Quinolone-Based Third-Line Therapy for Helicobacter pylori Eradication

Development and validation of next-generation sequencing panel for personalized Helicobacter pylori eradication treatment targeting multiple species

Introduction

The decreasing Helicobacter pylori eradication rate is primarily attributed to antibiotic resistance, and further exacerbated by uniform drug administration disregarding a host's metabolic capability. Consequently, applying personalized treatment based on antibiotic resistance-associated variants and the host's metabolic phenotype can potentially increase the eradication rate.

Method

A custom next-generation sequencing panel for personalized H. pylori eradication treatment (NGS-PHET) was designed which targeted the regions for amoxicillin, clarithromycin, metronidazole, tetracycline, and levofloxacin-resistance in H. pylori and human proton-pump inhibitor (PPI) metabolism. The libraries were constructed following customized methods and sequenced simultaneously. The customized framework criteria, grounded in previously reported antibiotic resistance associated variants and the host's PPI metabolism, was applied to the NGS-PHET results and suggested a personalized treatment for each subject, which was validated through each subject's actual eradication outcome.

Results

Both previously reported and novel variants were identified from H. pylori sequencing results. Concurrently, five CYP2C19 homozygous extensive metabolizers and three CYP3A4 intermediate metabolizers were identified. Among the total of 12 subjects, clarithromycin triple therapy was suggested for five subjects, bismuth quadruple therapy was suggested for six subjects, and rifabutin triple therapy was suggested for one subject by following the customized framework criteria. The treatment suggestion for nine of the 12 subjects was consistent with the treatment that each subject achieved eradication with.

Discussion

Applying the methodology using the NGS-PHET and customized framework helps to perform eradication treatment quickly and effectively in most patients with antibiotic-resistant H. pylori strains, and is also useful in research to find novel antibiotic-resistance candidates.

Rapid diagnosis and precision treatment of Helicobacter pylori infection in clinical settings

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of approximately half of the worldwide population, with higher prevalence in densely populated areas like Asia, the Caribbean, Latin America, and Africa. H. pylori infections range from asymptomatic cases to potentially fatal diseases, including peptic ulcers, chronic gastritis, and stomach adenocarcinoma. The management of these conditions has become more difficult due to the rising prevalence of drug-resistant H. pylori infections, which ultimately lead to gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. In 1994, the International Agency for Research on Cancer (IARC) categorized H. pylori as a Group I carcinogen, contributing to approximately 780,000 cancer cases annually. Antibiotic resistance against drugs used to treat H. pylori infections ranges between 15% and 50% worldwide, with Asian countries having exceptionally high rates. This review systematically examines the impacts of H. pylori infection, the increasing prevalence of antibiotic resistance, and the urgent need for accurate diagnosis and precision treatment. The present status of precision treatment strategies and prospective approaches for eradicating infections caused by antibiotic-resistant H. pylori will also be evaluated.

Newer, Older, and Alternative Agents for the Eradication of Helicobacter pylori Infection: A Narrative Review

Although discovered 40 years ago, Helicobacter pylori infection is still raising diagnostic and therapeutic problems today. The infection is currently managed based on statements in several guidelines, but implementing them in practice is a long process. Increasing antibiotic resistance and weak compliance of the patients limit the efficacy of eradication regimens, leaving much room for improvement. Third-generation proton pump inhibitors have added little to the results of the first two generations. Potassium-competitive acid blockers have a stronger and longer inhibitory action of acid secretion, increasing the intragastric pH. They obtained superior results in eradication when compared to proton pump inhibitors. Instead of innovative antibiotics, derivatives of existing antimicrobials were developed; some new fluoroquinolones and nitazoxanide seem promising in practice, but they are not recommended by the guidelines. Carbonic anhydrase inhibitors have both anti-secretory and bactericidal effects, and some researchers are expecting their revival in the treatment of infection. Capsules containing components of the eradication regimens have obtained excellent results, but are of limited availability. Probiotics, if containing bacteria with anti-Helicobacter pylori activity, may be useful, increasing the rates of eradication and lowering the prevalence and severity of the side effects.

DEVELOPMENT OF APIGENIN LOADED GASTRORETENTIVE MICROSPONGE FOR THE TARGETING OF HELICO BACTER PYLORI

The goal of the present work was to invent an apigenin-stacked gastroretentive microsponge to target H. pylori. The quasi-emulsion technique was used to prepare microsponges, which were then tested for various physicochemical properties, in-vivo gastric retention, and in-vitro anti-H. pylori study. The microsponge that demonstrated a comparatively good product yield (76.23 ± 0.84), excellent entrapment efficiency (97.84 ± 0.85), sustained in-vitro gastric retention period, and prolonged drug release were chosen for further investigations. The microsponge's SEM analysis showed that it had a spherical form, porous surface, and interconnected spaces. No drug-polymer interactions were detected in the FTIR investigation. Apigenin was found to be dispersed in the microsponge's polymeric matrix according to DSC & XRD investigations. Moreover, the microsponge in the rat's stomach floated for 4 h, according to the ultrasonography. The antibacterial activity of apigenin against H. pylori was nearly two folds more than the pure apigenin and had a more sustained release in the best microsponge, according to the in vitro MIC data, when compared to pure apigenin. To sum up, the developed gastroretentive microsponge with apigenin offers a viable alternative for the efficient targeting of H. pylori. But more preclinical & clinical studies of our best microsponge would yield considerably more fruitful results.

Helicobacter pylori Infection, Its Laboratory Diagnosis, and Antimicrobial Resistance: a Perspective of Clinical Relevance

Despite the recent decrease in overall prevalence of Helicobacter pylori infection, morbidity and mortality rates associated with gastric cancer remain high. The antimicrobial resistance developments and treatment failure are fueling the global burden of H. pylori-associated gastric complications. Accurate diagnosis remains the opening move for treatment and eradication of infections caused by microorganisms. Although several reports have been published on diagnostic approaches for H. pylori infection, most lack the data regarding diagnosis from a clinical perspective. Therefore, we provide an intensive, comprehensive, and updated description of the currently available diagnostic methods that can help clinicians, infection diagnosis professionals, and H. pylori researchers working on infection epidemiology to broaden their understanding and to select appropriate diagnostic methods. We also emphasize appropriate diagnostic approaches based on clinical settings (either clinical diagnosis or mass screening), patient factors (either age or other predisposing factors), and clinical factors (either upper gastrointestinal bleeding or partial gastrectomy) and appropriate methods to be considered for evaluating eradication efficacy. Furthermore, to cope with the increasing trend of antimicrobial resistance, a better understanding of its emergence and current diagnostic approaches for resistance detection remain inevitable.

