In vitro antimicrobial susceptibility of Helicobacter pylori to nine antibiotics currently used in Central Italy

The prevalence of clarithromycin-resistant Helicobacter pylori isolates: a systematic review and meta-analysis

Background

Knowledge of global clarithromycin (CLA)-resistant rates of Helicobacter pylori (H. pylori) is crucial for decision of the most appropriate eradication therapies with good clinical outcomes. Therefore, this review and meta-analysis aimed to evaluate the global prevalence of the CLA resistance in H. pylori to provide some guidance for selecting the first-line antibiotics.

Method

A comprehensive search was performed for relevant literature until April 2021 in PubMed, Embase, and Web of Science databases. Freeman-Tukey double arcsine transformation was performed to estimate the weighted pooled prevalence of resistance.

Results

The meta-analysis included 248 articles. The prevalence of CLA-resistant H. pylori was 27.53% (95% CI [25.41-29.69]). The heterogeneity between reports was significant (I² = 97.80%, P < 0.01). The resistance rate increased from 24.28% in 2010-2017 to 32.14% in 2018-2021 (P < 0.01). Iran, with 38 articles, has the most report. Nevertheless, Switzerland, Portugal, and Israel had the highest resistance rates (67.16%, 48.11%, and 46.12%, respectively). The heterogeneity between the continents and the antimicrobial susceptibility methods also interpreted standard guidelines and breakpoints was insignificant (P > 0.05).

Conclusion

Overall CLA resistance rate was 27.53%, worldwide. The difference in CLA resistance rate among the included studies can be due to several reasons such as differences in antibiotic prescription rates in various geographic areas, use of different breakpoints or inaccurate criteria in performed studies, and the emergence of multidrug-resistant (MDR) strains.

Minimum inhibitory concentrations of commonly used antibiotics against Helicobacter Pylori: A multicenter study in South China

Aim

To determine the minimum inhibitory concentrations (MICs) of commonly used antibiotics against Helicobacter Pylori (H. pylori) in South China and compare their resistance rates by using EUCAST breakpoints and other breakpoints.

Methods

Patients who had not previously received H. pylori treatment in clinical centers in South China were enrolled in this study from 2017 to 2020. Gastric biopsies were obtained for H. pylori culture. The MICs of amoxicillin (AMX), clarithromycin (CLA), metronidazole (MTZ), levofloxacin (LEV), tetracycline (TET) and furazolidone (FZD) were tested by broth microdilution method and assessed by two different breakpoints. ATCC43504 standard strain served as a control.

Results

A total of 208 H. pylori strains were isolated from patients’ biopsy samples. The MICs of AMX, CLA, MTZ, LEV, TET and FZD for H. pylori were 0.0156-256mg/L (MIC₅₀ 0.125mg/L, MIC₉₀ 4mg/L), 0.0156- >256 mg/L (MIC₅₀ 0.0312mg/L, MIC₉₀ 64mg/L), 0.0156- >256mg/L (MIC₅₀ 8mg/L, MIC₉₀ 256mg/L), 0.0156-256mg/L (MIC₅₀ 0.25mg/L, MIC₉₀ 16mg/L), 0.0156-256mg/L (MIC₅₀ 0.0625mg/L, MIC₉₀ 4mg/L), and 0.0156- >256mg/L (MIC₅₀ 0.0312mg/L, MIC₉₀ 2mg/L), respectively. The MICs of AMX, CLA, MTZ, LEV, TET and FZD for ATCC43504 strain were 0.25mg/L, 0.0625mg/L, 64mg/L, 0.5mg/L, 1mg/L and 0.25mg/L, respectively. The resistance rate of FZD was 11.05%. The overall resistance rates according to EUCAST breakpoints and other breakpoints were 57.21% and 14.90% for AMX (p<0.001), 38.94% and 38.94% for CLA (p = 1), 39.42% and 50.96% for MTZ (p<0.001), 12.98% and 10.58% for TET (p = 0.025), 35.10% and 35.10% for LEV (p = 1), respectively.

Conclusions

Our results demonstrate that AMX, FZD, and TET, but not MTZ, CLR or LEV, showed good anti-H. pylori activity in vitro in South China. When different breakpoints were used, similar results were found with CLA, and LEV, but not with AMX, MTZ, or TET.

Rifabutin for the Treatment of Helicobacter Pylori Infection: A Review

Nowadays, apart from having to know first-line Helicobacter pylori eradication regimens well, we must also be prepared to face treatment failures. The aim of this review is to summarize the role of rifabutin in the management of H. pylori infection. Bibliographical searches were performed in PubMed. Data on resistance and efficacy of rifabutin-containing regimens on H. pylori eradication were meta-analyzed. Mean H. pylori rifabutin resistance rate (39 studies, including 9721 patients) was 0.13%; when studies only including patients naïve to H. pylori eradication treatment were considered, this figure was even lower (0.07%). Mean H. pylori eradication rate (by intention-to-treat) with rifabutin-containing regimens (3052 patients) was 73%. Respective cure rates for second-, third-, fourth- and fifth-line therapies, were 79%, 69%, 69% and 72%. Most studies administered rifabutin 300 mg/day, which seemed to be more effective than 150 mg/day. The ideal length of treatment remains unclear, but 10–12-day regimens are generally recommended. Adverse events to rifabutin treatment in H. pylori studies were relatively infrequent (15%), and severe adverse events were exceptional (myelotoxicity was the most significant, although always reversible). In summary, rifabutin-containing therapy represents an encouraging strategy generally restricted, at present, to patients where previous (usually multiple) eradication regimens have failed.

