A systematic review and meta-analysis of genotypic methods for detecting antibiotic resistance in Helicobacter pylori

Change in Diagnosis of Helicobacter pylori Infection in the Treatment-Failure Era

Helicobacter pylori (H. pylori) infection is a prevalent global health issue, associated with several gastrointestinal disorders, including gastritis, peptic ulcers, and gastric cancer. The landscape of H. pylori treatment has evolved over the years, with increasing challenges due to antibiotic resistance and treatment failure. Traditional diagnostic methods, such as the urea breath test, stool antigen test, and endoscopy with biopsy, are commonly used in clinical practice. However, the emergence of antibiotic-resistant strains has led to a decline in treatment efficacy, necessitating a re-evaluation of common diagnostic tools. This narrative review aims to explore the possible changes in the diagnostic approach of H. pylori infection in the era of treatment failure. Molecular techniques, including polymerase chain reaction and whole genome sequencing, which have high sensitivity and specificity, allow the detection of genes associated with antibiotic resistance. On the other hand, culture isolation and a phenotypic antibiogram could be used in the diagnostic routine, although H. pylori is a fastidious bacterium. However, new molecular approaches are promising tools for detecting the pathogen and its resistance genes. In this regard, more real-life studies are needed to reveal new diagnostic tools suitable for identifying multidrug-resistant H. pylori strains and for outlining proper treatment.

Testing for Helicobacter pylori in an era of antimicrobial resistance

Antimicrobial resistance in Helicobacter pylori has reached alarming levels and is compromising traditional empiric treatment of H. pylori. Antimicrobial susceptibility testing is routinely performed for infectious diseases when there is a risk of resistance and is now recommended to guide therapy for H. pylori. This mini-review overviews the current diagnostics for H. pylori with a focus on tests that enable susceptibility-guided treatment, including molecular tests performed directly on stool and endoscopically collected specimens.

Success of susceptibility-guided eradication of Helicobacter pylori in a region with high secondary clarithromycin and levofloxacin resistance rates

BACKGROUND

Resistance to clarithromycin (CLA) and levofloxacin (LFX) of Helicobacter pylori (H. pylori) is increasing in severity, and successful eradication is essential. Presently, the eradication success rate has greatly declined, leaving a large number of patients with previous treatment histories.

AIM

To investigate secondary resistance rates, explore risk factors for antibiotic resistance, and assess the efficacy of susceptibility-guided therapy.

METHODS

We recruited 154 subjects positive for Urea Breath Test who attended The First Affiliated Hospital of China Medical University between July 2022 and April 2023. Participants underwent a string test after an overnight fast. The gastric juice was obtained and transferred to vials containing storage solution. Subsequently, DNA extraction and the specific DNA amplification were performed using quantitative polymerase chain reaction (qPCR). Demographic information was also analyzed as part of the study. Based on these results, the participants were administered susceptibility-guided treatment. Efficacy was compared with that of the empiric treatment group.

RESULTS

A total of 132 individuals tested positive for the H. pylori ureA gene by qPCR technique. CLA resistance rate reached a high level of 82.6% (n = 109), LFX resistance rate was 69.7% (n = 92) and dual resistance was 62.1% (n = 82). Gastric symptoms [odds ratio (OR) = 2.782; 95% confidence interval (95%CI): 1.076-7.194; P = 0.035] and rural residence (OR = 5.152; 95%CI: 1.407-18.861; P = 0.013) were independent risk factors for secondary resistance to CLA and LFX, respectively. A total of 102 and 100 individuals received susceptibility-guided therapies and empiric treatment, respectively. The antibiotic susceptibility-guided treatment and empiric treatment groups achieved successful eradication rates of 75.5% (77/102) and 59.0% (59/411) by the intention-to-treat (ITT) analysis and 90.6% (77/85) and 70.2% (59/84) by the per-protocol (PP) analysis, respectively. The eradication rates of these two treatment strategies were significantly different in both ITT (P = 0.001) and PP (P = 0.012) analyses.

CONCLUSION

H. pylori presented high secondary resistance rates to CLA and LFX. For patients with previous treatment failures, treatments should be guided by antibiotic susceptibility tests or regional antibiotic resistance profile.

Tailored therapy guided by genotypic resistance of clarithromycin and levofloxacin detected by polymerase chain reaction in the first-line treatment of Helicobacter pylori infection

OBJECTIVES

We aimed to explore the efficacy and safety of tailored therapy guided by genotypic resistance in the first-line treatment of Helicobacter pylori (H. pylori) infection in treatment-naive patients.

METHODS

Gastric mucosal specimens were taken during gastroscopy, and main mutations of clarithromycin- and levofloxacin-resistant genes were detected by polymerase chain reaction (PCR). Sensitive antibiotics were selected individually for treating H. pylori infection with tailored bismuth-containing quadruple therapy (BQT) consisting of esomeprazole 20 mg twice daily, bismuth potassium citrate 220 mg twice daily, amoxicillin 1 g twice daily, and clarithromycin 500 mg twice daily, or levofloxacin 500 mg once daily, or metronidazole 400 mg four times daily. Safety and patient compliance were assessed 1-3 days after eradication. Treatment outcome was evaluated by urea breath test 4-8 weeks after eradication.

