92.2% [95% confidence interval (CI): 87.3-95.7%, 166/180] in intention-to-treat analysis. Although the eradication rate was higher in patients treated with first-line therapy [45/45 (100%, 95% CI: 83.4-100%)] than in those with second- [38/41 (92.7%, 80.1-98.5%)] or third-line therapy [83/94 (88.3%, 80.0-94.0%)], no significant differences were noted with respect to the number of previous therapy attempts (P = 0.054). Eradication rates in patients infected with sensitive- and resistant strains to metronidazole were 96.6% (28/29) and 96.3% (77/80) (P = 0.941), respectively, while rates were 98.4% (60/61) in sitafloxacin-sensitive and 50.0% (1/2) in sitafloxacin resistant strains (P < 0.001).

CONCLUSION

Sitofloxacin-based triple therapy with metronidazole b.d. and rabeprazole q.d.s. achieved an eradication rate exceeding 88%, irrespective of eradication history, CYP2C19 genotype, or metronidazole resistance status.

Efficacy of real-time PCR-based detection of Helicobacter pylori infection and genotypic resistance-guided quadruple therapy as the first-line treatment for functional dyspepsia with Helicobacter pylori infection

BACKGROUND

The eradication rate of Helicobacter pylori is steadily decreasing because of increasing resistance to clarithromycin. According to the new version of Maastricht IV guidelines, molecular tests can be performed as a substitute for bacterial culture and the standard clarithromycin susceptibility test for the detection of H. pylori and clarithromycin resistance directly on gastric biopsy samples.

OBJECTIVE

To evaluate the clinical efficacy of H. pylori detection using a molecular test and treatment outcomes of the clarithromycin-based genotypic resistance test.

MATERIALS AND METHODS

A total of 385 patients diagnosed with functional dyspepsia were recruited in this clinical trial. Total DNA was extracted from formalin-fixed paraffin-embedded samples and prepared for a molecular test and H. pylori detection was performed simultaneously by modified Giemsa staining. Genotypically sensitive patients with positive H. pylori were treated by quadruple therapy: bismuth potassium citrate, rabeprazole, amoxicillin, and clarithromycin (BRAC) and genotypically resistant individuals were treated by bismuth potassium citrate, rabeprazole, amoxicillin, and furazolidone (BRAF) twice daily for 7 consecutive days. The eradication rate of H. pylori was assessed using the C-urea breath test at 6 weeks after treatment.

RESULTS

The prevalence of H. pylori infection in functional dyspepsia patients was 35.3% (136/385), 29.1% for women (53/182) and 40.9% for men (83/203). The sensitivities of real-time PCR and histological examinations were 95.6% (130/136) and 69.9% (95/136). Forty-one samples were found to be positive by real-time PCR alone and six by histological examination alone, the majority of which (32/41, 5/6) were identified as grade 1 multiplicity of infection. The overall resistance rate to clarithromycin was 37.7% (49/130): 37.3% (19/51) for women and 38.0% for men (30/79). Eighty-nine patients with positive H. pylori detected by both real-time PCR and histological examinations received quadruple therapies. For the intention-to-treat analysis, the eradication rates of BRAC and BRAF were 98% (52/53) and 92% (33/36), or 100% (52/52) and 94% (33/35) for per-protocol analysis.

CONCLUSION

Real-time PCR is efficacious for H. pylori detection and genotypic resistance-guided quadruple therapy has a high efficacy in treating functional dyspepsia with H. pylori infection.

Quinolone-containing therapies in the eradication of Helicobacter pylori

Fluoroquinolones, especially levofloxacin, are used in the eradication of Helicobacter pylori worldwide. Many consensus guidelines recommend that the second-line rescue therapy for H. pylori eradication consists of a proton pump inhibitor, a quinolone, and amoxicillin as an option. Unfortunately, quinolone is well associated with a risk of developing bacterial resistance. In this paper, we review quinolone-containing H. pylori eradication regimens and the challenges that influence the efficacy of eradication. It is generally suggested that the use of levofloxacin should be confined to “rescue” therapy only, in order to avoid a further rapid increase in the resistance of H. pylori to quinolone. The impact of quinolone-containing H. pylori eradication regimens on public health issues such as tuberculosis treatment must always be taken into account. Exposure to quinolone is relevant to delays in diagnosing tuberculosis and the development of drug resistance. Extending the duration of treatment to 14 days improves eradication rates by >90%. Tailored therapy to detect fluoroquinolone-resistant strains can be done by culture-based and molecular methods to provide better eradication rates. Molecular methods are achieved by using a real-time polymerase chain reaction to detect the presence of a gyrA mutation, which is predictive of treatment failure with quinolones-containing triple therapy.

