Genotypic and Phenotypic Resistance to Clarithromycin in Helicobacter pylori Strains

Clarithromycin-resistant Helicobacter pylori in Africa: a systematic review and meta-analysis

BACKGROUND

In 2022, approximately 56.5% of adults and 47.1% of children and adolescents were affected by Helicobacter pylori (H. pylori) infection in Africa, and clarithromycin-resistant H. pylori (CRHp) strains have become global priority pathogens. Therefore, this study aimed to conduct the first comprehensive systematic review and meta-analysis of CRHp in Africa.

METHODS

This investigation was conducted according to the guidelines of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (The PRISMA 2020). Literature search of electronic databases (Google Scholar, African Journals Online, ResearchGate, PubMed, Embase, and Scopus) was performed using keywords "clarithromycin", "Helicobacter pylori", "African country name", "mutation in the 23S rRNA".

RESULTS

Sixty-five studies involving 5,313 H. pylori strains isolated over 26 years (1997-2022) from 23 African countries were included in this study. The samples from which CRHp was isolated included gastric biopsy (60/63; 95%), and stool (4/63; 6%). The pooled prevalence of CRHp in Africa was 27% (95% CI: 22, 33). There was a steady trend in the prevalence of CRHp isolated in Africa over the 26 years (R2 = 0.0001, p = 0.92, slope coefficient of -0.05x). Ten types of 23S rRNA mutations (conferring clarithromycin resistance) were identified, and included mainly A2143G (465 H. pylori strains out of 1178 tested) and A2142G (344 H. pylori strains out of 1027).

CONCLUSION

To enhance the accuracy and validity of surveillance data for H. pylori in Africa, there is an urgent need for implementing standardized microbiological methods for resistance detection. The prevalence of CRHp reported in this study was very similar to the overall global prevalence and there is a need for more representative studies on CRHp in Africa. While waiting for this, the treatment of H. pylori infections must be based on the guidelines of the AHMSG first Lagos consensus.

Declining eradication rates of Helicobacter pylori with standard triple therapy in Addis Ababa, Ethiopia

BACKGROUND

Standard triple therapy is an effective treatment for eradicating Helicobacter pylori infection, but it is encountered with drug resistance. The stool antigen test is a cost-effective and easy-to-perform test to confirm the eradication of H. pylori, 4-8 weeks post-therapy, with 86% sensitivity and 92% specificity.

AIM

To assess the H. pylori eradication rate of standard triple therapy and factors affecting the eradication rate.

METHODS

We conducted a prospective, multicenter follow-up study in Addis Ababa, Ethiopia, at selected healthcare facilities among dyspeptic patients with positive stool H. pylori antigen tests from June 1, 2023 to October 30, 2023 to assess the H. pylori eradication rate. After completing the standard triple therapy, the eradication was confirmed using a stool antigen test 4 weeks later. The data were analyzed using bivariate and multivariate logistic regression methods.

RESULTS

The H. pylori eradication rate was 85.4%. Patients with a previous diagnosis of H. pylori infection, smokers, and local alcohol consumption were associated with a lower H. pylori eradication rate, with adjusted odds ratio (AORs) of 0.159 [95% confidence interval (CI): 0.050-0.511], 0.206 (95%CI: 0.052-0.822), and 0.228 (95%CI: 0.052-0.997), respectively. Patients with complete symptom resolution were 5.383 times more likely to achieve eradication than patients without symptom improvement, AOR = 5.383, 95%CI: 1.74-21.089.

CONCLUSION

H. pylori eradication rate was lower than expected. Post-treatment testing is crucial to confirm eradication and guide further management, such as susceptibility testing.