RESULTS

One hundred and thirty-two treatment-naive patients with H. pylori infection were included. PCR results suggested resistance rates of 47.7% and 34.9% for clarithromycin and levofloxacin, respectively, and a dual resistance rate of 18.2%. Eradication rates of tailored BQT were 87.1% and 95.8% by intention-to-treat (ITT) analysis and per-protocol (PP) analysis, respectively. There was no statistically significant difference in the efficacy of 7-day clarithromycin-containing, 7-day levofloxacin-containing, and 14-day full-dose metronidazole-containing BQT (ITT analysis: P = 0.488; PP analysis: P = 0.833). The incidence of adverse events was 19.7%, and patient compliance was 97.7%.

CONCLUSION

Tailored BQT guided by genotypic resistance can achieve satisfactory efficacy, safety, and patient compliance in the first-line treatment of H. pylori infection.

Efficacy of genotypic susceptibility-guided tailored therapy for Helicobacter pylori infection: A systematic review and single arm meta-analysis

BACKGROUND AND AIM

The prevalence of antibiotic resistance for Helicobacter pylori (H. pylori) has been increasing over the year, making it more difficult for traditional empirical therapy to successfully eradicate H. pylori. Thus, tailored therapy (TT) guided by molecular-based antibiotic susceptibility testing (AST) has been frequently recommended. We conducted a single-arm meta-analysis to determine the efficacy of tailored therapy guided by molecular-based AST.

METHODS

A systematic literature review was performed on multiple databases, and studies on molecular-based TT were included. The eradication rates of TT by intention-to-treat (ITT) and per-protocol (PP) analyses were pooled respectively.

RESULTS

A total of 35 studies from 31 literature (4626 patients) were included in the single-arm meta-analysis. Overall, the pooled eradication rate of TT was 86.9% (95% CI:84.7%-89.1%) by the ITT analysis, and 91.5% (95% CI:89.8%-93.2%) by PP analysis. The pooled eradication rates of first-line TT and rescue TT were 86.6% and 85.1% by ITT analysis and 92.0% and 87.9% by PP analysis, respectively. When tailored rescue therapy was based on the genotypic resistance to at least four antibiotics, the pooled eradication rates reached 89.4% by ITT analysis and 92.1% by PP analysis. For genotype-susceptive strains, the pooled eradication rate of TT with targeted antibiotics was 93.1% (95% CI:91.3%-94.9%), among which the pooled eradication rate of tailored bismuth quadruple therapy was the highest (94.3%). Besides, the eradication rate of 7-day TT or tailored triple therapy without bismuth for genotype-susceptive strains could both reach more than 93.0%.

CONCLUSION

Tailored therapy guided by molecular-based AST can achieve somewhat ideal therapeutic outcomes. TT with a 7-day duration or without bismuth for genotype-susceptible strains can achieve good eradication efficacy. The effectiveness of TT can be improved to some extent by expanding the coverage of AST or by adding bismuth.

Drug-Resistant Helicobacter pylori: Diagnosis and Evidence-Based Approach

Helicobacter pylori (H. pylori) is the most common chronic bacterial infection, affecting approximately half of the world's population. H. pylori is a Class I carcinogen according to the World Health Organization, and the International Agency for Research on Cancer (IARC) has linked it to 90% of stomach cancer cases worldwide. The overall pattern points to a yearly reduction in eradication rates of H. pylori with the likelihood of success further decreasing after each unsuccessful therapeutic effort. Antimicrobial resistance in Helicobacter pylori is a major public health concern and is a predominant cause attributed to eradication failure. As a result, determining H. pylori's antibiotic susceptibility prior to the administration of eradication regimens becomes increasingly critical. Detecting H. pylori and its antimicrobial resistance has traditionally been accomplished by time-consuming culture and phenotypic drug susceptibility testing. The resistance of H. pylori to different antibiotics is caused by various molecular mechanisms, and advances in sequencing technology have greatly facilitated the testing of antibiotic susceptibility to H. pylori. This review will summarize H. pylori antibiotic resistance patterns, mechanisms, and clinical implications. We will also review the pros and cons of current antibiotic susceptibility testing methods. Along with a comparison of tailored susceptibility-guided regimens and empirical therapy based on the latest evidence, an evidence-based approach to such situations will be explored.

Molecular testing-guided therapy versus susceptibility testing-guided therapy in first-line and third-line Helicobacter pylori eradication: two multicentre, open-label, randomised controlled, non-inferiority trials

BACKGROUND

Helicobacter pylori infection is an important causal factor of gastric cancer and peptic ulcer disease and is associated with immune thrombocytopenic purpura and functional dyspepsia. In H pylori strains, point mutations in the 23S rRNA and gyrA genes are associated with clarithromycin resistance and levofloxacin resistance, respectively. Whether the efficacy of molecular testing-guided therapy is non-inferior to that of susceptibility testing-guided therapy for H pylori eradication is unclear. Therefore, we aimed to compare the efficacy and safety of molecular testing-guided therapy and traditional culture-based susceptibility testing-guided therapy in first-line and third-line treatment of H pylori infection.