Sitafloxacin for Third-Line Helicobacter pylori Eradication: A Systematic Review

BACKGROUND AND AIM

Sitafloxacin-based therapy is a potent candidate for third-line Helicobacter pylori eradication treatment. In this systematic review, we summarise current reports with sitafloxacin-based therapy as a third-line treatment.

METHODS

Clinical studies were systematically searched using PubMed, Cochrane library, Web of Science, and the Igaku-Chuo-Zasshi database. We combined data from clinical studies using a random-effects model and calculated pooled event rates, 95% confidence intervals (CIs), and the pooled odds ratio (OR).

RESULTS

We included twelve clinical studies in the present systematic review. The mean eradication rate for 7-day regimens of either PPI (proton pump inhibitor) or vonoprazan-sitafloxacin-amoxicillin was 80.6% (95% CI, 75.2-85.0). The vonoprazan-sitafloxacin-amoxicillin regimen was significantly superior to the PPI-sitafloxacin-amoxicillin regimen (pooled OR of successful eradication: 6.00; 95% CI: 2.25-15.98, p < 0.001). The PPI-sitafloxacin-amoxicillin regimen was comparable with PPI-sitafloxacin-metronidazole regimens (pooled OR: 1.06; 95% CI: 0.55-2.07, p = 0.86).

CONCLUSIONS

Although the 7-day regimen composed of vonoprazan, sitafloxacin, and amoxicillin is a good option as the third-line Helicobacter pylori eradication treatment in Japan, the extension of treatment duration should be considered to further improve the eradication rate. Considering the safety concern of fluoroquinolones, sitafloxcin should be used after confirming drug susceptibility.

The Potential Benefits of Vonoprazan as Helicobacter pylori Infection Therapy

Helicobacter pylori infection is a severe global health problem that is closely associated with acid-related diseases and gastric malignancies. Eradicating H. pylori is strongly recommended for lowering peptic ulcer recurrence and preventing gastric cancer. The current approved H. pylori eradication regimen combines a proton pump inhibitor (PPI) with two antibiotics. Unfortunately, this regimen failed to meet expectations mostly due to antibiotic resistance and insufficient gastric acid suppression. Vonoprazan, a novel potassium-competitive acid blocker, showed promising results as a PPI replacement. Vonoprazan inhibits gastric acid secretion by acting as a reversible competitive inhibitor against potassium ions and forming disulfide bonds with the cysteine molecule of H⁺/K⁺-ATPase. Vonoprazan has superior pharmacological characteristics over PPI, such as no requirement for acid activation, stability in acidic conditions, shorter optimum acid suppression period, and resistance to cytochrome P (CYP)2C19 polymorphism. Several comparative randomized controlled trials and meta-analyses revealed the superiority of vonoprazan in eradicating H. pylori, notably the resistant strains. The adverse effect caused by vonoprazan is long-term acid suppression that may induce elevated gastrin serum, hypochlorhydria, and malabsorption. All vonoprazan studies have only been conducted in Japan. Further studies outside Japan are necessary for universally conclusive results.

Discovery of a Novel Mutation in DNA Gyrase and Changes in the Fluoroquinolone Resistance of Helicobacter pylori over a 14-Year Period: A Single Center Study in Korea

The efficacy of fluoroquinolone-based eradication therapy largely depends on the fluoroquinolone resistance of H. pylori. The aim of this study was to investigate the changes in the primary resistance rate of H. pylori to fluoroquinolone and the mechanism of resistance in Korea. A total of 153 strains and 48 strains of H. pylori were isolated at a tertiary hospital in 2005/2006 and 2017/2018, respectively. The minimum inhibitory concentrations (MICs) of fluoroquinolone were determined by the serial 2-fold agar dilution method. DNA sequences in the quinolone resistance-determining regions of gyrA/gyrB were analyzed in resistant strains. Subsequent natural transformation study was performed to determine the association between gyrase mutation and resistance. The resistance rates increased from 19.0% (29/153) to 43.8% (21/48) both for levofloxacin and moxifloxacin. The MIC values for resistant strains increased from 2–8 µg/mL to 4–16 µg/mL over time. Mutation of gyrA was detected in 93.1% (27/29) and 100% (21/21) among the resistant strains in both periods, respectively. A novel Gly-85 mutation of gyrA was found and confirmed to be associated with fluoroquinolone resistance. Fluoroquinolone resistance rate of H. pylori has markedly increased over time in Korea. The resistance is mostly due to the point mutation of gyrA. Fluoroquinolone-containing regimens should be carefully selected in Korea, considering the increasing fluoroquinolone resistance.

Herbal medicine as an auspicious therapeutic approach for the eradication of Helicobacter pylori infection: A concise review

Helicobacter pylori (H. pylori) causes gastric mucosa inflammation and gastric cancer mostly via several virulence factors. Induction of proinflammatory pathways plays a crucial role in chronic inflammation, gastric carcinoma, and H. pylori pathogenesis. Herbal medicines (HMs) are nontoxic, inexpensive, and mostly anti-inflammatory reminding meticulous emphasis on the elimination of H. pylori and gastric cancer. Several HM has exerted paramount anti-H. pylori traits. In addition, they exert anti-inflammatory effects through several cellular circuits such as inhibition of 5'-adenosine monophosphate-activated protein kinase, nuclear factor-κB, and activator protein-1 pathway activation leading to the inhibition of proinflammatory cytokines (interleukin 1α [IL-1α], IL-1β, IL-6, IL-8, IL-12, interferon γ, and tumor necrosis factor-α) expression. Furthermore, they inhibit nitrous oxide release and COX-2 and iNOS activity. The apoptosis induction in Th1 and Th17-polarized lymphocytes and M2-macrophagic polarization and STAT6 activation has also been exhibited. Thus, their exact consumable amount has not been revealed, and clinical trials are needed to achieve optimal concentration and their pharmacokinetics. In the aspect of bioavailability, solubility, absorption, and metabolism of herbal compounds, nanocarriers such as poly lactideco-glycolide-based loading and related formulations are helpful. Noticeably, combined therapies accompanied by probiotics can also be examined for better clearance of gastric mucosa. In addition, downregulation of inflammatory microRNAs (miRNAs) by HMs and upregulation of those anti-inflammatory miRNAs is proposed to protect the gastric mucosa. Thus there is anticipation that in near future HM-based formulations and proper delivery systems are possibly applicable against gastric cancer or other ailments because of H. pylori.

