Helicobacter pylori isolated from patients who later failed H. pylori eradication triple therapy readily develop resistance to clarithromycin

Using next-generation sequencing to analyze Helicobacter pylori clones with different levofloxacin resistances from a patient with eradication failure

The regimens containing levofloxacin (LVX) have been recommended as an alternate to standard triple therapy to treat Helicobacter pylori infections and H pylori mixed infection always lead to H pylori chronic infection. Although the molecular mechanism of LVX resistance with gyrA gene mutation has been clearly understood in H pylori, other genes involved in antibiotic resistance remain unclear. Efflux pump plays an important role in clinically relevant multidrug resistance. Furthermore, the relationship between the strains with different LVX level-resistances from individuals is also unknown.Helicobacter pylori monoclonal strains were isolated from patients with eradication failure. E test was used to detect the minimal inhibitory concentration of LVX. One lower-level LVX-resistant clone and 2 higher-level LVX-resistant clones from the same patient were selected to sequence the complete genomes. Single-nucleotide variants (SNVs) and mutations were extracted and analyzed from gryA and resistance-nodulation-division family efflux genes.Two clones with higher-level resistance had the mutation pattern of Asn87Lys and one lower-level LVX-resistant clone had an Asp91Asn mutation. Compared to clones with higher-level resistance, the higher genetic variations were found in genes belonging to the resistance-nodulation-division family in H pylori strains with lower-level resistance to LVX. There were significantly more SNVs of Hp0970 (hefE) and Hp1329 (hefI) in the lower-level LVX-resistant clone than those in the higher-level LVX-resistant clones (P = .044).The mutation pattern of the Asn87Lys of the gyrA gene confers a higher resistance to LVX than that of the Asp91Asn in H pylori. Increase in the number of SNVs of the Hp0970 (hefE) and Hp1329 (hefI) genes change the resistance to LVX. Twelve mutations verified by Sanger sequencing in Hp0970 (hefE) and Hp1329 (hefI) may decrease resistant levels to LVX.

Hydrogen Peroxide-Mediated Oxygen Enrichment Eradicates Helicobacter pylori In Vitro and In Vivo

Helicobacter pylori is an important risk factor for gastric ulcers. However, antibacterial therapies increase the resistance rate and decrease the eradication rate of H. pylori Inspired by the microaerophilic characteristics of H. pylori, we aimed at effectively establishing an oxygen-enriched environment to eradicate and prevent the recurrence of H. pylori The effect and the mechanism of an oxygen-enriched environment in eradicating H. pylori and preventing the recurrence were explored in vitro and in vivo During oral administration and after drug withdrawal, H. pylori counts were evaluated by Giemsa staining in animal cohorts. An oxygen-enriched environment in which H. pylori could not survive was successfully established by adding hydrogen peroxide into several solutions and rabbit gastric juice. Hydrogen peroxide effectively killed H. pylori in Columbia blood agar and special peptone broth. Minimum inhibition concentrations and minimum bactericidal concentrations of hydrogen peroxide were both relatively stable after promotion of resistance for 30 generations, indicating that hydrogen peroxide did not easily promote resistance in H. pylori In models of Mongolian gerbils and Kunming mice, hydrogen peroxide has been shown to significantly eradicate and effectively prevent the recurrence of H. pylori without toxicity and damage to the gastric mucosa. The mechanism of hydrogen peroxide causing H. pylori death was related to the disruption of bacterial cell membranes. The oxygen-enriched environment achieved by hydrogen peroxide eradicates and prevents the recurrence of H. pylori by damaging bacterial cell membranes. Hydrogen peroxide thus provides an attractive candidate for anti-H. pylori treatment.

Effects of Clarithromycin-Containing Quadruple Therapy on Helicobacter Pylori Eradication after Nitroimidazole-Containing Quadruple Therapy Failure

BACKGROUND

Several large clinical trials and meta-analyses have shown about 20% failure to eradicate Helicobacter pylori (H.pylori), necessitating investigations for second-line treatments. The aim of this study was to evaluate the effects of clarithromycin-containing quadruple regimen after nitroimidazole-containing quadruple therapy failure.