Helicobacter pylori resistance in Hainan Province, China: investigating phenotypes and genotypes through whole-genome sequencing

Helicobacter pylori is increasingly resistant to antibiotics, significantly lowering eradication rates and posing a major public health challenge. This study investigated the distribution of antibiotic-resistant phenotypes and genotypes of H. pylori in Hainan Province. It determined the minimum inhibitory concentrations (MICs) of six antibiotics using the E-test method and detected resistance genes via Sanger sequencing. Furthermore, we compared resistance detection based on phenotypic analysis and whole genome sequencing (WGS) across 19 clinical isolates of H. pylori. A total of 140 H. pylori strains were isolated. The resistance rates to levofloxacin (LEV), clarithromycin (CLA), and metronidazole (MTZ) were 37.9%, 40.0%, and 93.6%, respectively. Notably, only 3.3% of the strains were susceptible to all six antibiotics. Multidrug-resistant strains accounted for 25.0% of the total, with no resistance detected to amoxicillin (AMX), tetracycline (TET), or furazolidone (FR) during the study period. Genotypic resistance to CLA and LEV showed near-perfect concordance with phenotypic resistance, with Kappa values of 0.910 and 0.938, respectively. Although all isolates were phenotypically sensitive to TET, 16 exhibited a mutation in the 16S rRNA gene (A926G). All strains harboring the R16H/C mutation and truncated rdxA were resistant to metronidazole, demonstrating a specificity of 100%. Therefore, FR, AMX, and TET are recommended as suitable empirical treatment options for H. pylori infections in this region. Genotypic analysis provides a reliable method for predicting resistance to CLA and LEV. WGS proves to be a valuable tool for identifying novel resistance loci in H. pylori and contributes to the phylogenetic classification of strains.

Genetic Determinants of Clarithromycin and Fluoroquinolones Resistance in Helicobacter pylori in Serbia

BACKGROUND/OBJECTIVES

Stomach infections by Helicobacter pylori can cause acute or chronic gastritis, peptic ulcers, and gastric cancer. The rise in antibiotic resistance is a significant health issue highlighted by the World Health Organization. The increasing number of treatment failures underscores the necessity for antibiotic susceptibility testing (AST). The study aimed to investigate the current prevalence and resistance to fluoroquinolones and clarithromycin with their detected mutations.

METHODS

Stomach biopsies from symptomatic patients were subjected to molecular testing by GenoType Helico DR kit (Hain Lifescience GmbH, Nehren, Germany).

RESULTS

Positive findings on the presence of H. pylori were detected in 42.4% of symptomatic patients, with the significant majority of patients (69%) having previously failed treatments. The resistance rates to fluoroquinolones and clarithromycin were 53.9% and 58.5%, respectively, with significantly higher rates in secondary resistant strains. The main resistance markers in fluoroquinolones and clarithromycin were N87K (27.4%) and A2147G (78.6%), respectively. Hetero-resistance or mixed genotypes were detected in over 20% of tested patients. During the study period, a significant increase in trends in both fluoroquinolones and clarithromycin resistance rates was observed.

CONCLUSIONS

Results indicate the need for the implementation of the latest Maastricht VI Consensus recommendations for both AST whenever possible and the use of tailored guided therapy options due to high resistance rates and possible treatment failures. The GenoType Helico DR kit is a useful tool for AST, especially in cases of mixed H. pylori genotypes.

Culture-based susceptibility-guided tailored versus empirical concomitant therapy as first-line Helicobacter pylori treatment: A randomized clinical trial

BACKGROUND

With the increasing resistance to antimicrobial agents, susceptibility-guided tailored therapy has been emerging as an ideal strategy for Helicobacter pylori treatment. However, susceptibility-guided tailored therapy requires additional cost, time consumption, and invasive procedure (endoscopy) and its superiority over empirical quadruple therapy as the first-line H. pylori treatment remains unclear.

AIMS

To compare the efficacy of culture-based susceptibility-guided tailored versus empirical concomitant therapy as the first-line Helicobacter pylori treatment.

METHODS

This open-label, randomized trial was performed in four Korean institutions. A total of 312 Patients with H. pylori-positive culture test and naïve to treatment were randomly assigned in a 3:1 ratio to either culture-based susceptibility-guided tailored therapy (clarithromycin-based or metronidazole-based triple therapy for susceptible strains or bismuth quadruple therapy for dual-resistant strains, n = 234) or empirical concomitant therapy (n = 78) for 10 days. Eradication success was evaluated by 13C-urea breath test at least 4 weeks after treatment.