Dynamics of antimicrobial resistance of Helicobacter pylori isolates in the Smolensk region of Russian Federation

BACKGROUND

Efficacy of Helicobacter pylori eradication therapy depends on the chance of having a resistant H. pylori strain, which is ultimately related to the local antimicrobial resistance epidemiology.

AIM

To assess H. pylori resistance to clarithromycin, amoxicillin, metronidazole, levofloxacin, and tetracycline in adult patients in the Smolensk region of Russian Federation over a 9-year period.

MATERIALS AND METHODS

Biopsy samples were taken from the gastric antrum and body of 573 and 210 patients with dyspepsia symptoms and positive rapid urease test during esophagogastroduodenoscopy in 2015-2017 and 2009-2010, respectively. Antimicrobial susceptibility testing was performed for clarithromycin, amoxicillin, metronidazole, levofloxacin, and tetracycline by the agar dilution method.

RESULTS

A total of 143 strains of H. pylori isolated during 2015-2017 and 133 strains isolated during 2009-2010 were tested. Culture success rates were 30% vs 64% for the two periods. Over the 2015-2017, the prevalence of resistance to clarithromycin was 6.3%, to amoxicillin 1.4%, to metronidazole 23.8%, to levofloxacin 24.5%, and to tetracycline 0.7%. Over the 2009-2010, the corresponding resistance rates were 5.3%, 4.5%, 3.8%, 8.3%, and 0%, respectively. There were no significant increases in resistance to clarithromycin, amoxicillin, and tetracycline (P > 0.05) over the 9 years period. Significant increase in resistance to levofloxacin (8.3% in 2009-2010% vs 24.5% in 2015-2017, P < 0.01) and metronidazole (3.8% in 2009-2010% vs 23.8% in 2015-2017, P < 0.01) was observed.

CONCLUSIONS

H. pylori resistance to clarithromycin remained low in the Smolensk region of Russian Federation between 2009 and 2017. Resistance to levofloxacin and metronidazole increased between 2009 and 2017.

Microarray-Based Detection and Clinical Evaluation for Helicobacter pylori Resistance to Clarithromycin or Levofloxacin and the Genotype of CYP2C19 in 1083 Patients

Background. Helicobacter pylori (H. pylori) is one of the most frequent and persistent bacterial infections that affect nearly half of the world's population. Antibiotic resistance is a constantly evolving process and local surveillance of antibiotic resistance is warranted to guide clinicians in their choice of therapy. The aim of this study was to establish a microarray-based detection to identify H. pylori infection, clarithromycin and levofloxacin susceptibility, and CYP2C19 genetic polymorphism and guide to potential choice of proton pump inhibitor (PPI), antibiotic administration for tailored H. pylori eradication therapy. Methods. By analyzing the sequence of human genomic CYP2C19⁎2 and CYP2C19⁎3 and mutations within the 23S rRNA and gyrA gene regions conferring clarithromycin and levofloxacin resistance, respectively, we developed a microarray for individual therapy detection of H. pylori infection. Plasmids were established as positive or limit of detection (LOD) reference materials. The specificity and sensitivity of the microarray had been performed. And a total of 1083 gastric biopsy samples were tested and the Kappa value had been calculated between the array and Sanger sequencing. We also analyzed the resistance to clarithromycin and levofloxacin in China, as well as the CYP2C19 polymorphisms. Results. The LOD of detecting H. pylori was 10³ CFU/mL and human genome DNA was 2 ng/μL. The detection results of 1083 gastric biopsy samples showed that 691 (63.80%) were H. pylori positive, of which 266 (38.49%) were resistant to clarithromycin, 192 (27.79%) were resistant to levofloxacin, and 61 (8.83%) were resistant to both of them. For the type of CYP2C19 polymorphism, 412 (38.04%) were homozygous fast type (HomEM), 574 (53%) were heterozygous EM (HetEM), and 97 (8.96%) were poor metabolizer (PM). Conclusions. The proposed microarray-based detection has high specificity, sensitivity, and reproducibility for detecting the resistance of clarithromycin or levofloxacin as well as CYP2C19 polymorphism, which may help to improve the clinical eradication rate of H. pylori.

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.

Simultaneous detection of human CYP2C19 polymorphisms and antibiotic resistance of Helicobacter pylori using a personalised diagnosis kit

OBJECTIVES

A personalised diagnosis kit for Helicobacter pylori that employs visual gene chip technology for the simultaneous detection of CYP2C19 polymorphisms and clarithromycin/levofloxacin antibiotic resistance was evaluated.

METHODS

Gastric antrum mucosa biopsy specimens of 394 patients were tested using the kit. DNA sequencing and antibiotic susceptibility testing of the H. pylori were also performed.

RESULTS

In total, 267 (67.8%) of the 394 specimens were positive for H. pylori using the kit and DNA sequencing, and 136 (34.5%) were positive by culturing. For human CYP2C19 and the bacterial 23S rRNA and gyrA genes, the concordance rates were 92.4% (364/394), 96.6% (258/267) and 97.0% (259/267) between the kit and DNA sequencing results, respectively. For clarithromycin and levofloxacin resistance, the concordance rates were 90.4% (123/136) and 81.6% (111/136) between the kit and antibiotic susceptibility testing results.

CONCLUSIONS

The personalised diagnosis kit for H. pylori provides useful information for the choice of proton pump inhibitor and antibiotic in combination therapy.

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.

Effects of patient age and choice of antisecretory agent on success of eradication therapy for Helicobacter pylori infection

The effects of patient age on the efficacy of eradication treatment for Helicobacter pylori (H. pylori) remain unclear. The present study aimed to determine whether age affects eradication therapy involving vonoprazan, a novel potassium-competitive acid blocker (PCAB). We reviewed the cases of 3,261 patients who were administered first-line and second-line H. pylori eradication therapy at Toyoshima Endoscopy Clinic. The first-line treatment was clarithromycin and amoxicillin combined with a proton pump inhibitor (PPI) or a PCAB. The second-line treatment was metronidazole and amoxicillin combined with a PPI or PCAB. The patients were divided into a young to middle-aged group (age ≤50 years) and an older group (age >50 years) as well as into PPI and PCAB groups. The PPI-clarithromycin-amoxicillin regimen demonstrated a significantly lower H. pylori eradication rate than the PCAB-clarithromycin-amoxicillin regimen (p<0.001). With the PPI-clarithromycin-amoxicillin regimen, the eradication rate in the young to middle-aged group was significantly lower than that in the older group (p<0.001). Lastly, age had no impact on the eradication rate of PCAB-based therapy or metronidazole-based therapy. In conclusion, with clarithromycin-based triple therapy, PCAB is a better choice of antisecretory agent compared to PPIs, especially in young to middle-aged patients.