Patterns of quadruple therapy use including bismuth for Helicobacter pylori eradication: A cohort study in the French national claims database

BACKGROUND

Quadruple therapy using a single capsule formulation of bismuth, metronidazole and tetracycline (BMT; Pylera®), associated with omeprazole for the eradication of Helicobacter pylori, represents the reintroduction of bismuth in France after 40 years.

OBJECTIVE

To describe the real-life patterns of use of BMT following a request from the French health authorities.

METHODS

Patients with a first BMT dispensing (index date, ID), with one year of data before and after ID, were identified in the French nationwide claims database 1/97 sample. Misuse of BMT was defined as dispensing>1 pack of BMT at ID or absence of a diagnostic test in the preceding year.

RESULTS

In total, 540 patients were included. Prescribers were gastroenterologists (n=243; 45%) and general practitioners (n=160; 30%). A proton pump inhibitor was co-dispensed to 504 patients (96%). Ten patients (2%) had contraindications to BMT. Fifty-nine patients (11%) met the misuse criteria: ten (2%) were dispensed>1 pack of BMT and 49 (9%) had not had a diagnostic test for H. pylori in the previous year. During follow-up, 27 patients (5%) required retreatment (treatment failure).

CONCLUSION

In this real-life study, most patients were dispensed only one pack of BMT, consistent with recommendations. Misuse related principally to the absence of prior diagnostic test for H. pylori.

Searching for New Tools to Counteract the Helicobacter pylori Resistance: The Positive Action of Resveratrol Derivatives

The drug-resistance phenomenon in Helicobacter pylori underlines the need of novel strategies to improve the eradication rate including alternative treatments combining antibiotic and non-antibiotic compounds with synergistic action. In this study, the antibacterial (MIC/MBC) and anti-virulence effects (biofilm reduction and swarming motility inhibition) of resveratrol-RSV and new synthetized RSV-phenol derivatives, with a higher bioavailability, alone and combined with levofloxacin-LVX were evaluated against resistant H. pylori clinical strains. The experiments were confirmed in vivo using the Galleria mellonella model. Among the studied RSV derivatives, RSV-3 and RSV-4 possessed higher antibacterial activity with respect to RSV (MICs from 6.25 to 200 µg/mL and from 3.12 to 200 µg/mL, respectively). RSV, RSV-3, and RSV-4 were able to synergize with LVX restoring its effect in two out of seven clinical resistant strains tested for the study. RSV, RSV-3, and RSV-4, alone and with LVX at sub-MIC and sub-synergistic concentrations, significantly reduced the biofilm formation. Moreover, RSV-3 and RSV-4 reduced the H. pylori swarming motility on soft agar. RSV, RSV-3, and RSV-4 were non-toxic for G. mellonella larvae and displayed a protective effect against H. pylori infection. Overall, RSV-phenol derivatives should be considered interesting candidates for innovative therapeutic schemes to tackle the H. pylori antibiotic resistance.

Rifabutin-Containing Triple Therapy (RHB-105) for Eradication of Helicobacter pylori: Randomized ERADICATE Hp Trial

Due to increasing resistance to commonly used antibiotics, the World Health Organization and Food and Drug Administration have advocated the development of new therapeutic regimens for Helicobacter pylori (H. pylori). This phase three, double-blind study (ERADICATE Hp) randomized (2:1) treatment-naïve adults with H. pylori infection and dyspepsia to RHB-105 (an all-in-one combination of omeprazole 40 mg, amoxicillin 1000 mg, and rifabutin 50 mg) or an identically-appearing placebo, both administered every 8 h for 14 days. The H. pylori eradication rate with RHB-105, using a modified intent-to-treat (mITT) population of subjects who received ≥1 dose of study drug and had test-of-eradication performed 28-35 days post-completion of therapy, was compared (one-sample Z-test) to a literature-derived comparator rate of 70% and success rate with physician-selected standard-of-care given to placebo failures. The mITT H. pylori eradication rate (95% CI) with RHB-105 of 89.4% (82.0-96.8%) was greater than both the literature-derived comparator rate (P < 0.001) and the standard-of-care rate of 63.0% (44.8-81.1%) (P = 0.006). Adverse events with an incidence ≥5% for RHB-105 were diarrhea (12.7%), headache (11.9%), chromaturia (9.3%), abdominal tenderness (6.8%), and dizziness (5.1%). No leukopenia was noted. RHB-105 (Talicia®) proved to be a safe and effective empiric therapy for H. pylori eradication.

Bovine lactoferrin enhances the efficacy of levofloxacin-based triple therapy as first-line treatment of Helicobacter pylori infection: an in vitro and in vivo study

Objectives

To evaluate the in vitro antimicrobial/antivirulence action of bovine lactoferrin and its ability to synergize with levofloxacin against resistant Helicobacter pylori strains and to analyse the effect of levofloxacin, amoxicillin and esomeprazole with and without bovine lactoferrin as the first-line treatment for H. pylori infection.

Methods

The bovine lactoferrin antimicrobial/antivirulence effect was analysed in vitro by MIC/MBC determination and twitching motility against six clinical H. pylori strains and a reference strain. The synergism was evaluated using the chequerboard assay. The prospective therapeutic trial was carried out on two separate patient groups, one treated with esomeprazole/amoxicillin/levofloxacin and the other with esomeprazole/amoxicillin/levofloxacin/bovine lactoferrin. Treatment outcome was determined with the [¹³C]urea breath test.