METHODS

We did two multicentre, open-label randomised trials in Taiwan. In trial 1 (done at seven hospitals), treatment-naive individuals infected with H pylori who were aged 20 years or older were eligible for study inclusion. In trial 2 (done at six hospitals), individuals aged 20 years or older who failed treatment after two or more eradication therapies for H pylori infection were eligible for enrolment. Eligible patients were randomly assigned (1:1) to receive either molecular testing-guided therapy or susceptibility testing-guided therapy. The randomisation sequence was generated by computer using permuted block randomisation with a block size of 4. All investigators were masked to the randomisation sequence. Clarithromycin and levofloxacin resistance were determined by agar dilution test for measuring minimum inhibitory concentrations in the susceptibility testing-guided therapy group, and by PCR and direct sequencing for detection of 23S rRNA and gyrA mutations in the molecular testing-guided therapy group. Study participants received clarithromycin sequential therapy, levofloxacin sequential therapy, or bismuth quadruple therapy according to the resistance status to clarithromycin and levofloxacin. The 13C-urease breath test was used to determine the status of H pylori infection at least 6 weeks after eradication therapy. The primary outcome was the eradication rate by intention-to-treat analysis. The frequency of adverse effects was analysed in patients with available data. The prespecified margins for non-inferiority were 5% for trial 1 and 10% for trial 2. The trials are ongoing for post-eradication follow-up and registered with ClinicalTrials.gov, NCT03556254 for trial 1, and NCT03555526 for trial 2.

FINDINGS

Between March 28, 2018, and April 23, 2021, 560 eligible treatment-naive patients with H pylori infection were recruited and randomly assigned to the molecular testing-guided therapy group or the susceptibility testing-guided therapy group in trial 1. Between Dec 28, 2017, and Oct 27, 2020, 320 eligible patients with refractory H pylori infection were recruited and randomly assigned to the molecular testing-guided therapy group or the susceptibility testing-guided therapy group in trial 2. 272 men and 288 women were recruited for trial 1, and 98 men and 222 women were recruited for trial 2. In first-line H pylori treatment, infection was eradicated in 241 (86%, 95% CI 82-90) of 280 patients in the molecular testing-guided therapy group and 243 (87%, 83-91) of 280 patients in the susceptibility testing-guided therapy group by intention-to-treat analysis (p=0·81). In third-line H pylori treatment, infection was eradicated in 141 (88%, 83-93) of 160 patients in the molecular testing-guided therapy group and 139 (87%, 82-92) of 160 patients in the susceptibility testing-guided therapy group by intention-to-treat analysis (p=0·74). The difference in the eradication rate between the molecular testing-guided therapy group and the susceptibility testing-guided therapy group was -0·7% (95% CI -6·4 to 5·0; non-inferiority p=0·071) in trial 1 and 1·3% (-6·0 to 8·5; non-inferiority p=0·0018 in trial 2 by intention-to-treat analysis. We found no difference in adverse effects across both treatment groups in trial 1 and trial 2.

INTERPRETATION

Molecular testing-guided therapy was similar to susceptibility testing-guided therapy in first-line therapy and non-inferior to susceptibility testing guided therapy in third-line treatment of H pylori infection, supporting the use of molecular testing-guided therapy for H pylori eradication.

FUNDING

Ministry of Science and Technology of Taiwan, and Centre of Precision Medicine of the Higher Education Sprout Project by the Ministry of Education of Taiwan.

Helicobacter pylori infection

Helicobacter pylori infection causes chronic gastritis, which can progress to severe gastroduodenal pathologies, including peptic ulcer, gastric cancer and gastric mucosa-associated lymphoid tissue lymphoma. H. pylori is usually transmitted in childhood and persists for life if untreated. The infection affects around half of the population in the world but prevalence varies according to location and sanitation standards. H. pylori has unique properties to colonize gastric epithelium in an acidic environment. The pathophysiology of H. pylori infection is dependent on complex bacterial virulence mechanisms and their interaction with the host immune system and environmental factors, resulting in distinct gastritis phenotypes that determine possible progression to different gastroduodenal pathologies. The causative role of H. pylori infection in gastric cancer development presents the opportunity for preventive screen-and-treat strategies. Invasive, endoscopy-based and non-invasive methods, including breath, stool and serological tests, are used in the diagnosis of H. pylori infection. Their use depends on the specific individual patient history and local availability. H. pylori treatment consists of a strong acid suppressant in various combinations with antibiotics and/or bismuth. The dramatic increase in resistance to key antibiotics used in H. pylori eradication demands antibiotic susceptibility testing, surveillance of resistance and antibiotic stewardship.