RESULTS

Prevalence of dual resistance to both clarithromycin and metronidazole was 8%. H. pylori eradication rates for tailored and concomitant groups were 84.2% and 83.3% by intention-to-treat analysis (p = 0.859), respectively, and 92.9% and 91.5% by per-protocol analysis, respectively (p = 0.702), which were comparable between the two groups. However, eradication rates for dual-resistant strains were significantly higher in the tailored group than in the concomitant group. All adverse events were grade 1 or 2 based on the Common Terminology Criteria for Adverse Events and the incidence was significantly lower in the tailored group. The proportion of patients discontinuing treatment for adverse events was comparable between the two groups (2.1% vs. 2.6%).

CONCLUSIONS

The culture-based susceptibility-guided tailored therapy failed to show superiority over the empirical concomitant therapy in terms of eradication rate. Based on these findings, the treatment choice in clinical practice would depend on the background rate of antimicrobial resistance, availability of resources and costs associated with culture and susceptibility testing.

Role of MIC levels and 23S rRNA mutation sites to clarithromycin in 14-day clarithromycin bismuth quadruple therapy for Helicobacter pylori eradication: A prospective trial in Beijing

Background

Rising clarithromycin resistance undermines Helicobacter pylori (H. pylori) treatment efficacy. We aimed to determine clarithromycin's minimum inhibitory concentration (MIC) levels and identify specific mutation sites in the 23S ribosomal subunit (23S rRNA) that predict treatment outcomes in a 14-day regimen of clarithromycin bismuth quadruple therapy (amoxicillin 1g, clarithromycin 500 mg, rabeprazole 10 mg, and colloidal bismuth pectin 200 mg).

Materials and methods

We included adult H. pylori patients who hadn't previously undergone clarithromycin-based treatment, either as initial or rescue therapy. Exclusions were made for penicillin allergy, recent use of related medications, severe illnesses, or inability to cooperate. Patients underwent a 14-day clarithromycin bismuth quadruple therapy. Gastric mucosa specimens were obtained during endoscopy before eradication. MIC against amoxicillin and clarithromycin was determined using the E-test method. The receiver operating characteristic (ROC) curve helped to find the optimal clarithromycin resistance MIC breakpoint. Genetic sequences of H. pylori 23S rRNA were identified through Sanger Sequencing. (ChiCTR2200061476).

Results

Out of 196 patients recruited, 92 met the inclusion criteria for the per-protocol (PP) population. The overall intention-to-treat (ITT) eradication rate was 80.00 % (84/105), while the modified intention-to-treat (MITT) and PP eradication rates were 90.32 % (84/93) and 91.30 % (84/92) respectively. No amoxicillin resistance was observed, but clarithromycin resistance rates were 36.19 % (38/105), 35.48 % (33/93), and 34.78 % (33/92) in the ITT, MITT, and PP populations respectively. Compared with the traditional clarithromycin resistance breakpoint of 0.25 μg/mL, a MIC threshold of 12 μg/mL predicted better eradication. Among 173 mutations on 152 sites in the 23S rRNA gene, only the 2143A > G mutation could predict eradication outcomes (p < 0.000).

Conclusions

Interpretation of elevated MIC values is crucial in susceptibility testing, rather than a binary "susceptible" or "resistant" classification. The 2143A > G mutation has limited specificity in predicting eradication outcomes, necessitating further investigation into additional mutation sites associated with clarithromycin resistance.

Antibiotic Resistance of Helicobacter pylori: Mechanisms and Clinical Implications

Helicobacter pylori is a pathogenic bacterium associated with various gastrointestinal diseases, including chronic gastritis, peptic ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. The increasing rates of H. pylori antibiotic resistance and the emergence of multidrug-resistant strains pose significant challenges to its treatment. This comprehensive review explores the mechanisms underlying the resistance of H. pylori to commonly used antibiotics and the clinical implications of antibiotic resistance. Additionally, potential strategies for overcoming antibiotic resistance are discussed. These approaches aim to improve the treatment outcomes of H. pylori infections while minimizing the development of antibiotic resistance. The continuous evolution of treatment perspectives and ongoing research in this field are crucial for effectively combating this challenging infection.

