A Newly Discovered Drug Resistance Gene rfaF In Helicobacter pylori

Molecular Mechanisms of Antibiotic Resistance and Novel Treatment Strategies for Helicobacter pylori Infections

Helicobacter pylori infects approximately 50% of the world's population and is considered the major etiological agent of severe gastric diseases, such as peptic ulcers and gastric carcinoma. Increasing resistance to standard antibiotics has now led to an ever-decreasing efficacy of eradication therapies and the development of novel and improved regimens for treatment is urgently required. Substantial progress has been made over the past few years in the identification of molecular mechanisms which are conducive to resistant phenotypes as well as for efficient strategies to counteract strain resistance and to avoid the use of ineffective antibiotics. These involve molecular testing methods, improved salvage therapies, and the discovery of novel and potent antimicrobial compounds. High rates of prevalence and gastric cancer are currently observed in Asian countries, including Japan, China, Korea, and Taiwan, where concomitantly intensive research efforts were initiated to explore advanced eradication regimens aimed at reducing the risk of gastric cancer. In this review, we present an overview of the known molecular mechanisms of antibiotic resistance and discuss recent intervention strategies for H. pylori diseases, with a view of the research progress in Asian countries.

Role of AlgC and GalU in the Intrinsic Antibiotic Resistance of Helicobacter pylori

Purpose

Helicobacter pylori is associated with the development of gastrointestinal diseases. However, its eradication is challenged by an increased rate of drug resistance. AlgC and GalU are important for the synthesis of UDP-glucose, which is a substrate for the synthesis of lipopolysaccharide (LPS) in H. pylori. In this study, we investigated the role of UDP-glucose in the intrinsic drug resistance in H. pylori.

Methods

Gene knockout strains or complementation strains, including ΔalgC, ΔgalU, ΔgalE, Δhp0045, ΔalgC/algC* and ΔgalU/galU* were constructed in Hp26695; and ΔalgC and ΔgalU were also constructed in two clinical drug-resistant strains, Hp008 and Hp135. The minimum inhibitory concentrations (MIC) of H. pylori to amoxicillin (AMO), tetracycline (TET), clarithromycin (CLA), metronidazole (MNZ), levofloxacin (LEV), and rifampicin (RIF) were measured using MIC Test Strips. Silver staining was performed to examine the role of AlgC and GalU in LPS synthesis. Ethidium bromide (EB) accumulation assay was performed to assess the outer membrane permeability of H. pylori strains.

Results

Knockout of algC and galU in H. pylori resulted in increased drug sensitivity to AMO, MNZ, CLA, LEV, and RIF; whereas knockout of hp0045 and galE, which are involved in GDP-fucose and UDP-galactose synthesis, respectively, did not significantly alter the drug sensitivity of H. pylori. Knockout of algC and galU in clinically drug-resistant strains resulted in significantly increased drug sensitivity to all the antibiotics, except MNZ. The lipid A-core structure was altered in ΔalgC and ΔgalU when their EB accumulation was higher than that in the wild type and complementation strains.

Conclusion

UDP-glucose may play an important role in increasing drug resistance to AMO, MNZ, CLA, LEV, TET, and RIF by maintaining the lipid A-core structure and decreasing membrane permeability. AlgC and GalU may serve as potential drug targets for decreasing antibiotic resistance in clinical isolates.

Biomarker Characterization and Prediction of Virulence and Antibiotic Resistance from Helicobacter pylori Next Generation Sequencing Data

The Gram-negative bacterium Helicobacter pylori colonizes c.a. 50% of human stomachs worldwide and is the major risk factor for gastric adenocarcinoma. Its high genetic variability makes it difficult to identify biomarkers of early stages of infection that can reliably predict its outcome. Moreover, the increasing antibiotic resistance found in H. pylori defies therapy, constituting a major human health problem. Here, we review H. pylori virulence factors and genes involved in antibiotic resistance, as well as the technologies currently used for their detection. Furthermore, we show that next generation sequencing may lead to faster characterization of virulence factors and prediction of the antibiotic resistance profile, thus contributing to personalized treatment and management of H. pylori-associated infections. With this new approach, more and permanent data will be generated at a lower cost, opening the future to new applications for H. pylori biomarker identification and antibiotic resistance prediction.

A randomized, multicenter and noninferiority study of amoxicillin plus berberine vs tetracycline plus furazolidone in quadruple therapy for Helicobacter pylori rescue treatment

OBJECTIVE

Helicobacter pylori (H. pylori) infection is closely associated with gastric ulcers and gastric adenocarcinomas. We aimed to assess the efficacy and safety of a quadruple regimen with amoxicillin plus berberine vs tetracycline plus furazolidone in rescue therapy for H. pylori eradication.

METHODS

We conducted a randomized, open-label, multicenter, noninferiority trial. Patients with previous treatment failures recruited from five centers were randomized (1:1) to receive a regimen with esomeprazole and bismuth plus either berberine and amoxicillin (the BA group) or tetracycline and furazolidone (the TF group) for 14 days. Their H. pylori infection status was confirmed 4-8 weeks after treatment. The primary outcome was the eradication rate. The secondary outcomes included the rates of symptom improvement, compliance, and adverse events. This study was registered at ClinicalTrials.gov (NCT03609892).

RESULTS

Altogether 658 participants were consecutively enrolled. An intention-to-treat analysis demonstrated that the two regimens achieved a similar eradication rate (76.3% vs 77.5%; P = 0.781). The per-protocol analysis reached a similar result (81.5% vs 85.0%; P = 0.278). The eradication rate reached in the BA group was greater than the pre-established margin of noninferiority, at -10% (the lower bounds of the 95% CI were -7.66% and -9.43%, respectively). The rate of adverse events was lower for the BA group than the TF group (18.5% vs 26.1%, P = 0.024). Rates of compliance and symptom improvement were similar for the two therapies.

CONCLUSION

The efficacy of both regimens in rescue treatment for H. pylori eradication was satisfactory, 14-day BA-based quadruple therapy is noninferior to the TF-based therapy.