The clinical and bacteriological factors for optimal levofloxacin-containing triple therapy in second-line Helicobacter pylori eradication

Quinolone has the disadvantage of easily acquired drug resistance. It is important to prescribe it wisely for a high eradication rate. The current study aimed to determine the clinical and bacteriological factors for optimal levofloxacin-containing triple therapies in second-line H. pylori eradication. We enrolled a total of 158 H. pylori-infected patients who failed H. pylori eradication using the 7-day standard triple therapy (proton-pump inhibitor [PPI] twice daily, 500 mg clarithromycin twice daily, and 1 g amoxicillin twice daily). They were prescribed with either a 10-day (group A) or 14-day (group B) levofloxacin-containing triple therapy group (levofloxacin 500 mg once daily, amoxicillin 1 g twice daily, and esomeprazole 40 mg twice daily for 10 days) by their clinicians. Follow-up studies to assess treatment responses were carried out 8 weeks later. The eradication rates attained by groups A and B were 73.6% (95% confidence interval [CI] = 63.9–85.3%) and 90.5% (95% CI = 84.5–98.1%), respectively in the per protocol analysis (P = 0.008 in the per protocol analysis) and 67.1% (95% CI = 56.6–78.5%) and 84.8% (95% CI = 76.8–93.4%), respectively, in the intention-to-treat analysis (P = 0.009). The subgroup analysis revealed that H. pylori eradication rates for group A patients with levofloxacin-susceptible strains were 92.9% (13/14) but it dropped to 12.5% (1/8) when levofloxacin-resistant strains existed. H. pylori was eradicated among all the group B patients with levofloxacin-susceptible strains, but only half of patients with levofloxacin-resistant strains were successfully eradicated. In conclusion, this study confirms the effectiveness of 14-day treatment. Importantly, the results imply that 10-day treatment duration should be optimal if a culture can be performed to confirm the existence of susceptible strains. The duration of H. pylori eradication and levofloxacin resistance were the influencing factors for successful treatment. This study suggests that tailored levofloxacin-containing therapy should be administered only for patients with susceptible strains because it can achieve >90% success rates.

Detection of genotypic clarithromycin-resistant Helicobacter pylori by string tests

AIM

To evaluate the utility of the string test to detect genotypic clarithromycin-resistant Helicobacter pylori (H. pylori) by polymerase chain reaction (PCR)-restriction fragment length polymorphism.

METHODS

Patients undergoing endoscopic examinations were enrolled in the present study. String tests were done on the next day of endoscopy. Segments of 23S rRNA were amplified from DNA obtained from string tests. PCR-restriction fragment length polymorphism was accomplished by restriction enzymes BbsI and BsaI recognizing the mutation site A to G at 2143 or at 2142 of 23S rRNA domain V, respectively.

RESULTS

One hundred and thirty-four patients with H. pylori infection underwent string tests. To compare phenotypic resistance, 43 isolates were successfully cultured in 79 patients in whom 23S rRNA was successfully amplified. Of five patients with clarithromycin-resistant H. pylori, 23S rRNA of H. pylori isolates from four patients could be digested by BsaI. In 38 susceptible isolates, 23S rRNA of H. pylori isolates from 36 patients could not be digested by either BsaI or BbsI. The sensitivity and specificity of the string test to detect genotypic clarithromycin resistance were 66.7% and 97.3%, respectively. Positive and negative predictive values were 80% and 94.7%, respectively.

CONCLUSION

String test with molecular analysis is a less invasive method to detect genotypic resistance before treatment. Further large-scale investigations are necessary to confirm our results.

Sequential versus triple therapy for the first-line treatment of Helicobacter pylori: a multicentre, open-label, randomised trial

BACKGROUND

Whether sequential treatment can replace triple therapy as the standard treatment for Helicobacter pylori infection is unknown. We compared the efficacy of sequential treatment for 10 days and 14 days with triple therapy for 14 days in first-line treatment.