Prevalence of Clarithromycin-Resistant Helicobacter pylori Strains in Zambia: A Sub-Saharan African Country

INTRODUCTION

Helicobacter pylori (H. pylori) is one of the most important infections globally, affecting more than 50% of the human population. Clarithromycin (CLA)-containing regimens are recommended for empirical eradication of H. pylori in populations with less than 15% resistance. The aim of this study was to estimate the prevalence of CLA resistance in samples collected from Zambian patients to determine if CLA is suitable for first-line H. pylori empirical treatment.

METHODOLOGY

We used archival biopsy samples collected from dyspeptic patients undergoing endoscopy. The samples had been snap-frozen immediately after collection and stored at -80°C. We performed multiplex real-time PCR using Bosphore Helicobacter pylori Genotyping Kits v1, Istanbul, Turkey, to determine the presence of wild-type H. pylori and three mutations, A2142G, A2142C, and A2143G, of domain V in 23s rRNA gene.

RESULTS

We tested 259 gastric biopsy samples from patients with dyspepsia, of which 136 (53%) were from females. The median age was 48 years (IQR 40-61 years). Endoscopically, most of the patients, 164 (63%), had a normal gastric mucosa. CLA resistance was found in 48 (28%) samples, with A2142G mutation in 23 (13%), A2143G mutation in 32 (18%), and double mutations A2142C and A2143G in 6 (3%).

CONCLUSIONS

The presence of significant levels of CLA resistance in Zambia suggests that it should not be used as first-line empirical treatment for H. pylori infection. However, with a limitation of suitable alternatives, there is an urgent need to formulate new treatment approaches.

Comparison of the Efficacy of Two-Week Vonoprazan Versus Lansoprazole-Based Quadruple Sequential Antibiotic Therapy in Eradicating Helicobacter pylori Infection: A Non-randomized Clinical Trial

AIM

The prevalence of Helicobacter pylori is escalating in developing countries, exacerbated by unjustified antibiotic usage, which leads to increased resistance. This trend has been notably amplified since the COVID-19 pandemic. Consequently, the effectiveness of existing eradication regimens has been compromised. This study aimed to compare the efficacy of two weeks of vonoprazan-based quadruple sequential therapy and lansoprazole-based quadruple sequential therapy in treating H. pylori infection.  Methods: A non-randomized clinical trial was conducted over 18 months at the Department of Gastroenterology, Lahore General Hospital, Lahore, Pakistan. It included patients presenting with dyspepsia, as defined by the Rome IV criteria, and who tested positive on the urea breath test. Patients were divided into two groups, i.e., Group A and Group B. Group A patients received lansoprazole 30 mg + amoxicillin + tinidazole + tab. colloidal bismuth subcitrate for the first seven days, followed by lansoprazole + levofloxacin + azithromycin + colloidal bismuth subcitrate. Group B patients received vonoprazan + amoxicillin + tinidazole + colloidal bismuth subcitrate for the first seven days, followed by vonoprazan + levofloxacin + azithromycin + colloidal bismuth subcitrate. Both regimes continued for 14 days. Four weeks after 14 days of the treatment, an early morning urea breath test was conducted to evaluate the efficacy of the treatment. Patients were scheduled for follow-up visits at seven and 14 days post-treatment initiation to record adverse events and assess compliance with the treatment regimen. Patients who lost the follow-up and remained non-compliant to the medications were excluded from the final data analysis as per standard protocols of the per-protocol analysis.  Results: A total of 252 patients were included. In Group A and Group B, 6/126 (4.76%) and 8/126 (6.35%) of the patients were lost to follow-up, respectively. The non-compliance rate in Group A was 5/126 (3.97%), compared to Group B with 3/126 (2.38%). Finally, the per-protocol analysis of the results included 115 patients in each group. Baseline characteristics, including demographics, lifestyle, and clinical factors, were comparable between groups with p-values of 0.138 for age, 0.356 for gender, 0.126 for BMI, 0.495 for residence, 0.500 for water source, 0.866 for meal habit, 0.863 for smoking, 0.188 for nonsteroidal anti-inflammatory drug (NSAID) use, 0.145 for proton pump inhibitor (PPI) use, 0.213 for antibiotics, and 0.456 for treatment history. Both treatments effectively eradicated H. pylori, as determined by a negative urea breath test at four weeks post-treatment, with Group B showing a higher eradication rate of 96.5% compared to 92.2% in Group A, although the difference was not statistically significant (p = 0.153). There was no difference in adverse effects in both treatment groups (p-value > 0.05).  Conclusion: The study found that while the vonoprazan-based regime exhibited a slightly higher eradication rate of H. pylori compared to lansoprazole, the difference was not statistically significant. It was concluded that both regimens demonstrated comparable efficacy and similar profiles of adverse effects in treating H. pylori infection.