Results

In vitro, bovine lactoferrin inhibited the growth of 50% of strains at 10 mg/mL and expressed 50% bactericidal effect at 40 mg/mL. The combination of levofloxacin and bovine lactoferrin displayed a synergistic effect for all strains, with the best MIC reduction of 16- and 32-fold for levofloxacin and bovine lactoferrin, respectively. Bovine lactoferrin at one-fourth MIC reduced microbial motility significantly for all strains studied. In the in vivo study, 6 of 24 patients recruited had treatment failure recorded with esomeprazole/amoxicillin/levofloxacin (75% success, 95% CI 57.68%–92.32%), and in the group with esomeprazole/amoxicillin/levofloxacin/bovine lactoferrin, 2 out of 53 patients recruited had failure recorded (96.07% success, 95% CI 90.62%–101.38%).

Conclusions

Bovine lactoferrin can be considered a novel potentiator for restoring susceptibility in resistant H. pylori strains. Bovine lactoferrin added to a triple therapy in first-line treatment potentiates the therapeutic effect.

Rifabutin-Based Triple Therapy (RHB-105) for Helicobacter pylori Eradication: A Double-Blind, Randomized, Controlled Trial

BACKGROUND

Although consensus supports eradication of Helicobacter pylori infections, antimicrobial resistance has substantially reduced eradication rates with most current therapies.

OBJECTIVE

To assess the effectiveness of a novel rifabutin-based therapy (RHB-105) for H pylori eradication.

DESIGN

Phase 3, double-blind trial (ERADICATE Hp2). (ClinicalTrials.gov: NCT03198507).

SETTING

55 clinical research sites in the United States.

PARTICIPANTS

455 treatment-naive adults with epigastric discomfort and confirmed H pylori infection.

INTERVENTION

RHB-105 (amoxicillin, 3 g; omeprazole, 120 mg; and rifabutin, 150 mg) versus active comparator (amoxicillin, 3 g, and omeprazole, 120 mg), given as 4 capsules every 8 hours for 14 days.

MEASUREMENTS

Between-group difference for H pylori eradication rate, demonstrated by ¹³C urea breath test 4 weeks after treatment, analyzed by using the χ² test.

RESULTS

In the intention-to-treat population, the eradication rate was higher with RHB-105 than with the active comparator (228 vs. 227 patients, respectively; 83.8% [95% CI, 78.4% to 88.0%] vs. 57.7% [95% CI, 51.2% to 64.0%]; P < 0.001). Eradication rates were unaffected by resistance to clarithromycin or metronidazole. No rifabutin resistance was detected. The most commonly reported adverse events (incidence ≥5%) were diarrhea (10.1% with RHB-105 vs. 7.9% with active comparator), headache (7.5% vs. 7.0%), and nausea (4.8% vs. 5.3%).

LIMITATION

Persons of Asian descent were excluded because of their higher prevalence of poor cytochrome P450 2C19 metabolizers.

CONCLUSION

These findings suggest potential for RHB-105 as first-line empirical H pylori therapy, addressing an unmet need in the current environment of increasing antibiotic resistance.

PRIMARY FUNDING SOURCE

RedHill Biopharma Ltd.

Evaluation of Antibiotic Resistance of Helicobacter pylori Strains Isolated in Bari, Southern Italy, in 2017-2018 by Phenotypic and Genotyping Methods

Objective: Helicobacter pylori antibiotic resistance is a constantly evolving process and local surveillance is warranted to guide clinicians in the choice of therapy. Materials and Methods: Antibiotic susceptibility testing was performed by E-test on 92 H. pylori strains, and resistance to clarithromycin and levofloxacin was also evaluated using a commercially available genotyping method. Results: In naïve patients the resistance to clarithromycin, levofloxacin, and metronidazole was 37.7%, 26.2%, and 16.4%, respectively, significantly lower than the percentage found in treated patients. Concomitant resistance to ≥2 antibiotics was also observed in naïve patients. The A2143G mutation of the 23S-rRNA gene was the most frequently detected, also in naïve patients. The highest minimum inhibitory concentration (MIC)₅₀ value (256 mg/L) was associated with A2142 mutations in all the patients carrying them. For levofloxacin resistance a mutation in codon 87 was detected in 63.9% and in codon 91 in 36.1% of the H. pylori strains, without significant differences in the patients groups. A mutation in codon 87 was associated with the highest MIC₅₀ value (32 mg/L). Conclusions: In our area, a high prevalence of H. pylori primary resistance was detected; these rates were higher in patients who had experienced failure of several courses of therapy. A better knowledge of the local epidemiology of resistance, and the genotypes responsible, will improve the H. pylori eradication rates.

First national survey of the diagnosis of Helicobacter pylori infection in Clinical Microbiology Laboratories in Spain

INTRODUCTION

The aim of this study was to know, through a national survey, the methods and techniques used for the diagnosis of Helicobacter pylori (Hp) in the different Clinical Microbiology Services/Laboratories in Spain, as well as antibiotic resistance data.

METHODS

The survey requested information about the diagnostic methods performed for Hp detection in Clinical Microbiology laboratories, including serology, stool antigen, culture from gastric biopsies, and PCR. In addition, the performance of antibiotic susceptibility was collected. Data on the number of samples processed in 2016, positivity of each technique and resistance data were requested. The survey was sent by email (October-December 2017) to the heads of 198 Clinical Microbiology Laboratories in Spain.