METHODS

Thirty two patients who had failed 10-day H.pylori treatment with omeprazole, amoxicillin, bismuth subcitrate, and metronidazole (OABM) regimen and 31 patients who had failed 10-day treatment with omeprazole, amoxicillin, bismuth subcitrate, and furazolidone (OAMF) regimen entered the study. They all received omeprazole (20 mg), amoxicillin (1 gr), bismuth subcitrate (240 mg) and clarithromycin (500 mg) twice a day for 10 days. Eight weeks after treatment, H. pylori eradication was assessed by ¹⁴C-urea breath test.

RESULTS

Totally 61 patients completed the study. According to intention to treat (ITT) analysis, eradication rates by second-line OABC regimen were 84.37% (95% CI= 71.7–96.9%) in OABM group and 77.41% (95% CI= 62.71–92.11%) in OABF group (p=0.756). Per-protocol (pp) eradication rates were 87.09% (95% CI= 75.2–98.8%) and 82.75% (95% CI= 79.4–96%), respectively (p=0.638). Also the cumulative eradication rates by OABC regimen were 80.9% (95% CI= 71.2–90.6%) and 85% (95% CI= 75.9–94%) according to ITT and PP analyses, respectively. Severe side effects were reported in 3.1% of the patients.

CONCLUSION

Regarding ideal eradication rate (>80%) and very low adverse effects, it seems that clarithromycin-containing quadruple therapy can be an encouraging regimen after nitroimidazole-containing regimen failure.

Is levofloxacin-based triple therapy an alternative for first-line eradication of Helicobacter pylori? A systematic review and meta-analysis

OBJECTIVES

To evaluate the available data on the efficacy and safety of levofloxacin-based triple therapy compared with standard triple therapy in first-line treatment for Helicobacter pylori infection.

METHODS

By searching MEDLINE, The Cochrane Central Register of Controlled Trials, and Web of Knowledge, two independent reviewers systemically identified randomized controlled trials comparing levofloxacin-based triple regimen with standard triple therapy for first-line treatment of H. pylori infection. The pooled risk ratios (RR) and 95% confidence intervals were calculated.

RESULTS

Overall, nine randomized controlled trials including 1275 patients have been treated with levofloxacin-based triple therapy and 1237 patients with standard regimen. Eradication rate in the levofloxacin-based therapy group was slightly higher than that in the standard triple therapy group regardless of treatment duration (80.2% vs. 77.4%, RR=1.03, 95% CI=0.94-1.13). Subgroup analysis related to different geographic areas found that efficacy of 7-day standard triple regimen was statistically superior to 7-day levofloxacin-based scheme in Asian group (RR=0.91, 95% CI=0.86-0.97), but levofloxacin-based triple therapy was predominant regardless of treatment time in European countries (RR=1.15, 95% CI=1.06-1.23). There was no significant difference between two groups in the incidence of overall adverse events or in the occurrence of discontinuing therapy due to side effects.

CONCLUSIONS

The 10-day levofloxacin-based triple therapy may be considered as an alternative for increasing cure rate of H. pylori infection in European areas. But in Asian countries, standard triple regimen is still superior to levofloxacin-based therapy as first-line regimen for H. pylori eradication.

Second and third line treatment options for Helicobacter pylori eradication

Helicobacter pylori is a highly successful bacterium with a high global prevalence and the infection carries significant disease burden. It is also becoming increasingly difficult to eradicate and the main reason for this is growing primary antibiotic resistance rates in a world where antibiotics are frequently prescribed and readily available. Despite knowing much more about the bacterium since its discovery, such as its genomic makeup and pathogenesis, we have seen declining treatment success. Therefore, clinicians today must be prepared to face one, two or even multiple treatment failures, and should be equipped with sufficient knowledge to decide on the appropriate salvage therapy when this happens. This article discusses the factors contributing to treatment failure and reviews the second and third-line treatment strategies that have been investigated. Established empiric second line treatment options include both bismuth based quadruple therapy and levofloxacin based triple therapy. Antibiotic testing is recommended prior to initiating third line treatment. In the event that antibiotic susceptibility testing is unavailable, third line treatment options include rifabutin, rifaximin and sitafloxacin based therapies.

Efficacy of bismuth-containing quadruple therapies for clarithromycin-, metronidazole-, and fluoroquinolone-resistant Helicobacter pylori infections in a prospective study

BACKGROUND & AIMS

We assessed the efficacy and safety of 4 bismuth-containing quadruple regimens as empiric therapies for Helicobacter pylori infections in patients who did not respond to previous treatment.