Whole genome sequencing reveals novel genetic mutations of Helicobacter pylori associating with resistance to clarithromycin and levofloxacin

BACKGROUND

Detection of mutations in one or a couple of genes may not provide enough data or cover all the genomic DNA variance related to antibiotic resistance of Helicobacter pylori to clarithromycin (CLA) and levofloxacin (LVX). We aimed to perform whole genome sequencing to explore novel antibiotic resistance-related genes to increase predictive accuracy for future targeted sequencing tests.

METHODS

Gastric mucosal biopsies were taken during upper endoscopy in 27 H. pylori-infected patients. According to culture-based antibacterial susceptibility test, H. pylori strains were divided into three groups, with nine strains in each group: CLA single-drug resistance (group C), LVX single-drug resistance (group L), and strains sensitive to all antibacterial drugs (group S). Based on whole genome sequencing with group S being the control, group C and group L group-specific single nucleotide variants and amino acid mutations were screened, and potential candidate genes related to CLA and LVX resistance were identified.

RESULTS

The median age of study subjects was 35 years (IQR: 31-40), and 17 (63.0%) were male. All nine CLA-resistant strains had A2143G mutations in 23S rRNA, while none of nine sensitive strains had the mutation. Six of nine strains in group L and six of nine strains in group S had 87th or 91st mutation in gyrA. After comparing sequencing data of strains among the three groups, we identified five mutated positions belonging to four genes related to CLA resistance, and 31 mutated positions belonging to 20 genes related to LVX resistance. Novel genetic mutations were detected for CLA resistance (including fliJ and clpX) and LVX resistance (including fliJ, cheA, hemE, Val360Ile, and HP0568). Missense mutations in fliJ and cheA gene were mainly involved in chemotaxis and flagellar motility to facilitate bacterial escape of antibiotics, while the functions of other novel gene mutations underpinning antibiotic resistance remain to be investigated.

CONCLUSION

Whole genome sequencing detected potential novel genetic mutations conferring resistance of H. pylori to CLA and LVX including fliJ and cheA. Further studies to correlate these findings with treatment outcome should be performed.

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.

A Survey of Helicobacter pylori Antibiotic-Resistant Genotypes and Strain Lineages by Whole-Genome Sequencing in China

Antibiotic resistance is the most important factor leading to failed Helicobacter pylori eradication therapy, and personalized treatment based on antibiotic susceptibility is becoming increasingly important. To strengthen the understanding of antibiotic genotypic resistance of H. pylori and identify new antibiotic resistance loci, in this study, we identified phenotypic resistance information for 60 clinical isolates and compared the concordance of phenotypic and genotypic resistance using whole-genome sequencing (WGS). Clarithromycin and levofloxacin genotypic resistance was in almost perfect concordance with phenotypic resistance, with kappa coefficients of 0.867 and 0.833, respectively. All strains with the R16H/C mutation and truncation in rdxA were metronidazole resistant, with 100% specificity. For other genes of concern, at least one phenotypically sensitive strain had a previous mutation related to antibiotic resistance. Moreover, we found that the A1378G mutation of HP0399 and the A149G mutation of FabH might contribute to tetracycline resistance and multidrug resistance, respectively. Overall, the inference of resistance to clarithromycin and levofloxacin from genotypic resistance is reliable, and WGS has been very helpful in discovering novel H. pylori resistance loci. In addition, WGS has also enhanced our study of strain lineages, providing new ways to understand resistance information and mechanisms.