RESULTS

Overall, 51 centers from 29 regions answered the survey and 48/51 provided Hp microbiological diagnostic testing. Concerning the microbiological methods used to diagnose Hp infection, the culture of gastric biopsies was the most frequent (37/48), followed by stool antigen detection (35/48), serology (19/48) and biopsy PCR (5/48). Regarding antibiotic resistance, high resistance rates were observed, especially in metronidazole and clarithromycin (over 33%).

CONCLUSION

Culture of gastric biopsies was the most frequent method for detection of Hp, but the immunochromatographic stool antigen test was the one with which the largest number of samples were analyzed. Nowadays, in Spain, it concerns the problem of increased antibiotic resistance to 'first-line' antibiotics.

ANTIBIOTIC RESISTANCE SURVEILLANCE OF HELICOBACTER PYLORI AT THE BIOBÍO REGION (CHILE) IN A DECADE

BACKGROUND

Helicobacter pylori infection in Chile remains as a public and private health-care system's challenge, with a prevalence of the infection over 70%. Nowadays, antibiotic treatment of the infection is mandatory to prevent the arising of severe associated diseases but failures in the eradication therapy mainly due to clarithromycin resistance has been observed worldwide and first line eradication therapy seems to be not effective anymore in several geographical areas. Thus, health-care systems are committed to maintain an epidemiological surveillance upon the evolution of the antibiotic resistance of this priority 2 pathogen.

OBJECTIVE

This work reports a 10 years surveillance of the primary antibiotic resistance of H. pylori clinical isolates at the Biobío region-Chile, and the evolution of resistance toward amoxicillin, clarithromycin, levofloxacin, metronidazole, and tetracycline among the species.

METHODS

H. pylori strains were investigated during the periods 2005-2007 (1435 patients analysed) and 2015-2017 (220 patients analysed) by inoculating a saline homogenate biopsy onto the surface of Columbia agar (Oxoid, Basingstoke, UK) - supplemented with 7% horse red blood cells plus DENT inhibitor (Oxoid, Basingstoke, UK) - following by incubation at 37ºC under 10% CO2 atmosphere for five days. Antibiotic resistance pattern of the isolates was assessed using the disk diffusion test in Müeller-Hinton agar supplemented with 7% horse red blood cells followed by incubation for further three days under 10% CO2 atmosphere. Statistical analysis was done using the SPSS v22 software and P values <0.05 were considered statistically significant.

RESULTS

A total of 41% of 1435 patients were detected to be infected with H. pylori by bacteriological culture in 2005-2007 period, meanwhile 32.7% from 220 patients were also infected in 2015-2017 period. The clinical isolates of H. pylori are mostly susceptible to amoxicillin and tetracycline (both over 98% of strains), but less susceptible to levofloxacin in both periods analysed (over 79% of the strains). On the other hand, metronidazole continuous showing the highest score of resistant isolates (over 40% of resistant strains), although an 18% fewer resistant strains were observed in 2015-2017 period. Clarithromycin, the key antibiotic in eradication therapies, has an increased frequency of resistant strain isolated in the decade (22.5% in 2005-2007 and 29.2% in 2015-2017). Multidrug resistant strains (two, three and four antibiotics) were also detected in both periods with the highest scores for simultaneous resistance to clarithromycin-metronidazole (18%) and clarithromycin-metronidazole-levofloxacin (12.5%) resistant strains. According to gender, the isolates resistant to amoxicillin, clarithromycin and metronidazole were more frequent in female, with a specific increment in amoxicillin and clarithromycin resistance.

CONCLUSION

The frequency of clarithromycin resistance (29.2%) detected in 2015-2017 suggests that conventional triple therapy is no longer effective in this region.

Pylera® plus ranitidine vs Pylera® plus esomeprazole in first-line treatment of Helicobacter pylori infection: Two pilot studies

BACKGROUND

Several studies have shown that Pylera^® (three-in-one capsules containing 140 mg bismuth potassium subcitrate, 125 metronidazole, and tetracycline 125 mg) in association with omeprazole or esomeprazole is a good option in the treatment of Helicobacter pylori infection. In particular, the adjunction of a PPI to Pylera^® may be useful to overcome metronidazole resistance. However, omeprazole and its derivatives can promote greater bismuth absorption and enhance its toxicity. The H2 receptor antagonist (H2RA) ranitidine seems to induce less bismuth absorption and as a consequence less systemic toxicity.

AIM

To evaluate whether Pylera^® in combination with esomeprazole or with ranitidine is equally effective in the treatment of H. pylori infection.

MATERIAL AND METHODS

Two separate groups of patients were treated simultaneously. One group was treated with Pylera^® three capsules qid plus esomeprazole 40 mg bid for 10 days (group A), and the other group was treated with Pylera^® three capsules qid plus ranitidine 300 mg bid for 10 days (group B). H. pylori eradication was defined as a negative result in ¹³ C urea breath test performed at least 8 weeks after the end of treatment with a delta-over-baseline value less than 5.

RESULTS

Thirty-two patients were recruited for group A and thirty-three patients in group B. Eradication rates were 93.7% (30/32) and 90.9% (30/33), respectively, at intention-to-treat analysis, and 96.6% (29/30) and 93.3% (28/30), respectively, at per-protocol analysis. Adverse events occurred in 26 patients and led to the suspension of treatment in one patient in group A and in one patient in group B.