Surveillance of Helicobacter pylori Antibiotic Susceptibility in Indonesia: Different Resistance Types among Regions and with Novel Genetic Mutations

Information regarding Helicobacter pylori antibiotic resistance in Indonesia was previously inadequate. We assessed antibiotic susceptibility for H. pylori in Indonesia, and determined the association between virulence genes or genetic mutations and antibiotic resistance. We recruited 849 dyspeptic patients who underwent endoscopy in 11 cities in Indonesia. E-test was used to determine the minimum inhibitory concentration of five antibiotics. PCR-based sequencing assessed mutations in 23S rRNA, rdxA, gyrA, gyrB, and virulence genes. Next generation sequencing was used to obtain full-length sequences of 23S rRNA, infB, and rpl22. We cultured 77 strains and identified 9.1% with clarithromycin resistance. Low prevalence was also found for amoxicillin and tetracycline resistance (5.2% and 2.6%, respectively). In contrast, high resistance rates to metronidazole (46.7%) and levofloxacin (31.2%) were demonstrated. Strains isolated from Sumatera Island had significantly higher metronidazole resistance than those from other locations. Metronidazole resistant strains had highly distributed rdxA amino acid substitutions and the 23S rRNA A2143G mutation was associated with clarithromycin resistance (42.9%). However, one strain with the highest MIC value had a novel mutation in rpl22 without an A2143G mutation. Mutation at Asn-87 and/or Asp-91 of gyrA was associated with levofloxacin-resistance and was related to gyrB mutations. In conclusions, although this is a pilot study for a larger survey, our current data show that Indonesian strains had the high prevalence of metronidazole and levofloxacin resistance with low prevalence of clarithromycin, amoxicillin, and tetracycline resistance. Nevertheless, clarithromycin- or metronidazole-based triple therapy should be administered with caution in some regions of Indonesia.

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.

Efficacy of 7-Day and 14-Day Bismuth-Containing Quadruple Therapy and 7-Day and 14-Day Moxifloxacin-Based Triple Therapy as Second-Line Eradication for Helicobacter pylori Infection

BACKGROUND/AIMS

Bismuth-containing quadruple and moxifloxacin-based triple regimens are recommended as second-line therapy for Helicobacter pylori infection. The aim of this study was to compare the efficacy of each regimen.

METHODS

From August 2004 to October 2012, a total of 949 patients (mean age, 54.32±12.08 years; male, 49.4%) who failed H. pylori eradication with a standard triple regimen were included. Patients treated with a bismuth-containing quadruple regimen for 7 and 14 days were designated as 7-BMT and 14-BMT, respectively, and those treated with a moxifloxacin-based triple regimen for 7 and 14 days were designated as 7-MA and 14-MA, respectively. H. pylori eradication was confirmed using the (13)C-urea breath test, rapid urease test or histology.

RESULTS

The eradication rates by 7-BMT, 14-BMT, 7-MA, and 14-MA were 66.4% (290/437), 71.1% (113/159), 53.1% (51/96), and 73.5% (189/257), respectively, by intention-to-treat analysis (ITT) and 76.5% (284/371), 83.8% (109/130), 55.6% (50/90), and 80.6% (187/232), respectively, by per-protocol analysis (PP). The eradication rates were higher in 14-BMT than 7-BMT by the ITT and PP analyses (p=0.277 and p=0.082, respectively). The 14-BMT and 14-MA treatments showed similar efficacies by ITT and PP (p=0.583 and p=0.443, respectively).

CONCLUSIONS

The 7-BMT, 14-BMT, and 14-MA treatments showed similar and suboptimal efficacies. In both regimens, extending the duration of treatment may be reasonable considering the high level of antibiotic resistance in Korea.

Review article: the global emergence of Helicobacter pylori antibiotic resistance

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mechanisms of Helicobacter pylori antibiotic resistance and molecular testing

Antibiotic resistance in Helicobacter pylori (H.pylori) is the main factor affecting the efficacy of current treatment methods against infection caused by this organism. The traditional culture methods for testing bacterial susceptibility to antibiotics are expensive and require 10–14 days. Since resistance to clarithromycin, fluoroquinolone, and tetracycline seems to be exclusively caused by specific mutations in a small region of the responsible gene, molecular methods offer an attractive alternative to the above-mentioned techniques. The technique of polymerase chain reaction (PCR) is an accurate and rapid method for the detection of mutations that confer antibiotic resistance. This review highlights the mechanisms of antibiotic resistance in H. pylori and the molecular methods for antibiotic susceptibility testing.

Attempts to enhance the eradication rate of Helicobacter pylori infection

Increasing rates of antimicrobial resistance to clarithromycin and metronidazole present challenges in maintaining optimal eradication rates. Knowledge of local antibiotic resistance and consumption pattern is important in selecting a reliable regimen. In addition, adverse effect profiles of therapeutic regimens are important and must be addressed to enhance compliance rates. Various methods of enhancing the eradication rates of Helicobacter pylori (H. pylori) have been investigated, including changing combinations or durations of established drugs, adding adjuvant drugs, or development of new molecules or agents. Bismuth-containing quadruple, sequential, concomitant, and levofloxacin-based triple therapies are replacing the long-standing standard of the triple regimen. Despite the encouraging results of these regimens, individualized approaches like treatment after antibiotics resistance test or CYP2C19 genotyping would be the mainstream of future therapy. Because scientific, economic, and technical problems make these advance therapies unfit for widespread use, future development for H. pylori therapy should be directed to overcome individualized antibiotic resistance. Although various novel regimens and additive agents have indicated favorable outcomes, more studies or validations are needed to become a mainstream H. pylori therapy.

Molecular approaches and modern clinical strategies for the management of Helicobacter pylori infection in Japan

Thirty years have passed since Warren and Marshall's discovery of Helicobacter pylori (H. pylori). Since then, not only peptic ulcer diseases and chronic gastritis but also non-cardia gastric cancers have been recognized as diseases originating from H. pylori infection. Several combination therapies consisting of multiple antibiotics have been developed as first- or second-line regimens to eradicate H. pylori infection. Our extensive experience in the field of anti-H. pylori medicine suggests that clinicians should consider a possible role for unidentified, invisible pathogens to elucidate the pathogenesis and improve the treatment of refractory diseases of unknown etiology.