METHODS

For this multicentre, open-label, randomised trial, we recruited patients (≥20 years of age) with H pylori infection from six centres in Taiwan. Using a computer-generated randomisation sequence, we randomly allocated patients (1:1:1; block sizes of six) to either sequential treatment (lansoprazole 30 mg and amoxicillin 1 g for the first 7 days, followed by lansoprazole 30 mg, clarithromycin 500 mg, and metronidazole 500 mg for another 7 days; with all drugs given twice daily) for either 10 days (S-10) or 14 days (S-14), of 14 days of triple therapy (T-14; lansoprazole 30 mg, amoxicillin 1 g, and clarithromycin 500 mg for 14 days; with all drugs given twice daily). Investigators were masked to treatment allocation. Our primary outcome was the eradication rate in first-line treatment by intention-to-treat (ITT) and per-protocol (PP) analyses. This trial is registered with ClinicalTrials.gov, number NCT01042184.

FINDINGS

Between Dec 28, 2009, and Sept 24, 2011, we enrolled 900 patients: 300 to each group. The eradication rate was 90·7% (95% CI 87·4-94·0; 272 of 300 patients) in the S-14 group, 87·0% (83·2-90·8; 261 of 300 patients) in the S-10 group, and 82·3% (78·0-86·6; 247 of 300 patients) in the T-14 group. Treatment efficacy was better in the S-14 group than it was in the T-14 group in both the ITT analysis (number needed to treat of 12·0 [95% CI 7·2-34·5]; p=0·003) and PP analyses (13·7 [8·3-40], p=0·003). We recorded no significant difference in the occurrence of adverse effects or in compliance between the three groups.

INTERPRETATION

Our findings lend support to the use of sequential treatment as the standard first-line treatment for H pylori infection.

FUNDING

National Taiwan University Hospital and National Science Council.

Efficacy of genotypic resistance-guided sequential therapy in the third-line treatment of refractory Helicobacter pylori infection: a multicentre clinical trial

OBJECTIVES

The efficacy of sequential therapy and the applicability of genotypic resistance to guide the selection of antibiotics in the third-line treatment of Helicobacter pylori have not been reported. We aimed to assess the efficacy of genotypic resistance-guided sequential therapy in third-line treatment.

METHODS

Genotypic and phenotypic resistances were determined in patients who failed at least two eradication therapies by PCR with direct sequencing and agar dilution test, respectively. The patients were retreated with sequential therapy containing esomeprazole and amoxicillin for the first 7 days, followed by esomeprazole and metronidazole plus clarithromycin, levofloxacin or tetracycline for another 7 days (all twice daily), according to genotypic resistance determined using gastric biopsy specimens. Eradication status was determined by the (13)C-urea breath test. Trial registered at clinicaltrials.gov (identifier: NCT01032655).

RESULTS

The overall eradication rate was 80.7% (109/135, 95% CI 73.3%-86.5%) in the intention-to-treat analysis. The presence of amoxicillin resistance (OR 6.83, 95% CI 1.62-28.86, P = 0.009) and prior sequential therapy (OR 4.77, 95% CI 1.315-17.3, P = 0.017), but not tetracycline resistance (tetracycline group), were associated with treatment failure. The eradication rates in patients who received clarithromycin-, levofloxacin- and tetracycline-based sequential therapies were 78.9% (15/19), 92.2% (47/51) and 71.4% (25/35) in strains susceptible to clarithromycin, levofloxacin and tetracycline, respectively.

CONCLUSIONS

A simple molecular method guiding sequential therapy can achieve a high eradication rate in the third-line treatment of refractory H. pylori infection.

Comparative in vitro antimicrobial susceptibility and synergistic activity of antimicrobial combinations against Helicobacter pylori isolates in Taiwan

BACKGROUND

Antimicrobial resistance is a major determinant of Helicobacter pylori treatment failures. We conducted a population-based survey to monitor changing antimicrobial susceptibility of H. pylori isolates in Taiwan, with a focus on combinatorial effects of synergism and the influence of acidity.

METHODS

H. pylori isolates from endoscopic specimens taken from patients enrolled at two medical centers were obtained between January 2008 and December 2009. Minimum inhibitory concentrations (MICs) were determined by agar dilution and Etest methods. Agar media of varying pH (pH 7.3, 6.0, or 5.0) were used to assess whether acidity influences the bactericidal effects of the agents tested. Time-kill assays were used to assess for synergism between different drug combinations.