CONCLUSION

The results showed that Pylera® plus a PPI or ranitidine were equally effective in the population studied. The high cure rates of bismuth triple therapy (without an antisecretory drug) and the lack of susceptibility testing make it impossible to exclude the possibility that the results would have been similar if neither the PPI nor the ranitidine were given.

Increasing antimicrobial resistance to clarithromycin and metronidazole in pediatric Helicobacter pylori infection in southern Taiwan: A comparison between two decades

BACKGROUND

Antimicrobial resistance of Helicobacter pylori reduces the eradication rate. This study aimed to investigate changes in antimicrobial susceptibility of H pylori isolated from children in Taiwan in the past two decades.

METHODS

This study enrolled children receiving esophagogastroduodenoscopy for upper gastrointestinal diseases in a national tertiary referring hospital from 1998 to 2018. H pylori infection was diagnosed by culture. The minimal inhibitory concentrations (MICs) of antibiotics were tested using the E test. The antibiotic resistance rates and MICs of amoxicillin, clarithromycin, metronidazole, levofloxacin, and tetracycline were compared between 1998-2008 and 2009-2018.

RESULTS

A total of 70 Helicobacter pylori isolates (29 from 1998 to 2008 and 41 from 2009 to 2018) were identified. The esophagogastroduodenoscopy findings included duodenal ulcers (n = 31), gastric ulcers (n = 9), and gastritis (n = 30). The overall antimicrobial resistance rates of clarithromycin and metronidazole were 22.9% and 21.4%, respectively. The dual resistance rate of clarithromycin and metronidazole was 10%. Resistance rates of levofloxacin and amoxicillin were 8.3% and 2.9%, respectively. None of the isolates were resistant to tetracycline. Compared with the isolates from 1998 to 2008, those from 2009 to 2018 had higher MICs and resistance rates of clarithromycin (26.8% vs 17.2%, P = 0.35) and metronidazole (26.8% vs 13.8%, P = 0.19), but not levofloxacin (9.8% vs 5.3%, P = 1.0) or coresistance to clarithromycin and metronidazole (12.2% vs 6.9%, P = 0.69).

CONCLUSIONS

The antimicrobial resistance rates of pediatric H pylori isolates to clarithromycin and metronidazole increased during the past decade. The selection of antimicrobial agents other than clarithromycin and metronidazole is crucial to increase pediatric H pylori eradication rates.

Molecular characterization and prevalence of antibiotic resistance in Helicobacter pylori isolates in Kuala Lumpur, Malaysia

Aims and objectives

Helicobacter pylori has been classified as high priority pathogen by the WHO in 2017. The emergence of antibiotic-resistant strains is one of the main causes of treatment failure in H. pylori infection. This study determined and characterized primary and secondary resistances in H. pylori in Malaysia.

Materials and methods

Gastric biopsies from antrum (n=288) and corpus (n=283) were obtained from 288 patients who underwent endoscopy at Universiti Kebangsaan Malaysia Medical Center (UKMMC), Kuala Lumpur, Malaysia. Antibiotic susceptibility to six classes of antibiotics was determined by the E-test. Mutations conferring in resistance in functional genes were identified by PCR and sequencing.

Results

Overall resistance rates to metronidazole, clarithromycin and levofloxacin were 59.3% (35/59), 35.6% (21/59) and 25.4% (15/59), respectively. Secondary isolates showed significantly higher resistance rates to clarithromycin compared to the primary isolates. Mixed infection with susceptible and resistant isolates was observed in 16.2% (6/37) of cases, of which 83.3% (n=5) had infection with the same strain. 41% (18/44) of isolates were resistant to more than one class of antibiotics of which 50% (9/18) were multidrug-resistant, two being primary and seven being secondary isolates. Mutations in rdxA, 23S rRNA and gyrA genes were associated with resistance to metronidazole, clarithromycin and levofloxacin, respectively.

Conclusion

The high level of resistance to metronidazole, clarithromycin and levofloxacin seen in H. pylori isolates in our setting warrants the need for continuous surveillance and highlights caution in use of antibiotics generally used as first-line therapy in H. pylori eradication regimen.

Pistacia vera L. oleoresin and levofloxacin is a synergistic combination against resistant Helicobacter pylori strains

The increasing multidrug resistance in Helicobacter pylori, also correlated to its biofilm-forming ability, underlines the need to search novel strategies to improve the eradication rate. Natural compounds are proposed as antibiotic-resistant-breakers capable to restore the efficacy of conventional drugs. Aim of this work was to evaluate the capability of Pistacia vera L. oleoresin (ORS) to synergize with levofloxacin (LVX) against resistant H. pylori strains. The antimicrobial activity of P. vera L. ORS and LVX and their combinations was determined by MIC/MBC (in neutral and acidic environments) and checkerboard tests. The anti-biofilm effect was determined by biomass quantification. In vivo Galleria mellonella model was used to confirm in vitro data. Pistacia vera L. ORS and LVX MICs ranged respectively from 780 to 3120 mg/l and from 0.12 to 2.00 mg/l, at pH 7.0 and 5.5. MBCs were similar to MICs. Pistacia vera L. ORS was able to synergize with LVX, restoring its effectiveness in LVX resistant strains. Pistacia vera L. ORS, LVX and their synergistic combinations displayed significant biofilm reduction. Pistacia vera L. ORS and LVX, showed protective effect against H. pylori infection on G. mellonella (62% and 63% of survival, respectively). Pistacia vera L. ORS can be considered a promising potentiator to restore the effectiveness of LVX tackling the H. pylori antibiotic resistance phenomenon.