Metal complexes of quinolone antibiotics and their applications: an update

Quinolones are synthetic broad-spectrum antibiotics with good oral absorption and excellent bioavailability. Due to the chemical functions found on their nucleus (a carboxylic acid function at the 3-position, and in most cases a basic piperazinyl ring (or another N-heterocycle) at the 7-position, and a carbonyl oxygen atom at the 4-position) quinolones bind metal ions forming complexes in which they can act as bidentate, as unidentate and as bridging ligand, respectively. In the polymeric complexes in solid state, multiple modes of coordination are simultaneously possible. In strongly acidic conditions, quinolone molecules possessing a basic side nucleus are protonated and appear as cations in the ionic complexes. Interaction with metal ions has some important consequences for the solubility, pharmacokinetics and bioavailability of quinolones, and is also involved in the mechanism of action of these bactericidal agents. Many metal complexes with equal or enhanced antimicrobial activity compared to the parent quinolones were obtained. New strategies in the design of metal complexes of quinolones have led to compounds with anticancer activity. Analytical applications of complexation with metal ions were oriented toward two main directions: determination of quinolones based on complexation with metal ions or, reversely, determination of metal ions based on complexation with quinolones.

Synthesis of intervenolin, an antitumor natural quinolone with unusual substituents

Synthesis of intervenolin, a natural quinolone discovered by screening for selective growth inhibitors of cancer cells cocultured with stromal cells over monocultured cells, was achieved. The synthesis utilized a thiocyanate-isothiocyanate rearrangement and Suzuki-Miyaura coupling to furnish the characteristic substituents, the iminodithiocarbonate moiety, and the geranyl side chain, respectively. In vivo studies showed that intervenolin inhibited tumor tissue growth in model mice.

Safety and efficacy of 1-week levofloxacin-based triple therapy in first-line treatment for Helicobacter pylori-related peptic ulcer disease in Kashmir, India

BACKGROUND AND OBJECTIVES

There is no ideal therapy for eradication of Helicobacter pylori infection. We evaluated the efficacy and safety of 1-week triple therapy with rabeprazole, levofloxacin, and tinidazole in a metronidazole resistance prevalent region for eradicating H. pylori infection in patients with gastroduodenal ulcers.

METHODS

This was an open-label, prospective study. Consecutive patients with endoscopy-proven duodenal or gastric ulcer and who were H. pylori-positive were treated with levofloxacin 500 mg once a day, rabeprazole 20 mg twice a day, and tinidazole 500 mg twice daily for 7 days followed by rabeprazole 20 mg OD for 8 weeks. Endoscopy was repeated 8 weeks after the end of therapy to check for ulcer healing and H. pylori status.

RESULTS

One hundred and thirty-one patients with gastroduodenal ulcers (duodenal 118, and gastric 13) were included. Drug compliance was 97.7 %. The eradication rate of H. pylori by intention-to-treat analysis was 85.5 % (95 % confidence interval 79.5-91.5) (112 of 131 patients) and by per-protocol analysis was 91.8 % (95 % confidence interval 86.9-96.7) (112 of 122 patients). Adverse effects were reported in 17 %: abdominal pain in 3.05 %, metallic taste in 6.87 %, and nausea and vomiting in 4.58 %.

CONCLUSIONS

Levofloxacin-tinidazole-based triple therapy was highly effective and safe as a first-line regimen in Indian patients with gastroduodenal ulcer disease associated with H. pylori infection. The regimen was well tolerated.

Recent Insights into Antibiotic Resistance in Helicobacter pylori Eradication

Antibiotics have been useful in the treatment of H. pylori-related benign and malignant gastroduodenal diseases. However, emergence of antibiotic resistance often decreases the eradication rates of H. pylori infections. Many factors have been implicated as causes of treatment failure, but the main antibiotic resistance mechanisms described to date are due to point mutations on the bacterial chromosome, a consequence of a significantly phenotypic variation in H. pylori. The prevalence of antibiotic (e.g., clarithromycin, metronidazole, tetracycline, amoxicillin, and furazolidone) resistance varies among different countries; it appears to be partly determined by geographical factors. Since the worldwide increase in the rate of antibiotic resistance represents a problem of relevance, some studies have been performed in order to identify highly active and well-tolerated anti-H. pylori therapies including sequential, concomitant quadruple, hybrid, and quadruple therapy. These represent a promising alternatives in the effort to overcome the problem of resistance. The aim of this paper is to review the current status of antibiotic resistance in H. pylori eradication, highlighting the evolutionary processes in detail at alternative approaches to treatment in the past decade. The underlying resistance mechanisms will be also followed.

Helicobacter pylori Eradication Therapies in the Era of Increasing Antibiotic Resistance: A Paradigm Shift to Improved Efficacy

With the rising prevalence of antimicrobial resistance, the eradication rates of Helicobacter pylori (H. pylori) with standard treatments are decreasing to unacceptable levels (i.e., ≤80%) in most countries. After these disappointing results, several authorities have proposed that infection with H. pylori should be approached and treated as any other bacterial infectious disease. This implicates that clinicians should prescribe empirical treatments yielding a per protocol eradication of at least 90%. In recent years several treatments producing ≥90% cure rates have been proposed including sequential therapy, concomitant quadruple therapy, hybrid (dual-concomitant) therapy, and bismuth-containing quadruple therapy. These treatments are likely to represent the recommended first-line treatments in the near future. In the present paper, we are considering a series of critical issues regarding currently available means and approaches for the management of H. pylori infection. Clinical needs and realistic endpoints are taken into account. Furthermore, emerging strategies for the eradication of H. pylori and the existing evidence of their clinical validation and widespread applicability are discussed.

Helicobacter pylori Eradication Therapies in the Era of Increasing Antibiotic Resistance: A Paradigm Shift to Improved Efficacy

With the rising prevalence of antimicrobial resistance, the eradication rates of Helicobacter pylori (H. pylori) with standard treatments are decreasing to unacceptable levels (i.e., ≤80%) in most countries. After these disappointing results, several authorities have proposed that infection with H. pylori should be approached and treated as any other bacterial infectious disease. This implicates that clinicians should prescribe empirical treatments yielding a per protocol eradication of at least 90%. In recent years several treatments producing ≥90% cure rates have been proposed including sequential therapy, concomitant quadruple therapy, hybrid (dual-concomitant) therapy, and bismuth-containing quadruple therapy. These treatments are likely to represent the recommended first-line treatments in the near future. In the present paper, we are considering a series of critical issues regarding currently available means and approaches for the management of H. pylori infection. Clinical needs and realistic endpoints are taken into account. Furthermore, emerging strategies for the eradication of H. pylori and the existing evidence of their clinical validation and widespread applicability are discussed.