Individualized diagnosis and eradication therapy for Helicobacter pylori infection based on gene detection of clarithromycin resistance in stool specimens: A systematic review and meta-analysis

BACKGROUND

Empiric therapy for Helicobacter pylori infection results in significantly increased antibiotic resistance and decreased eradication efficacy. The genotypic testing of clarithromycin resistance from stool specimens is a promising method for individualized diagnosis and treatment. This study aimed to determine the status of research and application on this method through a systematic review and meta-analysis.

METHODS

PubMed, Embase, MEDLINE, and WAN FANG database were searched for relevant literature. The quality of included diagnostic articles was evaluated using the quality Assessment of Diagnostic Accuracy Studies-2 tool. A bivariate random-effect model was conducted to calculate the diagnostic accuracy of genotypic testing of clarithromycin resistance.

RESULTS

A total of 16 diagnostic-related were included and analyzed after exclusions. The pooled sensitivity and specificity of diagnostic meta-analysis were 0.93 (95% confidence interval [CI]: 0.90-0.96) and 0.98 (95% CI: 0.93-1.00), respectively. The area under the curve (AUC) of the summary receiver operating characteristic was 0.97 (95% CI: 0.95-0.98). The genotypic testing in stool samples had heterogeneous sensitivity (Q = 37.82, p < .01, I²  = 37.82) and specificity (Q = 60.34, p < .01, I²  = 93.72) in detecting clarithromycin resistance. Purification method, stool sample weight, real-time PCR, and antimicrobial susceptibility testing as reference accounted for the heterogeneity of pooled sensitivity, while patient age, purification method, stool sample weight, and real-time PCR for the heterogeneity of pooled specificity.

CONCLUSION

The genotypic testing of clarithromycin resistance from stool specimens is an accurate, convenient, noninvasive, and rapid detection technology, providing a definitive diagnosis of clarithromycin resistance and guiding the rational antibiotic selection.

Mistakes in the diagnosis and treatment of Helicobacter pylori infection in daily clinical practice

BACKGROUND

An adequate diagnostic and therapeutic approach to Helicobacter pylori (H. pylori) infection is the cornerstone to avoid overdiagnosis, overuse of health resources, and increase in antibiotic resistances. The aim of the study was to evaluate the most common errors in clinical practice and the associated risk factors.

MATERIALS AND METHODS

This is a retrospective observational study including patients with H. pylori infection and no previous treatment belonging to two defined areas of the National Health System in Spain; some of them were enrolled in the European Registry on H. pylori management (Hp-EuReg). Patients were attended by gastroenterologists between 2010 and 2019. According to current guidelines, we evaluated indications for H. pylori investigation, appropriateness of diagnostic test used in dyspeptic patients and discontinuation of surveillance after treatment.

RESULTS

A total of 1730 patients were included, receiving 2260 eradication regimens. H. pylori infection was investigated in 1.7% cases in absence of a formal indication. Oral endoscopy was incorrectly used in 56% of patients with dyspepsia under 55 years without alarm signs, and urea breath test (UBT) was incorrectly used in 22.4% of patients with dyspepsia ≥55 years or red flags. Levofloxacin containing regimens were used as first-line therapy in 7.5% of non-allergic to penicillin patients. After first-line failure, clarithromycin was repeated in 2.6% of the patients who received second-line therapy. Confirmatory test of H. pylori status was absent in 2.5% cases. Men, patients under 55 years, and patients diagnosed by UBT had a higher risk of not undergoing a confirmatory test.

CONCLUSIONS

Investigation of H. pylori infection by gastroenterologists is rare in absence of a formal indication; however, endoscopy is commonly used for dyspeptic patients <55 years without red flags and non-invasive tests are still used for dyspeptic patients ≥55 years or presenting alarm signs. Men, patients under 55 years, and patients diagnosed by UBT have an increased risk of being lost to follow-up after eradication treatment.

Helicobacter pylori Virulence Factors and Clarithromycin Resistance-Associated Mutations in Mexican Patients

Persistent infection with Helicobacter pylori (H. pylori) is an important factor in gastric diseases. The vacA and cagA virulence factors of H. pylori contribute to the development of these diseases. Triple therapy containing clarithromycin has been used to eradicate this infection. Unfortunately, resistance to this antibiotic is the primary cause of treatment failure. This study aimed to determine the prevalence of clarithromycin resistance-associated mutations and to assess the relationship between virulence factors and Mexican patients infected with H. pylori. The cagA and vacA genotypes were determined by multiplex PCR. Furthermore, a qPCR was used to identify mutations of the 23S rRNA gene. This study reported a prevalence of 84.3% of H. pylori among patients with gastric diseases, and the vacA s1m1/cagA+ genotype was the most frequent (44.8%) in antrum and corpus. Analysis of the 23S rRNA gene revealed a 19.8% prevalence of clarithromycin resistance-associated mutations. The most prevalent mutations were A2143G (56%) and A2142C (25%). A significant association (p < 0.05) between the A2142G and the vacA s1m1/cagA+ genotype was detected. In conclusion, we report a high prevalence (>15%) of clarithromycin resistance-associated mutations, and we found an association between the genotypes of virulence factors and a mutation in the 23S rRNA gene.