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.

Antibiotic resistance pattern of Helicobacter pylori strains isolated in Italy during 2010-2016

PURPOSE

Bacterial resistance toward the most used antibiotics is increasing in Helicobacter pylori strains worldwide. Emergence of multidrug resistance significantly affects the efficacy of standard therapy regimens. Therefore, monitoring for primary antimicrobial resistance is essential for H. pylori management in clinical practice.

METHODOLOGY

H. pylori isolates obtained from patients consecutively observed in a single center were tested for primary resistance by using E-test method. Bacterial strains showing MIC values >0.5, >8 and >1 mg/L toward clarithromycin, metronidazole and levofloxacin, respectively, were considered resistant. The trend of antibiotic prevalence, either single or combined, during 2010-2016 was assessed.

RESULTS

Antibiotic susceptibility data were available in 1424 (82.3%) out of 1730 tested patients. The overall resistance for all the three antibiotics showed an increasing trend from 2010 to 2013 (clarithromycin: from 19% to 35.6%; metronidazole: from 33.6% to 45.3%; levofloxacin: from 19% to 29.7%; p < .001), when a plateau until 2016 was observed (clarithromycin: 35.9%; metronidazole: 40.2%; levofloxacin: 29.3%). A similar trend occurred for clarithromycin-metronidazole combined resistance rate (2010: 11.4%; 2013: 28.2%; 2016: 21.9%).

CONCLUSION

Our data suggest that prevalence of primary resistance in H. pylori isolates toward the most frequently used antibiotics probably reached a plateau in the last years.

Molecular characterization of Helicobacter pylori resistance to rifamycins

INTRODUCTION

Antibiotic resistance is a major contributing factor in treatment failure of Helicobacter pylori eradication. Rifabutin (RB) is a rescue treatment and rifampicin (RP) is used to screen RB resistance in vitro. The aim of this study was to evaluate the rate of rifamycins resistance and to determine the mutations in the rpoB gene conferring resistance to discuss the current break point.

METHODS

Antimicrobial susceptibility to RP was first determined by E-test for 1015 H. pylori isolates. RP and RB MICs were then determined by agar dilution method for strains with MIC of RP > 1 mg/L, and the rpoB gene was sequenced.

RESULTS

Overall, 54 of 1015 strains exhibited a RP MIC > 1 mg/L by agar dilution method. Among these 54 strains, 10 had MICs of RP > 4 mg/L and RB ≥ 1 mg/L. They all carried at least one mutation in the rpoB gene at codons 530, 538, 540, 525 in the RP resistance-determining region (RRDR). Implication of the mutation L547F was confirmed by site-directed mutagenesis experiment. In contrast, among the 44 H. pylori isolates with a MIC of RP comprised between 2 and 4 mg/L, only 4 of 44 (9%) strains exhibited a mutation in rpoB, but outside RRDR (codons 470, 499, 636, or 657). For 31 of 44 tested strains, the RB MICs were ≤0.064 mg/L.

CONCLUSION

These results suggest that H. pylori isolates should be classified as resistant to RP for MICs > 4 mg/L. We considered that the optimal cut off for RB was ≥0.125 mg/L. We report a new mutation responsible for rifamycins, resistance, L547F.

Quadruple, sequential, and concomitant first-line therapies for H. pylori eradication: a prospective, randomized study

BACKGROUND

Current Italian guidelines recommend 10-day bismuth-based or bismuth-free (sequential and concomitant) regimens for first-line H. pylori eradication. However, comparison among these regimens is lacking in our country.

AIM

To perform a 'head-to-head' comparison among these three therapies as first-line treatment for H. pylori eradication in clinical practice.

METHODS

This was a prospective, open-label randomized study enrolling consecutive patients diagnosed with H. pylori infection never previously treated. Patients were randomized to receive one of the following 10-day therapies: (a) Bismuth-based therapy: esomeprazole 20mg b.i.d and Pylera 3 tablets q.i.d; (b) Concomitant therapy: esomeprazole 20mg plus amoxicyllin 1,000mg, clarithromycin 500mg and tinidazole 500mg (all b.i.d.), and (c) Sequential therapy: esomeprazole 20mg plus amoxicyllin 1,000mg for 5days followed by esomeprazole 20mg plus clarithromycin 500mg and tinidazole 500mg for 5days (all b.i.d). H. pylori eradication was assessed by using UBT 4-6 weeks after the end of therapy.

RESULTS

Overall, 187 patients were enrolled. The eradication rates achieved with Pylera, concomitant and sequential were 85.2%, 95.2%, and 93.6%, respectively, at intention to treat, and 94.5%, 96.7%, and 95.1% at per protocol analyses, without a statistically significant difference. The incidence of severe side-effects was higher with the bismuth-based therapy than with the two bismuth-free regimens (9.8% vs 1.6%; p=0.046).

CONCLUSIONS

Bismuth-based and bismuth-free therapies are equally effective for first-line H. pylori eradication. However, bismuth therapy was more frequently interrupted for side-effects than bismuth-free therapies.

Meta-analysis: High-dose vs. low-dose metronidazole-containing therapies for Helicobacter pylori eradication treatment

Objective

The purpose of this study was to evaluate the efficacy of high dose of metronidazole in the treatment of Helicobacter pylori (H. pylori) infection.