RESULTS

A total of 176 non-duplicate H. pylori isolates from endoscopic specimens were tested. The following MIC90 (mg/L) (susceptible) results were obtained at neutral pH 7.3: amoxicillin, 0.25 (100%); tetracycline, 0.5 (100%); metronidazole, 32 (67.6%); clarithromycin, 0.25 (90.3%); ciprofloxacin, 1 (92.0%); gemifloxacin, 0.5 (94.9%); levofloxacin, 1 (93.2%); and moxifloxacin, 1 (91.5%). A decrease in pH from 6.0 to 5.0 significantly decreased the antimicrobial activity of levofloxacin and moxifloxacin against H. pylori. For clarithromycin-susceptible isolates, levofloxacin combined with clarithromycin provided both synergistic and bactericidal effects. For clarithromycin-resistant isolates with amoxicillin hypersusceptibility (MIC <0.01 mg/L), levofloxacin with amoxicillin or minocycline had at best additive effect but no bactericidal effects.

CONCLUSION

Amoxicillin, tetracycline, clarithromycin, and fluoroquinolones, but not metronidazole, showed good in vitro anti-H. pylori activity (>90% susceptible). Synergism was only observed for clarithromycin-susceptible isolates. Acidity adversely influenced the antimicrobial activity of levofloxacin against H. pylori.

Quadruple therapy with moxifloxacin and bismuth for first-line treatment of Helicobacter pylori

AIM: To compare triple therapy vs quadruple therapy for 10 d as first-line treatment of Helicobacter pylori (H. pylori) infection.

METHODS: Consecutive H. pylori positive patients never treated in the past for this infection were randomly treated with triple therapy of pantoprazole (PAN) 20 mg bid, amoxicillin (AMO) 1 g bid and moxifloxacin (MOX) 400 mg bid for 10 d (PAM) or with quadruple therapy of PAN 20 mg bid, AMO 1 g bid, MOX 400 mg bid and bismuth subcitrate 240 mg bid for 10 d (PAMB). All patients were found positive at 13 C-Urea breath test (UBT) performed within ten days prior to the start of the study. A successful outcome was confirmed with an UBT performed 8 wk after the end of treatment. χ² analysis was used for statistical comparison. Per protocol (PP) and intention-to-treat (ITT) values were also calculated.

RESULTS: Fifty-seven patients were enrolled in the PAM group and 50 in the PAMB group. One patient in each group did not return for further assessment. Eradication was higher in the PAMB group (negative: 46 and positive: 3) vs the PAM group (negative: 44 and positive: 12). The H. pylori eradication rate was statistically significantly higher in the PAMB group vs the PAM group, both with the PP and ITT analyses (PP: PAMB 93.8%, PAM 78.5%, P < 0.02; ITT: PAMB 92%, PAM 77.1 %, P <0.03).

CONCLUSION: The addition of bismuth subcitrate can be considered a valuable adjuvant to triple therapy in those areas where H. pylori shows a high resistance to fluoroquinolones.

Gemifloxacin can partially overcome quinolone resistance of H. pylori with gyrA mutation in Taiwan

BACKGROUNDS

The levofloxacin resistance caused by gyrA gene mutation is rising rapidly to limit wide application for Helicobacter pylori eradication. We investigated whether gemifloxacin has a superior antimicrobial activity to levofloxacin against H. pylori.

MATERIALS AND METHODS

 Forty-four consecutive clinical H. pylori isolates with levofloxacin resistance and 80 randomly selected levofloxacin-sensitive controls were tested for gemifloxacin sensitivity by E-test. The resistance to levofloxacin or gemifloxacin was defined as minimal inhibitory concentration (MIC) > 1 mg/L. The clinical features and GyrA mutation patterns checked by direct sequencing were also analyzed to assess its association with the H. pylori gemifloxacin resistance.

RESULTS

 All levofloxacin-sensitive H. pylori isolates were sensitive to gemifloxacin. Eight strains (18.2%) resistant to levofloxacin could be still sensitive to gemifloxacin. Gemifloxacin achieved a 5-time lower in MIC levels against levofloxacin-resistant isolates. Nearly all levofloxacin-resistant isolates (97.7%, 43/44) had GyrA mutation at amino acid position 87 or 91. Double mutation sites may play dual roles in quinolone resistance, as N87K plus H57Y or D91N plus V77A mutations showed high-level resistance to both quinolones; whereas D91Y plus A97V or D91N plus A97V mutations showed low level levofloxacin resistance to become sensitive to gemifloxacin. In H. pylori isolates with single N87K, D91Y or D91N mutation, near 20% was gemifloxacin-sensitive and levofloxacin-resistant. The gemifloxacin-resistant rate of H. pylori was higher in patients with gastric ulcer than in those without (p <.05).

CONCLUSION

 Gemifloxacin is superior to levofloxacin in antimicrobial activity against clinical H. pylori isolates, and even overcome some levofloxacin resistance.