Modern Approaches to <i>H. pylori</i> Eradication Therapy in Adults (Literature Review and Resolution of Experts Council)

Aim: to analyze current approaches to H. pylori eradication therapy in adults and present the materials of Experts Council held on December 9, 2022 in Moscow.

General statements. H. pylori infection is the main etiological factor of gastritis, peptic ulcer, and gastric cancer. Eradication of H. pylori is recognized as a necessary measure to reduce the incidence of these diseases. The approaches to selecting an eradication regimen should be optimized to take into account epidemiological trends and achieve better treatment outcomes. The updated Maastricht VI Consensus Report presents the means to overcome the difficulties in selecting an approach to the treatment of H. pylori infection. However, eradication therapy remains challenging due to adverse events (primarily antibiotic-associated diarrhea), poor treatment tolerance and patient compliance. Eradication therapy can be optimized by supplementing treatment regimens with strain-specific probiotics that reduce adverse events, improve patient compliance and eradication rates, such as Saccharomyces boulardii CNCM I-745 strain with established efficacy.

Conclusion. The inclusion of certain probiotics in eradication regimens improves treatment tolerance, reduces the risk of adverse events, improves patient compliance and eradication rates.

Modern Approaches to <i>H. pylori</i> Eradication Therapy in Adults (Literature Review and Resolution of Experts Council)

Aim: to analyze current approaches to H. pylori eradication therapy in adults and present the materials of Experts Council held on December 9, 2022 in Moscow.

General statements. H. pylori infection is the main etiological factor of gastritis, peptic ulcer, and gastric cancer. Eradication of H. pylori is recognized as a necessary measure to reduce the incidence of these diseases. The approaches to selecting an eradication regimen should be optimized to take into account epidemiological trends and achieve better treatment outcomes. The updated Maastricht VI Consensus Report presents the means to overcome the difficulties in selecting an approach to the treatment of H. pylori infection. However, eradication therapy remains challenging due to adverse events (primarily antibiotic-associated diarrhea), poor treatment tolerance and patient compliance. Eradication therapy can be optimized by supplementing treatment regimens with strain-specific probiotics that reduce adverse events, improve patient compliance and eradication rates, such as Saccharomyces boulardii CNCM I-745 strain with established efficacy.

Conclusion. The inclusion of certain probiotics in eradication regimens improves treatment tolerance, reduces the risk of adverse events, improves patient compliance and eradication rates.

Personalized Approach in Eradication of Helicobacter pylori Infection

The increase in antibiotic resistance to Helicobacter pylori (H. pylori) is associated with a decrease in the effectiveness of eradication therapy. Although some success has been achieved by adjusting therapeutic regimens according to local data on resistance to certain antibiotics, a new approach is needed to ensure a better therapeutic response. Tailored therapy, based on sensitivity tests to antibiotics, is increasingly proving to be a superior therapeutic option, even as a first-line therapy. Moreover, the recently published Maastricht VI guidelines emphasize utilizing a susceptibility-guided strategy in respect to antibiotic stewardship as the first choice for eradication therapy. In addition, polymerase chain reaction (PCR) technology is becoming a standard tool in the diagnosis of H. pylori infections through non-invasive testing, which further optimizes the eradication process. We provide a review regarding the current position of the individualized approach in eradication therapy and its future prospects. Based on novel understandings, the personalized approach is an effective strategy to increase the successful eradication of H. pylori infections.

Management of Helicobacter pylori infection: the Maastricht VI/Florence consensus report

Helicobacter pyloriInfection is formally recognised as an infectious disease, an entity that is now included in the International Classification of Diseases 11th Revision. This in principle leads to the recommendation that all infected patients should receive treatment. In the context of the wide clinical spectrum associated with Helicobacter pylori gastritis, specific issues persist and require regular updates for optimised management.The identification of distinct clinical scenarios, proper testing and adoption of effective strategies for prevention of gastric cancer and other complications are addressed. H. pylori treatment is challenged by the continuously rising antibiotic resistance and demands for susceptibility testing with consideration of novel molecular technologies and careful selection of first line and rescue therapies. The role of H. pylori and antibiotic therapies and their impact on the gut microbiota are also considered.Progress made in the management of H. pylori infection is covered in the present sixth edition of the Maastricht/Florence 2021 Consensus Report, key aspects related to the clinical role of H. pylori infection were re-evaluated and updated. Forty-one experts from 29 countries representing a global community, examined the new data related to H. pylori infection in five working groups: (1) indications/associations, (2) diagnosis, (3) treatment, (4) prevention/gastric cancer and (5) H. pylori and the gut microbiota. The results of the individual working groups were presented for a final consensus voting that included all participants. Recommendations are provided on the basis of the best available evidence and relevance to the management of H. pylori infection in various clinical fields.