Methods

Studies were identified from databases (Pubmed, Embase, Cochrane Library, ClinicalTrials.gov) searched from January 1990 to September 2017 using a battery of keywords. We included randomized controlled trials (RCTs) of H. pylori treatment comparing the high-dose and low-dose metronidazole-containing therapies (high-dose and low-dose therapies). Two reviewers independently selected studies, extracted relevant data and assessed study quality. A meta-analysis was performed by using Review Manager 5.3. Dichotomous data were pooled to obtain the relative risk (RR) of the eradication rate, with 95% confidence intervals (CIs).

Results

Four randomized controlled trials, a total of 612 patients with a diagnosis of H. pylori infection were included. Overall the meta-analysis showed that both high-dose and low-dose therapies achieved similar efficacy of intention-to-treat (ITT) eradication rate 82% vs. 76%, RR 1.12 (95%CI: 0.96 to 1.30), P = 0.15, and adherence 94% vs. 94%, RR 1.00 (95%CI: 0.97 to 1.04), P = 0.81, but side effects were more likely in high-dose therapies [32% vs. 17%, RR 1.84 (95%CI: 1.17 to 2.88), P = 0.008]. In subgroup analysis, increasing the dose of metronidazole enhanced eradication rates in areas with high metronidazole resistance [74% vs 52%, RR 1.40 (95%CI: 1.08 to 1.82), P = 0.01] and in individuals with metronidazole-resistant strains [71% vs. 46%, RR 1.50 (95%CI: 1.02 to 2.19), P = 0.04].

Conclusions

Both high-dose and low-dose therapies can achieve similar eradication rates and adherence and generally low-dose therapies cause fewer side effects. In populations with high metronidazole resistance, high dose of metronidazole can increase the eradication rates of H. pylori infection.

Antibiotic resistance in Helicobacter pylori

PURPOSE OF REVIEW

Treatment of Helicobacter pylori is difficult nowadays because of its high resistance. The prevalence and mechanism of resistance, the different methods to detect it and the clinical implication of resistance were addressed in several research papers last year.

RECENT FINDINGS

Clarithromycin-resistant H. pylori has been recognized by the WHO as 'high priority', for which new antibiotics are needed. Moreover, the Maastricht consensus recommended, in areas with high resistance, that susceptibility tests should be performed, at least after a treatment failure.

SUMMARY

Metronidazole and clarithromycin resistance rates are alarming although they vary among populations. Tetracycline and amoxicillin-resistance are very low in most countries. H. pylori resistance can be detected by phenotypic or by molecular methods. Different break points may be used when performing an antimicrobial susceptibility test, so comparing resistance among different populations is challenging. Genomic techniques open new possibilities in the diagnosis of H. pylori, and the detection of H. pylori and its antimicrobial resistance in faeces is an interesting approach. Eradication rates are dependent on the susceptibility of the strain to metronidazole and clarithromycin, being lower in patients infected with a resistant strain.

Rescue therapy with bismuth quadruple regimen in patients with Helicobacter pylori -resistant strains

BACKGROUND

Bismuth quadruple therapy (BQT) is the recommended rescue therapy for Helicobacter pylori (H. pylori) infection. This study aimed to assess the efficacy and safety of a 10-day BQT regimen in patients who failed previous therapies and were infected with multiresistant H. pylori strains MATERIALS AND METHODS: Helicobacter pylori-infected patients underwent endoscopy, culture, and susceptibility test for clarithromycin, metronidazole, and levofloxacin. Treatment with three-in-one capsule (Pylera®) four times daily and esomeprazole 20 mg twice daily for 10 days was administered. Treatment-emergent adverse events (TEAEs) were registered.

RESULTS

A total of 116 patients with persistent H. pylori infection following at least one eradication therapy attempt were treated. Overall, resistance toward clarithromycin was detected in 80% of strains, toward metronidazole in 70%, and levofloxacin in 47.5%, with dual or triple resistance in 72.5% of cases. An eradication rate of 81.0% (95% CI: 73.0-87.1) and 87.0% (95% CI: 79.4-92.1) at ITT and PP analyses, respectively, was achieved. The cure rate remained high until it was used as fourth-line regimen, while it dropped to low values (<67%) in those patients with more than 4 therapy failures. A total of 65.7% (95% CI: 56.4-74.0) patients complained of TEAEs.

CONCLUSIONS

Our data found that bismuth-based quadruple regimen is effective as rescue therapy for curing patients infected with multiresistant H. pylori strains.

Efficacy and safety of rifaximin associated with standard triple therapy (omeprazole, clarithromycin and amoxicillin) for H. pylori eradication: A phase IV pilot clinical trial

BACKGROUND

A progressive decrease in Helicobacter pylori eradication rates has been described over the years, driving the need for new antibiotic treatments.

AIM

To evaluate the efficacy and safety of the addition of rifaximin (Spiraxin^®) to standard triple therapy (omeprazole, amoxicillin and clarithromycin) for the eradication of H. pylori.

METHODS

Independent prospective clinical trial (EUDRACT no.: 2013-001080-23). Forty consecutive adult patients were included with H. pylori infection, dyspeptic symptoms and naive to eradication treatment. A full blood test was performed in the first five patients enrolled to evaluate the safety of the treatment. H. pylori eradication was confirmed with the ¹³C-urea breath test at least four weeks after the end of treatment with rifaximin 400mg/8h, clarithromycin 500mg/12h, amoxicillin 1g/12h and omeprazole 20mg/12h for 10 days.