METHODS

We performed a prospective single-center study of 424 patients with H pylori infection that was not eradicated by previous therapies. Patients were assigned randomly to groups given lansoprazole (30 mg twice daily) and bismuth potassium citrate (220 mg twice daily), along with 500 mg tetracycline and 400 mg metronidazole 4 times daily (LBTM), 500 mg tetracycline and 100 mg furazolidone 3 times daily (LBTF), 1000 mg amoxicillin 3 times and 500 mg tetracycline 4 times daily (LBAT), or 1000 mg amoxicillin and 100 mg furazolidone 3 times daily (LBAF). Eradication was assessed by a (13)C-urea breath test. Antimicrobial susceptibility was assessed in 188 patients by the agar dilution method.

RESULTS

Per-protocol rates of H pylori eradication were greater than 90% for all regimens: 93.1% for LBTM (95% confidence interval [CI], 88.1%-98.0%), 96.1% for LBTF (95% CI, 92.4%-99.8%), 94.6% for LBAT (95% CI, 90.0%-99.2%), and 99.0% for LBAF (95% CI, 97.0%-100%). The intention-to-treat response rates were 87.9% for LBTM (95% CI, 81.7%-94.0%), 91.7% for LBTF (95% CI, 87.1%-96.3%), 83.8% for LBAT (95% CI, 76.8%-90.9%), and 95.2% for LBAF (95% CI, 91.1%-99.3%). Significantly more patients had infections eradicated by furazolidone-containing regimens than nonfurazolidone regimens (P = .01). Side effects occurred in 33.6% of subjects and occurred significantly more frequently in the LBTM group than the other 3 groups (vs LBTF, P = .006; vs LBAT, P = .003; vs LBAF, P = .02). Metronidazole resistance was 96.8%; no isolates were resistant to amoxicillin, tetracycline, or furazolidone.

CONCLUSIONS

Four bismuth-containing quadruple therapies achieved greater than 90% eradication of H pylori in patients who did not respond to previous treatment, including patients with metronidazole resistance. For patients allergic to penicillin, tetracycline and either metronidazole- or furazolidone-containing regimens are recommended. ClincialTrials.gov number, NCT01668927.

Prevalence of primary and secondary antimicrobial resistance of Helicobacter pylori in Korea from 2003 through 2012

BACKGROUND

Antimicrobial resistance of Helicobacter pylori (H. pylori) affects the efficacy of eradication therapy. The aim of this study was to estimate the prevalence of primary and secondary resistance of H. pylori isolates to antibiotics and to characterize the risk factors associated with antimicrobial resistance in Korea.

MATERIALS AND METHODS

This study was performed during the period of 2003-2012. Primary resistance was evaluated from 347 patients without any history of eradication, and secondary resistance was evaluated in 86 patients from whom H. pylori was cultured after failure of eradication. Minimal inhibitory concentration test was performed for amoxicillin, clarithromycin, metronidazole, tetracycline, azithromycin, levofloxacin, and moxifloxacin using agar dilution method. Primary and secondary resistance rates of H. pylori to 7 antibiotics were evaluated and risk factors for the antibiotic resistance were analyzed.

RESULTS

Increase in the primary resistance rate was found in amoxicillin (6.3-14.9%, p = .051), clarithromycin (17.2-23.7%, p = .323), and both of levofloxacin and moxifloxacin (4.7-28.1%, p = .002) during the study period. Secondary resistance rate significantly increased in metronidazole, levofloxacin, and moxifloxacin. Increase of resistance occurred after initial failure of eradication therapy in case of clarithromycin (p < .001), azithromycin (p < .001), levofloxacin (p = .011), and moxifloxacin (p = .020). Multivariable analyses showed that clarithromycin, azithromycin, levofloxacin, and moxifloxacin resistance was associated with previous eradication treatment history.

CONCLUSIONS

The increased primary and secondary antibiotic resistance of H. pylori in Korea is ongoing, and it will become a significant limitation for effective eradication of H. pylori in the future.