Dual therapy for third-line Helicobacter pylori eradication and urea breath test prediction

We evaluated the efficacy and tolerability of a dual therapy with rabeprazole and amoxicillin (AMX) as an empiric third-line rescue therapy. In patients with failure of first-line treatment with a proton pump inhibitor (PPI)-AMX-clarithromycin regimen and second-line treatment with the PPI-AMX-metronidazole regimen, a third-line eradication regimen with rabeprazole (10 mg q.i.d.) and AMX (500 mg q.i.d.) was prescribed for 2 wk. Eradication was confirmed by the results of the ¹³C-urea breath test (UBT) at 12 wk after the therapy. A total of 46 patients were included; however, two were lost to follow-up. The eradication rates as determined by per-protocol and intention-to-treat analyses were 65.9% and 63.0%, respectively. The pretreatment UBT results in the subjects showing eradication failure; those patients showing successful eradication comprised 32.9 ± 28.8 permil and 14.8 ± 12.8 permil, respectively. The pretreatment UBT results in the subjects with eradication failure were significantly higher than those in the patients with successful eradication (P = 0.019). A low pretreatment UBT result (≤ 28.5 permil) predicted the success of the eradication therapy with a positive predictive value of 81.3% and a sensitivity of 89.7%. Adverse effects were reported in 18.2% of the patients, mainly diarrhea and stomatitis. Dual therapy with rabeprazole and AMX appears to serve as a potential empirical third-line strategy for patients with low values on pretreatment UBT.

Proton pump inhibitor-amoxicillin-clarithromycin versus proton pump inhibitor-amoxicillin-metronidazole as first-line Helicobacter pylori eradication therapy

The aim of this study was to compare the efficacy and tolerability of the first-line Helicobacter pylori (H. pylori) eradication regimen composed of proton pump inhibitor, clarithromycin, and amoxicillin, with those of a regimen composed of proton pump inhibitor, metronidazole, and amoxicillin. Data of patients, who were administered the first-line H. pylori eradication regimen at Tokyo Medical Center between 2008 and 2011, were reviewed. All patients had H. pylori gastritis without peptic ulcer disease. The 7-day triple regimen composed of lansoprazole, clarithromycin, and amoxicillin was administered to 55 patients, and that composed of omeprazole, metronidazole, and amoxicillin was administered to 55 patients. Intention-to-treat and per-protocol eradication rates were 74.5 and 80.4%, respectively, for the regimen of lansoprazole, clarithromycin, and amoxicillin, whereas the corresponding rates were 96.4 and 100%, respectively, for the regimen of omeprazole, metronidazole, and amoxicillin. In conclusion, first-line H. pylori eradication therapy composed of omeprazole, metronidazole, and amoxicillin was significantly more effective than that composed of lansoprazole, clarithromycin, and amoxicillin, without differences in tolerability.

Resistance of Helicobacter pylori strains to antibiotics in Korea with a focus on fluoroquinolone resistance

BACKGROUND AND AIM

New regimens, including those with new fluoroquinolones, have been developed to overcome the antibiotic resistance of Helicobacter pylori. We aimed to assess the antibiotic resistance rates, as well as the molecular mechanisms of fluoroquinolone resistance, of the clinical isolates obtained in Korea.

METHODS

The minimal inhibitory concentration (MIC) values of ciprofloxacin, amoxicillin, clarithromycin, metronidazole and tetracycline were determined by the agar dilution method for 185 treatment-naïve Helicobacter pylori isolates. The resistant strains were evaluated for the presence of point mutations in the quinolone resistance-determining region (QRDR) of the gyrA and gyrB genes by direct nucleotide sequencing.

RESULTS

Twenty-nine (29/185, 15.7%) of the strains were found to be resistant to ciprofloxacin. The resistance rates to amoxicillin, clarithromycin, metronidazole and tetracycline were 2.2% (four of 185), 10.8% (20 of 185), 30.3% (56 of 185) and 0.5% (one of 185), respectively. The most common mutations in the H. pylori gyrA gene were found at codons corresponding to Asp87 (16/29, 55.2%) and Asn91 (10/29, 34.5%).

CONCLUSIONS

Primary H. pylori resistance to ciprofloxacin occurred at a high frequency. The fluoroquinolone resistance is most likely mediated through amino acid point mutation in the gyrA gene at Asn87 and Asp91.

Sitafloxacin resistance in Helicobacter pylori isolates and sitafloxacin-based triple therapy as a third-line regimen in Japan

The third-line treatment regimen for Helicobacter pylori after failure of clarithromycin- and metronidazole-based therapies is not yet established. Sitafloxacin (STX) is a quinolone that possesses potent in vitro activity against H. pylori. In this study, the susceptibility of H. pylori isolates to STX was examined and the efficacy of STX-based triple therapy as a third-line regimen was evaluated. STX showed minimum inhibitory concentrations (MICs) of ≤1 μg/mL against all 100 H. pylori isolates, and the MIC(90) (MIC for 90% of the organisms) of STX was 5 log(2) dilutions lower than that of levofloxacin (LVX). The MIC(50) (MIC for 50% of the organisms) of STX against gyrA mutants was 0.12 μg/mL and was significantly lower than that of LVX (8 μg/mL). The activity of STX at pH 5.5 was significantly less than that at pH 7.0. In the clinical trial, 28 patients with two eradication failures were treated with STX-based triple therapy [rabeprazole 10 mg twice daily (b.i.d.), amoxicillin 750 mg b.i.d. and STX 100mg b.i.d. for 7 days]. The eradication rate was 75% using intention-to-treat analysis and 80% using per-protocol analysis. Two gyrA mutant strains were eradicated. Amongst participants, a low pepsinogen I/II ratio was associated with successful eradication. These results suggest that STX could be active against most clinical H. pylori isolates and that STX-based triple therapy is a promising and safe third-line therapy.

Helicobacter pylori resistance to rifabutin in the last 7 years

A low rate of resistance (0.24%) to rifabutin was noted in Helicobacter pylori strains isolated from 414 Japanese patients. The only rifabutin-resistant strain detected showed a point mutation in the rpoB gene and was isolated from a patient with a history of rifampin treatment for pulmonary tuberculosis.