Effect and Safety of Helicobacter pylori Eradication Treatment Based on Molecular Pathologic Antibiotic Resistance in Chinese Elderly People

Background

The elderly people generally have poor tolerance to drugs and an increased risk of adverse effects. Our study was designed to determine the effect and safety of Helicobacter pylori (H. pylori) eradication treatment based on molecular pathologic antibiotic resistance in Chinese elderly people over the age of 60 years.

Methods

A total of 364 people were retrospectively analyzed, including 113 older people over 60 and 251 young and middle-aged people in the age of 20–59 years. Real-time PCR detection and conventional PCR and sequencing method were used for drug susceptibility testing. As the main outcome measure, the eradication rates (ERs) with their 95% confidence intervals (CIs) were analyzed by intention to treat (ITT) and per protocol (PP). For the safety of therapy, adverse events were analyzed.

Results

For the total people, the resistance rates to clarithromycin (CLR), amoxicillin (AMX), fluoroquinolone (FLQ) and tetracycline (TET) were 65.06%, 7.54%, 61.39% and 20.37%, respectively. After they were divided into two groups, the resistance rates were 62.39% (CLR), 9.09% (AMX), 69.64% (FLQ) and 22.45% (TET) in the 113 older people over 60, and 66.26%, 6.85%, 57.66% and 19.47% in the 251 young and middle-aged people in 20–59. By the ITT analysis, the ERs were 92.04% (95% CI, 86.97–97.10%, n=113) in the older people and 92.43% (95% CI, 89.14–95.73%, n=251) in the young and middle-aged people. By the PP analysis, the ERs were 96.30% (95% CI, 92.68–99.92%, n=108) and 94.69% (95% CI, 91.87–97.52%, n=245), respectively. No significant differences were shown both in the ITT analysis (P=0.896) and in the PP analysis (P=0.517). The three most common adverse events were black stool, dysgeusia and diarrhea, and no serious adverse event was reported.

Conclusion

H. pylori eradication treatment based on molecular pathologic antibiotic resistance showed good effect and safety in Chinese elderly people.

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.

Efficacy of Phenotype-vs. Genotype-Guided Therapy Based on Clarithromycin Resistance for Helicobacter pylori Infection in Children

BACKGROUND

Clarithromycin resistance reduces the eradication rate of Helicobacter pylori (H. pylori). Cultures with susceptibility testing and molecular determination of genotypes are recommended to guide-tailored therapy.

METHODS

We retrospectively enrolled patients aged 6 and 18 years with H. pylori infection, who underwent an endoscopy and agreed to undergo both culture and genetic testing for clarithromycin resistance. Patients receiving tailored therapy based on traditional culture results (phenotype-guided therapy) or genetic testing results (genotype-guided therapy) were included in the study. ¹³C-urea breath test was used to evaluate the success of eradication at least 4 weeks after the completion of treatment. We aimed to determine whether the eradication rate of phenotype- or genotype-guided therapy based on clarithromycin resistance is greater than 90% in children.

RESULTS

Between September 2017 and October 2020, 226 eligible patients were enrolled. There were 71 with clarithromycin-sensitive strains in the phenotype-guided therapy group and 87 without 23S rRNA point mutations (A2142G, A2142C, and A2143G) in the genotype-guided therapy group. Eradication rates were 70.4% (50/71, [95% CI: 58.4-80.7%] for phenotype-guided therapy and 92.0% (80/87, [95% CI: 84.1-96.7%]) for genotype-guided therapy (P < 0.01). The incidence of side effects was 4.2% (3/71) and 10.3% (9/87), with no major differences between these two groups (P = 0.15), respectively. The compliance rate was also similar (97.2 vs. 95.4%, P = 0.87).