Clinical Factors Implicated in Antibiotic Resistance in Helicobacter pylori Patients

Helicobacter pylori is a common gastric pathogen associated with multiple clinical syndromes, including cancer. Eradication rates of H. pylori remain suboptimal despite the progress made in the past few decades in improving treatment strategies. The low eradication rates are mainly driven by antibiotic resistance of H. pylori. Non-invasive molecular testing to identify patients with antibiotic-resistant H. pylori represents a promising therapeutic avenue, however this technology currently remains limited by availability, costs, and lack of robust validation. Moreover, there is insufficient evidence to demonstrate that resistance-testing-based treatment approaches are superior to appropriately designed empiric strategies. Consensus guidelines recommend use of proven locally effective regimens; however, eradication data are inconsistently generated in several regions of the world. In this review, we describe several clinical factors associated with increased rates of antibiotic resistant H. pylori, including history of previous antibiotic exposure, increasing age, female gender, ethnicity/race, extent of alcohol use, and non-ulcer dyspepsia. Assessment of these factors may aid the clinician in choosing the most appropriate empiric treatment strategy for each patient. Future study should aim to identify locally effective therapies and further explore the clinical factors associated with antibiotic resistance.

Comparison of tailored Helicobacter pylori eradication versus modified bismuth quadruple therapy in Korea: a randomized controlled trial

OBJECTIVES

We aimed to compare the success rate, adverse drug events, and cost-effectiveness of tailored Helicobacter pylori eradication and modified bismuth-containing quadruple therapy.

METHODS

The diagnosis of H. pylori infection was randomly based on either rapid urease test (RUT) or dual priming oligonucleotide (DPO)-based multiplex polymerase chain reaction (PCR) in 1:1 ratio. According to the presence of point mutations that cause clarithromycin resistance, patients in the tailored therapy (TT) group received standard triple therapy or classic bismuth quadruple therapy. Patients with positive RUT results received 40 mg pantoprazole, 1000 mg amoxicillin, 750 mg metronidazole, and 600 mg bismuth subcitrate twice daily for 14 days (PAM-B therapy).

RESULTS

Between the TT (n = 141) and PAM-B groups (n = 141), H. pylori eradication rate did not differ significantly according to intention-to-treat (TT: 80.9% vs. PAM-B: 85.8%, P = 0.262), modified intention-to-treat (TT: 89.1% vs. PAM-B: 91.0%, P = 0.606), and per-protocol (TT: 89.0% vs. PAM-B: 93.5%, P = 0.198) analyses. The average cost for successful eradication was higher in the TT group than in the PAM-B group ($340.7 vs. $263.9 per patient).

CONCLUSION

PAM-B therapy exhibits similar efficacy and improved cost-effectiveness compared to TT based on the results of DPO-PCR tests.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov identifier is NCT05002595.

Molecular Detection of Antibiotic-Resistant Helicobacter pylori

Antimicrobial susceptibility testing (AST) for H. pylori is essential to accurately assess the prevalence of antibiotic resistance in each population. Antibiotic resistance rates form the basis of local guidelines for H. pylori treatment and AST may also be used as a personalized medicine approach to tailor therapy. This chapter provides an update on global antibiotic resistance rates and describes molecular mechanisms that confer H. pylori antibiotic resistance. An overview on the advantages and limitations of molecular AST using both invasive and noninvasive approaches is also provided.

Genomic Analysis of Antimicrobial Resistance Genotype-to-Phenotype Agreement in Helicobacter pylori

Antimicrobial resistance (AMR) in Helicobacter pylori is increasing and can result in treatment failure and inappropriate antibiotic usage. This study used whole genome sequencing (WGS) to comprehensively analyze the H. pylori resistome and phylogeny in order to characterize Israeli H. pylori. Israeli H. pylori isolates (n = 48) underwent antimicrobial susceptibility testing (AST) against five antimicrobials and WGS analysis. Literature review identified 111 mutations reported to correlate with phenotypic resistance to these antimicrobials. Analysis was conducted via our in-house bioinformatics pipeline targeting point mutations in the relevant genes (pbp1A, 23S rRNA, gyrA, rdxA, frxA, and rpoB) in order to assess genotype-to-phenotype correlation. Resistance rates of study isolates were as follows: clarithromycin 54%, metronidazole 31%, amoxicillin 10%, rifampicin 4%, and levofloxacin 2%. Genotype-to-phenotype correlation was inconsistent; for every analyzed gene at least one phenotypically susceptible isolate was found to have a mutation previously associated with resistance. This was also observed regarding mutations commonly used in commercial kits to diagnose AMR in H. pylori cases. Furthermore, 11 novel point mutations associated with a resistant phenotype were detected. Analysis of a unique set of H. pylori isolates demonstrates that inferring resistance phenotypes from WGS in H. pylori remains challenging and should be optimized further.

One-step synthesis of a carbon dot-based fluorescent probe for colorimetric and ratiometric sensing of tetracycline

Carbon dots (CDs) with blue fluorescence were synthesized using indole-3-butyric acid and l-tryptophan using a one-step hydrothermal method. The CDs were further employed as a fluorescent sensor with high selectivity for colorimetric and ratiometric detection of tetracycline (TC) in water. The limit of detection (LOD) was found to be 0.33 μM for TC with R² = 0.98387. Besides, the CDs could be applied in practical water samples and showed good recovery.