Numerous risk factors for Helicobacter pylori antibiotic resistance revealed by extended anamnesis: a Bulgarian study

The aim of this study was to assess risk factors for primary Helicobacter pylori antibiotic resistance by an extended anamnesis. In total, 519 H. pylori strains from untreated symptomatic adults who answered a questionnaire were evaluated. Strain susceptibility was assessed by a breakpoint susceptibility test. Primary resistance rates were 29.5 % for metronidazole, 17.9 % for clarithromycin, 7.3 % for metronidazole+clarithromycin, 4.0 % for tetracycline and 10.8 % for ciprofloxacin. On multivariate analysis, younger (≤65 years) age was an independent predictor for metronidazole resistance. To our knowledge, for the first time, being a member of the health-care profession was revealed as a risk factor for H. pylori resistance to metronidazole and both metronidazole and clarithromycin. Respiratory and urinary tract infections were independent predictors of clarithromycin and ciprofloxacin resistance, respectively. The presence of co-infections was an independent risk factor for clarithromycin, metronidazole and ciprofloxacin resistance. Surprisingly, female sex was the only predictor for tetracycline resistance. The antibiotic resistance rates were not associated with disease type, place of residence, birthplace, educational level, non-steroidal anti-inflammatory drug or proton pump inhibitor use, smoking or dietary factors, such as consumption of coffee, yogurt, green tea, raw garlic, raw onion, honey or meat. There was a trend for higher metronidazole resistance in strains from diabetic patients. In conclusion, the extended anamnesis of H. pylori-positive patients should include data on patient age, sex, whether they are in the health-care profession, co-infections and possibly diabetes to improve the choice of empiric therapy. Tailored treatment based on the extended anamnesis is suggested, and susceptibility testing of the strains is recommended for patients at risk for antibiotic resistance, especially to clarithromycin, fluoroquinolones or both metronidazole and clarithromycin.

Enhancement of amoxicillin resistance after unsuccessful Helicobacter pylori eradication

A high rate of resistance (49.5 to 72.7%) to amoxicillin (AMX) was observed in Helicobacter pylori after two or three unsuccessful eradication attempts. Unsuccessful eradication regimens significantly increase resistance to not only clarithromycin (CLR) and metronidazole (MNZ) but also AMX.

Multicenter survey of routine determinations of resistance of Helicobacter pylori to antimicrobials over the last 20 years (1990 to 2009) in Belgium

We analyzed the rates of antimicrobial resistance of Helicobacter pylori strains isolated from patients from 1990 to 2009 and identified risk factors associated with resistance. Gastric biopsy specimens were collected from several digestive disease centers in Brussels, Belgium. We routinely performed antimicrobial susceptibility testing for clarithromycin (CLR), metronidazole, amoxicillin, tetracycline, and ciprofloxacin. Evaluable susceptibility testing was obtained for 9,430 strains isolated from patients who were not previously treated for Helicobacter pylori infection (1,527 isolates from children and 7,903 from adults) and 1,371 strains from patients who were previously treated (162 isolates from children and 1,209 from adults). No resistance to amoxicillin was observed, and tetracycline resistance was very rare (<0.01%). Primary metronidazole resistance remained stable over the years, with significantly lower rates for isolates from children (23.4%) than for isolates from adults (30.6%). Ciprofloxacin resistance remained rare in children, while it increased significantly over the last years in adults. Primary clarithromycin resistance increased significantly, reaching peaks in 2000 for children (16.9%) and in 2003 for adults (23.7%). A subsequent decrease of resistance rates down to 10% in both groups corresponded to a parallel decrease in macrolide consumption during the same period. Multivariate logistic regression revealed that female gender, age of the patient of 40 to 64 years, ethnic background, the number of previously unsuccessful eradication attempts, and the different time periods studied were independent risk factors of resistance to clarithromycin, metronidazole, and ciprofloxacin. Our study highlights the need to update local epidemiological data. Thus, the empirical CLR-based triple therapy proposed by the Maastricht III consensus report remains currently applicable to our population.

Two-decade trends in primary Helicobacter pylori resistance to antibiotics in Bulgaria

Evaluating long-term trends in antibiotic resistance can predict earlier the short-term changes in resistance patterns. The aim of the present study was to compare primary resistance rates in 501 Helicobacter pylori strains in 2007 to 2009 to those in 1990 to 1995 (179 strains) and the antibiotic MICs to detect the 20-year resistance evolution. In 2007 to 2009, strains from children exhibited lower resistance rates to metronidazole (16.4%) and ciprofloxacin (2.7%) than those from adults (27.3% and 10.3%, respectively). In 2008 to 2009, more children (29.3%) harbored clarithromycin-resistant strains compared to the adults (17.4%). Overall clarithromycin resistance rate (19.4%) in 2007 to 2009 was much higher than that in 1990 to 1995 (6.2%). MIC(90) of erythromycin in 1990 to 1995 was 142.2-fold lower than that of clarithromycin in 2007 to 2009. Clarithromycin MIC(90) increased >42-fold since 2001 to 2004. Quinolone resistance rate increased 7.7-fold, being 9.2% in 2007 to 2009 versus 1.2% in 1990 to 1995, with a 5-fold increase in MIC(90). Conversely, the amoxicillin resistance decreased from 3.2% in 1996 to 1999 to 0.4% in 2007 to 2009. The MIC(90)'s of tetracycline remained stable but MIC(50)'s of both metronidazole and tetracycline before 1996 decreased about 4-fold to 2007 to 2009. In conclusion, associations between the resistance evolution and patients' age groups as well as the national outpatient antibiotic use have been found. H. pylori resistance to antibiotics showed many long-term changes, with a more rapid evolution for clarithromycin than for the other antibiotics. Metronidazole and tetracycline did not show a resistance evolution but exhibited a decrease in MIC(50) since 1990. The significant increase in ciprofloxacin resistance was found only by extending the study period to 20 years.

Geographic map and evolution of primary Helicobacter pylori resistance to antibacterial agents

Antibiotic resistance in Helicobacter pylori is the major cause of eradication failure. Primary H. pylori susceptibility patterns, however, are becoming less predictable. Currently, high (> or =20%) clarithromycin resistance rates have been observed in the USA and in developed countries in Europe and Asia, while the highest (> or =80%) metronidazole-resistance rates have been reported in Africa, Asia and South America. Primary quinolone-resistance rates of 10% or more have already been reported in developed countries in Europe and Asia. Primary amoxicillin resistance has been low (0 to <2%) in Europe but higher (6-59%) in Africa, Asia and South America. Similarly, tetracycline resistance has been absent or low (<5%) in most countries and higher (9-27%) in Asia and South America. The increasing clarithromycin and quinolone resistance, and multidrug resistance detected in 0 to less than 5% in Europe and more often (14.2%) in Brazil are worrying. Growing resistance often parallels national antibiotic consumption and may vary within patient groups according to the geographic region, patient's age and sex, type of disease, birthplace, other infections and other factors. The geographic map and evolution of primary H. pylori resistance are clinically important, should be considered when choosing eradication regimens, and should be monitored constantly at national and global levels in an attempt to reach the recently recommended goal of eradication of more than 95%.