Enzymic colorimetry-based DNA chip: a rapid and accurate assay for detecting mutations for clarithromycin resistance in the 23S rRNA gene of Helicobacter pylori

Macrolide drugs, such as clarithromycin (CAM), are a key component of many combination therapies used to eradicate Helicobacter pylori. However, resistance to CAM is increasing in H. pylori and is becoming a serious problem in H. pylori eradication therapy. CAM resistance in H. pylori is mostly due to point mutations (A2142G/C, A2143G) in the peptidyltransferase-encoding region of the 23S rRNA gene. In this study an enzymic colorimetry-based DNA chip was developed to analyse single-nucleotide polymorphisms of the 23S rRNA gene to determine the prevalence of mutations in CAM-related resistance in H. pylori-positive patients. The results of the colorimetric DNA chip were confirmed by direct DNA sequencing. In 63 samples, the incidence of the A2143G mutation was 17.46 % (11/63). The results of the colorimetric DNA chip were concordant with DNA sequencing in 96.83 % of results (61/63). The colorimetric DNA chip could detect wild-type and mutant signals at every site, even at a DNA concentration of 1.53×102 copies μl−1. Thus, the colorimetric DNA chip is a reliable assay for rapid and accurate detection of mutations in the 23S rRNA gene of H. pylori that lead to CAM-related resistance, directly from gastric tissues.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

“Rescue” regimens after Helicobacter pylori treatment failure

Helicobacter pylori (H pylori) infection is the main cause of gastritis, gastroduodenal ulcer disease, and gastric cancer. After more than 20 years of experience in H pylori treatment, in my opinion, the ideal regimen to treat this infection is still to be found. Currently, apart from having to know first-line eradication regimens well, 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 clarithromycin-based regimen was used initially, a subsequent metronidazole-based treatment (quadruple therapy) may be used afterwards, and then a levofloxacin-based combination would be a third “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, a 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.

Antibiotic resistance of Helicobacter pylori

Helicobacter pylori are spiral-shaped, Gram-negative bacteria that colonize the stomachs of more than half the world's population. H. pylori colonization is the most common cause of chronic active gastritis and peptic ulcer disease, which directly related to gastric carcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. However, the efficacies of eradication therapies are not satisfying mainly because of bacterial resistance to antibiotics. This article makes a brief summary on the recent research related to the antibiotic resistance of H. pylori.

Rapid screening of clarithromycin resistance in Helicobacter pylori by pyrosequencing

Helicobacter pylori infections can be effectively treated with clarithromycin, a macrolide, in combination with other antibiotics, such as amoxicillin, tetracycline or metronidazole. The failure of H. pylori eradication is mainly associated with macrolide-resistant strains. Three point mutations (A2142G/C, A2143G, T2182C) in the peptidyltransferase region of domain V of the 23S rRNA have been described as being associated with clarithromycin resistance. Therefore, the determination of clarithromycin resistance by pyrosequencing was evaluated. H. pylori from 81 gastric biopsies was cultured and clarithromycin resistance was determined by Etest, as well as by pyrosequencing technology (PSQ 96 system; Biotage). The respective mutations were set in relation to the MIC measured in μg ml−1 by Etest. In this study, point mutations in positions 2142 and 2143 were associated with clarithromycin resistance. Mutations in position 2182 did not contribute to clarithromycin resistance. In addition, from 22 out of the 81 biopsies, clarithromycin resistance was determined directly without culturing H. pylori to save additional time. Identical results were obtained as compared to resistance testing with pure H. pylori strains. All results obtained by pyrosequencing were evaluated by Sanger sequencing. The data show that pyrosequencing to detect point mutation is a fast and reliable method for determining clarithromycin resistance in H. pylori, and provides the same results as the Etest.

Eradication therapy for Helicobacter pylori

Eradication therapy for Helicobacter pylori is recommended in a number of clinical conditions. In this article, we discuss the epidemiology and cellular mechanisms that result in antimicrobial resistance, the results of current eradication therapies, and new approaches to the management of Helicobacter pylori infection.

Clinical application progress of Rifaximin in the treatment of digestive diseases

Rifaximin, a derivative of rifamycin, has high antibacterial activity on various kinds of Gram-positive and -negative aerobes and anaerobes, and it is a new drug in the treatment of giardiasis. Rifaximin is not easy to be absorbed after oral administration, and mild systemic adverse reaction is the main characteristic. Recently, Rifaximin has been widely and effectively used in the therapy of many diseases related to intestinal bacterial infection such as hepatic encephalopathy, diverticular disease, overgrowth of intestinal bacteria, inflammatory bowel disease (IBD) and H. pylori infection. The above advances were reviewed in the present article.