Empirical or susceptibility-guided treatment for Helicobacter pylori infection? A comprehensive review

Although susceptibility-guided therapy is frequently recommended for Helicobacter pylori infection, the evidence available to date supporting this strategy is limited. The aim of the present article is to review the advantages and limitations of the susceptibility-guided and the empirical strategies to treat this infection. We performed a bibliographic search to identify studies investigating H. pylori susceptibility-guided therapy. Culture is not the only way to assess antibiotic resistance, as different polymerase chain reaction-based approaches have been developed as alternative methods. For detecting H. pylori antimicrobial resistance, a molecular approach based on a stool sample might enable more convenient, time-saving methods. Unfortunately, the antimicrobial susceptibility cannot be obtained in all cases. Furthermore, antibiotic susceptibility testing in clinical practice yields useful information only for a few antibiotics: clarithromycin, metronidazole, and quinolones. In addition, susceptibility towards clarithromycin and metronidazole in vitro does not necessarily lead to eradication in vivo. In the case of H. pylori therapy failure, we should not re-administer any of the antibiotics against which H. pylori has probably become resistant. Our updated meta-analysis showed that susceptibility-guided treatment is not better than empirical treatment of H. pylori infection in first-line therapy if the most updated quadruple regimens are empirically prescribed, and similar efficacy results were also demonstrated with the two strategies for second-line therapy. Cumulative H. pylori eradication rate with several successive rescue therapies empirically prescribed reaches almost 100%. Finally, the studies that have evaluated the cost-effectiveness of the susceptibility-guided treatment have achieved contradictory results. In summary, we can conclude that the evidence is too limited to support the generalized use of susceptibility-guided therapy for H. pylori treatment in routine clinical practice, either as first-line or as rescue treatment. Nevertheless, it would be recommended that susceptibility tests are performed routinely, even before prescribing first-line treatment, in specialized centers with an interest in H. pylori management.

Genotype profiles of Helicobacter pylori from gastric biopsies and strains with antimicrobial-induced resistance

BACKGROUND AND AIMS

The genotypic method could significantly shorten the time needed to obtain antibiotic susceptibility data for Helicobacter pylori. The aim of this study was to explore the profile of H. pylori from gastric biopsies and strains with antibiotic-induced resistance.

METHODS

A total of 124 gastric biopsies were used to perform gene sequencing and to perform bacterial culture and susceptibility testing. Seven susceptible strains were selected to develop resistance to clarithromycin, levofloxacin, and metronidazole. Four susceptible strains were selected to transfer candidate mutations. The genotype profiles of these groups were analyzed by sequencing analysis. The antibiotic susceptibility of these strains was detected using the E-test method.

RESULTS

Phenotypic resistance to clarithromycin, levofloxacin, and metronidazole was observed in 35.5%, 40.0%, and 79.8% strains, respectively. Point mutations in 23 S rRNA, gyrA, and rdxA genes were observed in 39.5%, 38.7%, and 86.3% of gastric biopsies, respectively. The A2143G mutation in the 23S rRNA occurs in most clarithromycin-resistant samples. The A2142C point mutation showed a higher efficacy than A2142G and A2143G for inducing clarithromycin resistance. The D91N and N87K mutations in gyrA occurs in most levofloxacin-resistant samples, and double point mutations showed a higher efficacy than single mutations for inducing levofloxacin resistance. Phenotypic resistance and mutations in rdxA lacked consistency.

CONCLUSION

Genotype-based gastric biopsy analysis was reliable for determining clarithromycin and levofloxacin resistance. A2143G in 23S rRNA and N87K/D91N in the gyrA gene occurred in most resistant strains. Mutations in the rdxA gene were not good indicators of metronidazole resistance.

Phenotype and Molecular Detection of Clarithromycin and Levofloxacin Resistance in Helicobacter pylori Clinical Isolates in Beijing

Introduction

Understanding drug resistance is important in drug selection for Helicobacter pylori (H. pylori) eradication, and drug resistance data are lacking in Beijing.

Purpose

This cross-sectional study aimed to isolate H. pylori from patients with gastroduodenal diseases and to analyze drug resistance to clarithromycin (CLA) and levofloxacin (LEV), which are used frequently in China.

Patients and Methods

One hundred and seventy-six patients with gastroduodenal diseases undergoing gastroduodenoscopy were selected by convenient sampling. Gastric mucosa samples were cultured and sub-cultured using a new medium broth. Active H. pylori strains were confirmed by microscopy observation as Gram-negative curved bacilli with positive test results for urease, oxidase, and catalase, and H. pylori 16S rRNA amplification by polymerase chain reaction (PCR). CLA and LEV resistance was identified by minimum inhibitory concentration (MIC) tests and sequencing of 23S rRNA, gyrA, and gyrB genes.