RESULTS

Forty patients were consecutively enrolled, 53% woman, mean age 44 years. Indication for eradication: 60% non-investigated dyspepsia, 38% functional dyspepsia and 2% gastric ulcer. Four patients did not attend the eradication confirmatory breath test. The eradication rate was 61% (95% CI: 45-77%) for the protocol and 55% (40-70%) for intention-to-treat. About 76% of the patients experienced adverse events (35% diarrhea, 14% nausea and 24% metallic taste), none of which was serious. The blood tests did not show significant alterations.

CONCLUSION

Acceptable H. pylori eradication rates are not achieved with rifaximin associated with standard triple therapy for 10 days.

Antibiotic susceptibility, heteroresistance, and updated treatment strategies in Helicobacter pylori infection

In this review, we discuss the problem of antibiotic resistance, heteroresistance, the utility of cultures and antibiotic susceptibility tests in Helicobacter pylori (Hp) eradication, as well as the updated treatment strategies for this infection. The prevalence of antibiotic resistance is increasing all over the world, especially for metronidazole and clarithromycin, because of their heavy use in some geographical areas. Heteroresistance (simultaneous presence of both susceptible and resistant strains in different sites of a single stomach) is another important issue, as an isolate could be mistakenly considered susceptible if a single biopsy is used for antimicrobial tests. We also examined literature data regarding eradication success rates of culture-guided and empiric therapies. The empiric therapy and the one based on susceptibility testing, in Hp eradication, may depend on several factors such as concomitant diseases, the number of previous antibiotic treatments, differences in bacterial virulence in individuals with positive or negative cultures, together with local antibiotic resistance patterns in real-world settings. Updated treatment strategies in Hp infection presented in the guidelines of the Toronto Consensus Group (2016) are reported. These suggest to prolong eradication therapy up to 14 days, replacing the old triple therapy with a quadruple therapy based on proton pump inhibitor (PPI), bismuth, metronidazole, and tetracycline for most of the patients, or as an alternative quadruple therapy without bismuth, based on the use of PPI, amoxicillin, metronidazole, and clarithromycin. The new drug vonoprazan, a first-in-class potassium-competitive acid blocker recently approved in Japan, is also considered to be a promising solution for Hp eradication, even for clarithromycin-resistant strains. Furthermore, there is growing interest in finding new therapeutic strategies, such as the development of vaccines or the use of natural resources, including probiotics, plants, or nutraceuticals.

Treatment of Helicobacter pylori infection 2016

Many interesting articles have been published from different parts of the world over the last year assessing various issues around Helicobacter pylori eradication therapy. This article will address the published literature over the last year pertaining to the topic of treatment of H. pylori infection. The main themes that emerge are assessing the efficacy of standard triple therapy, as well as exploring new first-line treatments, mainly optimized nonbismuth-containing and bismuth-containing quadruple therapies with some promising data also emerging on dual therapy. There was also considerable progress in investigating antibiotic resistance rates with much more data emerging from varied parts of the world compared to recent years. Advances in the use of adjunctive therapies, especially probiotic therapies have also been made. Undoubtedly, the eradication of H. pylori remains a worthwhile goal to alleviate the burden of diseases caused by the complications of this infection, including dyspepsia, peptic ulcer disease, and gastric cancer.

Establishment of a nested-ASP-PCR method to determine the clarithromycin resistance of Helicobacter pylori

AIM: To investigate clarithromycin resistance positions 2142, 2143 and 2144 of the 23SrRNA gene in Helicobacter pylori (H. pylori) by nested-allele specific primer-polymerase chain reaction (nested-ASP-PCR).

METHODS: The gastric tissue and saliva samples from 99 patients with positive results of the rapid urease test (RUT) were collected. The nested-ASP-PCR method was carried out with the external primers and inner allele-specific primers corresponding to the reference strain and clinical strains. Thirty gastric tissue and saliva samples were tested to determine the sensitivity of nested-ASP-PCR and ASP-PCR methods. Then, clarithromycin resistance was detected for 99 clinical samples by using different methods, including nested-ASP-PCR, bacterial culture and disk diffusion.

RESULTS: The nested-ASP-PCR method was successfully established to test the resistance mutation points 2142, 2143 and 2144 of the 23SrRNA gene of H. pylori. Among 30 samples of gastric tissue and saliva, the H. pylori detection rate of nested-ASP-PCR was 90% and 83.33%, while the detection rate of ASP-PCR was just 63% and 56.67%. Especially in the saliva samples, nested-ASP-PCR showed much higher sensitivity in H. pylori detection and resistance mutation rates than ASP-PCR. In the 99 RUT-positive gastric tissue and saliva samples, the H. pylori-positive detection rate by nested-ASP-PCR was 87 (87.88%) and 67 (67.68%), in which there were 30 wild-type and 57 mutated strains in gastric tissue and 22 wild-type and 45 mutated strains in saliva. Genotype analysis showed that three-points mixed mutations were quite common, but different resistant strains were present in gastric mucosa and saliva. Compared to the high sensitivity shown by nested-ASP-PCR, the positive detection of bacterial culture with gastric tissue samples was 50 cases, in which only 26 drug-resistant strains were found through analyzing minimum inhibitory zone of clarithromycin.

CONCLUSION: The nested-ASP-PCR assay showed higher detection sensitivity than ASP-PCR and drug sensitivity testing, which could be performed to evaluate clarithromycin resistance of H. pylori.