Changes in 12-Year First-Line Eradication Rate of Helicobacter pylori Based on Triple Therapy with Proton Pump Inhibitor, Amoxicillin and Clarithromycin

A triple therapy based on a proton pump inhibitor (PPI), amoxicillin (AMPC), and clarithromycin (CAM) is recommended as a first-line therapy for Helicobacter pylori (H. pylori) eradication and is widely used in Japan. However, a decline in eradication rate associated with an increase in prevalence of CAM resistance is viewed as a problem. We investigated CAM resistance and eradication rates over time retrospectively in 750 patients who had undergone the triple therapy as first-line eradication therapy at Nagoya City University Hospital from 1995 to 2008, divided into four terms (Term 1: 1997-2000, Term 2: 2001-2003, Term 3: 2004-2006, Term 4: 2007-2008). Primary resistance to CAM rose significantly over time from 8.7% to 23.5%, 26.7% and 34.5% while the eradication rate decreased significantly from 90.6% to 80.2%, 76.0% and 74.8%. Based on the PPI type, significant declines in eradication rates were observed with omeprazole or lansoprazole, but not with rabeprazole. A decrease in the H. pylori eradication rate after triple therapy using a PPI + AMPC + CAM has been acknowledged, and an increase in CAM resistance is considered to be a factor. From now on, a first-line eradication regimen that results in a higher eradication rate ought to be investigated.

Helicobacter pylori eradication therapy

Helicobacter pylori infection is the main cause of gastritis, gastroduodenal ulcers and gastric cancer. H. pylori eradication has been shown to have a prophylactic effect against gastric cancer. According to several international guidelines, the first-line therapy for treating H. pylori infection consists of a proton pump inhibitor (PPI) or ranitidine bismuth citrate, with any two antibiotics among amoxicillin, clarithromycin and metronidazole, given for 7-14 days. However, even with these recommended regimens, H. pylori eradication failure is still seen in more than 20% of patients. The failure rate for first-line therapy may be higher in actual clinical practice, owing to the indiscriminate use of antibiotics. The recommended second-line therapy is a quadruple regimen composed of tetracycline, metronidazole, a bismuth salt and a PPI. The combination of PPI-amoxicillin-levofloxacin is a good option as second-line therapy. In the case of failure of second-line therapy, the patients should be evaluated using a case-by-case approach. European guidelines recommend culture before the selection of a third-line treatment based on the microbial antibiotic sensitivity. H. pylori isolates after two eradication failures are often resistant to both metronidazole and clarithromycin. The alternative candidates for third-line therapy are quinolones, tetracycline, rifabutin and furazolidone; high-dose PPI/amoxicillin therapy might also be promising.

Homology model of the DNA gyrase enzyme of Helicobacter pylori, a target of quinolone-based eradication therapy

BACKGROUND AND AIMS

Resistance of Helicobacter pylori to the standard therapeutic antimicrobial agents has been demonstrated. Although quinolones are an alternative candidate for third-line eradication therapy, quinolone resistance of H. pylori is also increasing. Quinolone resistance of H. pylori is caused by a point mutation of the DNA gyrase subunit A (GyrA) protein, especially on amino acids 87 and 91. The aim of this study is to surmise the structure of H. pylori GryA.

METHODS

The modeling of the 3-D structure of H. pylori GyrA was performed by an automated homology modeling program: SWISS-MODEL. The position of amino acids 87 and 91 in H. pylori GyrA was plotted on the homology model. To estimate the function of quinolone resistance-determining region (QRDR), the structure of H. pylori GyrA was compared with Escherichia coli GyrA.

RESULTS

A molecular model of H. pylori GyrA could be predicted using SWISS-MODEL. The GyrA N- and C-terminal domains closely resembled those of E. coli. The position of amino acids 87 and 91 in H. pylori GyrA was part of the DNA binding region (head dimer interface) on the GyrA N-terminal domain.

CONCLUSION

Our homology model of H. pylori GryA suggests that the quinolone resistance-determining region is on the head dimer interface of the GyrA N-terminal domain.

Second-line rescue therapy of helicobacter pylori infection

Helicobacter pylori infection is the main known cause of gastritis, gastroduodenal ulcer disease and gastric cancer. After more than 20 years of experience in H. pylori treatment, however, the ideal regimen to treat this infection has still to be found. Nowadays, apart from having to know well first-line eradication regimens, we must also be prepared to face treatment failures. Therefore, in designing a treatment strategy we should not focus on the results of primary therapy alone, but also on the final (overall) eradication rate. The choice of a 'rescue' treatment depends on which treatment is used initially. If a first-line clarithromycin-based regimen was used, a second-line metronidazole-based treatment (quadruple therapy) may be used afterwards, and then a levofloxacin-based combination would be a third-line 'rescue' option. Alternatively, it has recently been suggested that levofloxacin-based 'rescue' therapy constitutes an encouraging second-line strategy, representing an alternative to quadruple therapy in patients with previous PPI-clarithromycin-amoxicillin failure, with the advantage of efficacy, simplicity and safety. In this case, quadruple regimen may be reserved as a third-line 'rescue' option. Finally, rifabutin-based 'rescue' therapy constitutes an encouraging empirical fourth-line strategy after multiple previous eradication failures with key antibiotics such as amoxicillin, clarithromycin, metronidazole, tetracycline, and levofloxacin. Even after two consecutive failures, several studies have demonstrated that H. pylori eradication can finally be achieved in almost all patients if several 'rescue' therapies are consecutively given. Therefore, the attitude in H. pylori eradication therapy failure, even after two or more unsuccessful attempts, should be to fight and not to surrender.

Helicobacter pylori and gastric cancer

Helicobacter pylori is now well known as an important pathogen related to the development of gastric cancer. However, some clinicians still doubt the causal association of H. pylori with the development of gastric cancer. To summarize the recent clinical data on the link between H. pylori and gastric cancer, we reviewed related articles published over the past 3 years, after the award of the Nobel Prize for Physiology or Medicine to Drs. J.R. Warren and B.J. Marshall for the first culture and isolation of H. pylori and the investigation of their relevance to peptic ulcer disease. This updated summary of the relationship between H. pylori and gastric cancer highlights the strong link between the organism and the development of gastric cancer, and suggests eradication of this bacterial infection as a possible prophylactic measure against the development of this lethal malignancy. At present, clinicians and researchers in the field emphasize the strong need for H. pylori eradication from the human stomach.