Results

From the 176 clinical samples, 112 (112/176, 63.6%) were confirmed with H. pylori infection and 65 (65/176, 36.9%) active H. pylori strains were obtained and further confirmed by MIC assay. Overall, the rates of CLA-resistant and LEV-resistant mutations in the 112 samples were 50.9% and 33.0%, respectively. Mutation related to CLA resistance was A2143G in the 23S rRNA gene and mutations associated with LEV resistance were N87K, D91G, and D91Y in the gyrA gene. Of 112 samples, 22 (19.6%) presented dual resistance to CLA and LEV. Resistance of the H. pylori strains to CLA (r=0.846, P<0.001) and LEV (r=0.936, P<0.001) had a strong correlation in phenotypic and genotypic level.

Conclusion

The results indicated that resistance of CLA and LEV is severe among patients with gastroduodenitis. A good consistency could be found as to drug resistance between genotypic or phenotypic assay, suggested extending the detection of H. pylori drug resistance from the MIC method to a genotypic assay.

Susceptibility-guided bismuth quadruple therapies for resistant Helicobacter pylori infections

Increasing Helicobacter pylori resistance to antibiotics has ledthat molecular testing is appropriate as a sub to adoption of seven different bismuth quadruple therapies (BQT) in China without differentiation of first-line or second-line regimens. The objective of this study was to evaluate the efficacy of susceptibility-guided BQT for patients who had experienced previous treatment failures. A total of 133 patients was included and H. pylori was successfully cultured from 101 patients (75.9%) for subsequent antimicrobial susceptibility testing (AST). Based on the AST results, 88 patients completed one of five AST-guided 14-day BQT regimens: esomeprazole and bismuth colloidal pectin, along with either, amoxicillin and clarithromycin (EBAC), amoxicillin and levofloxacin (EBAL), amoxicillin and furazolidone (EBAF), amoxicillin and tetracycline (EBAT), or tetracycline and furazolidone (EBTF). H. pylori eradication rates were 100% for EBAC (5/5), EBAL (13/13), EBAF (14/14), and EBTF (43/43), but 76.9% for EBAT (10/13). The three patients that failed the EBAT regimen were all cured after subsequent treatment with the EBTF regimen. Our study demonstrates the excellent efficacy of the AST-guided BQT for referred H. pylori patients, and that the current EBAT regimen, used in clinics, needs to be optimized. In addition, 57 of the isolates were subjected to whole-genome sequencing. Analysis of the sequences revealed that point mutations in 23S rRNA correlated well with the phenotypic clarithromycin resistance with a concordance of 91.2%, while the concordance between phenotypic levofloxacin resistance and gyrA point mutations was 82.3%. This suggests that molecular testing is appropriate as a substitute for AST as a more rapid and cost-effective method for determining clarithromycin and levofloxacin resistance in Chinese patients.

Treatment of Helicobacter pylori

PURPOSE OF REVIEW

Helicobacter pylori eradication has become more challenging over the past decade due to increasing antimicrobial resistance, especially to clarithromycin and levofloxacin. We identified 508 recent publications on H. pylori treatment (published between January 2018 and June 2019), focusing on the most highly clinically relevant for this review.

RECENT FINDINGS

Declining H. pylori eradication rates with clarithromycin triple therapy have led to most guidelines recommending 14 days bismuth-based quadruple therapy or concomitant therapy as the best initial empiric regimen. Substituting amoxicillin for tetracycline or metronidazole in quadruple therapy, and a three-in-one pill version of the regimen, also appear effective. Vonoprazan, a potent acid inhibitor, can overcome much clarithromycin resistance in triple therapy. High-dose dual therapy (proton pump inhibitor with amoxicillin) is a promising alternative approach. Reviewing resistance patterns to select suitable first-line empiric therapies is important in high resistance regions. Molecular methods to evaluate H. pylori antimicrobial susceptibility promise to be simpler than standard microbiological culture. The cost-effectiveness of antimicrobial susceptibility testing in refractory cases remains unproven.

SUMMARY

Updating clinicians treating H. pylori is important to combat the emerging problems of multidrug antimicrobial resistance in H. pylori strains. Truly novel approaches to H. pylori eradication are needed.

Helicobacter pylori resistance to current therapies

PURPOSE OF REVIEW

Helicobacter pylori eradication rates have fallen in recent years, mainly because of the emergence of antibiotic-resistant infections. Indeed the WHO has recently designated clarithromycin-resistant H. pylori infection a high priority for antibiotic resistance research and development. This review aims to discuss the most up-to-date information on the methods to detect H. pylori antibiotic resistance, the recent data on resistance rates, and the most appropriate treatment strategies to overcome antibiotic resistance.

RECENT FINDINGS

There has been active research into the development and assessment of genotypic diagnostic assays for both the invasive and noninvasive detection of antibiotic-resistant infection. There are regional variations in the prevalence of H. pylori antibiotic resistance. Primary resistance rates in general are on the rise and high rates of clarithromycin resistance (>15%) have been reported in many parts of the world.

SUMMARY

Optimizing antimicrobial susceptibility testing by both invasive and noninvasive means is crucial to accurately evaluate resistance rates for the optimization of both regional and personalized H. pylori treatment strategies.

Enzymatic Transition States and Drug Design

Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.