CONCLUSION

Tailored therapy according to genetic testing results achieved eradication rates of 92% and was superior to tailored therapy guided by traditional culture results.

Clinical Relevance of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is a Gram-negative helical, microaerophilic bacterium which colonizes the antrum and body of the stomach, surviving in its harsh environment through mechanisms of acid resistance and colonization factors. It infects approximately 50% of the world population. Although the prevalence of this infection varies from country to country, as well as between different ethnic, social or age groups, it is estimated that about 50% of the human population only carries this microorganism. While H. pylori has been found to play a major etiological and pathogenic role in chronic gastritis, peptic ulcer disease and gastric cancer, its importance for many types of extra-gastric disease needs to be further investigated. The choice of tests to diagnose H. pylori infection, defined as invasive or non-invasive, depends on the clinical indication as to whether to perform upper gastrointestinal endoscopy. Focusing on bacterial eradication, the treatment should be decided locally based on the use of antibiotics and documented antibiotic resistance. The author provides an overview of the current state of knowledge about the clinical aspects of H. pylori infection, especially its diagnostic and therapeutic management.

Next Generation Sequencing for the Prediction of the Antibiotic Resistance in Helicobacter pylori: A Literature Review

Background and aims: Only a few antimicrobials are effective against H. pylori, and antibiotic resistance is an increasing problem for eradication therapies. In 2017, the World Health Organization categorized clarithromycin resistant H. pylori as a "high-priority" bacterium. Standard antimicrobial susceptibility testing can be used to prescribe appropriate therapies but is currently recommended only after the second therapeutic failure. H. pylori is, in fact, a "fastidious" microorganism; culture methods are time-consuming and technically challenging. The advent of molecular biology techniques has enabled the identification of molecular mechanisms underlying the observed phenotypic resistance to antibiotics in H. pylori. The aim of this literature review is to summarize the results of original articles published in the last ten years, regarding the use of Next Generation Sequencing, in particular of the whole genome, to predict the antibiotic resistance in H. pylori.Methods: a literature research was made on PubMed. The research was focused on II and III generation sequencing of the whole H. pylori genome. Results: Next Generation Sequencing enabled the detection of novel, rare and complex resistance mechanisms. The prediction of resistance to clarithromycin, levofloxacin and amoxicillin is accurate; for other antimicrobials, such as metronidazole, rifabutin and tetracycline, potential genetic determinants of the resistant status need further investigation.

Phenotypic and Genotypic Antibiotic Resistance Patterns in Helicobacter pylori Strains From Ethnically Diverse Population in México

Helicobacter pylori strains carry a range of mutations in genes that confer antimicrobial resistance and restrict the available options to treat the infection. Latin America is a region that conserve a large number of indigenous communities relatively isolated that practice a traditional medicine without consumption of drugs. We hypothesized that rates of antibiotic resistance are lower in these communities. Recent progress in whole-genome sequencing has allowed the study of drug susceptibility by searching for the known mutations associated with antibiotic resistance. The aim of this work was to study trends of antibiotic resistance over a 20-year period in Mexican H. pylori strains and to compare susceptibility between strains from Mexican mestizos and from indigenous population; we also aimed to learn the prevalence of mutational patterns in genes gyrA, gyrB, rdxA, frxA, rpsU, omp11, dppA, and 23S rRNA and its association with phenotypic tests. Resistance to clarithromycin, metronidazole, amoxicillin and levofloxacin was determined in167 H. pylori isolates by E-test, and the occurrence of mutational patterns in specific genes was determined by whole genome sequencing (WGS). The trend of resistance over 20 years in mestizo isolates showed significant resistant increase for clarithromycin and levofloxacin to frequencies that banned its clinical use. Resistance in H. pylori isolates of native communities was lower for all antibiotics tested. Phenotypic resistance showed good to moderate correlation with genotypic tests. Genetic methods for characterizing antibiotic resistance require further validation in each population.