Helicobacter pylori Primary and Secondary Genotypic Resistance to Clarithromycin and Levofloxacin Detection in Stools: A 4-Year Scenario in Southern Italy

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.

Concomitant and Bismuth Quadruple Therapy for Helicobacter pylori Eradication in Southern Italy: Preliminary Data from a Randomized Clinical Trial

Concomitant therapy (CT) and bismuth quadruple therapy (BQT) are recommended in geographical areas with high clarithromycin resistance for Helicobacter pylori (H. pylori) eradication. We compared CT and BQT as the first lines of treatment in a randomized controlled trial. Consecutive patients with H. pylori diagnosed by concordance of both a urea breath test and histology were recruited. For BQT, patients received 3 PyleraTM capsules q.i.d.; for CT, 1000 mg of amoxicillin b.i.d, 500 mg of clarithromycin b.i.d and 500 mg of metronidazole b.i.d. As a proton pump inhibitor, 40 mg of pantoprazole b.i.d was administered. Both regimens lasted 10 days. In total, 46 patients received CT and 38 BQT. Both groups were comparable for age (p = 0.27) and sex (p = 0.36). We did not record any drop outs; therefore, the intention to treat and per protocol rates coincided. The most common symptoms were heartburn and post-prandial fullness, which were equally present in both groups. The success rate was 95.6% for CT and 100% for BQT (p = 0.56). Side effects were recorded in 23.9% and 31.6% of patients in the CT and BQT arms, respectively (p = 0.47). The most common ones were abdominal pain (8) and diarrhea (6). In conclusion, CT and BQT are equally effective in our area with high clarithromycin resistance, southern Italy, and showed comparable safety.

Helicobacter pylori Secondary Antibiotic Resistance after One or More Eradication Failure: A Genotypic Stool Analysis Study

Helicobacter pylori (H. pylori) antibiotic resistance is the leading cause for unsuccessful eradication therapy. After one or more failures, the chance of encountering secondary antibiotic resistance increases. The aim of this study was to characterize genotypic secondary resistance in a cohort of southern Italian H. pylori patients with at least one previous failure. Such patients collected stool samples using a dedicated kit (THD fecal testTM), and bacterial DNA was extracted and amplified using RT-PCR. Resistance to clarithromycin, amoxicillin, metronidazole, levofloxacin, and tetracycline was assessed using a high-resolution melting curve. We enrolled 50 patients. A total of 72% of patients failed one previous antibiotic course, 16% failed two, 10% failed three, and 2% failed four. The rate of secondary antibiotic resistance was 16% for clarithromycin, 18% for metronidazole, 14% for amoxicillin, 14% for levofloxacin, and 2% for tetracycline. Among the eight clarithromycin-resistant patients, five (62.5%) previously received a clarithromycin-based regimen. The same rate was 33.3% (3/9) for metronidazole. The only tetracycline-resistant patient had received Pylera. In conclusion, our data seem to show that, even though secondary resistance is not very high, resistance to clarithromycin could be very likely related to previous exposure to this antibiotic.

Molecular Characterization and Mutational Analysis of Clarithromycin- and Levofloxacin-Resistance Genes in Helicobacter pylori from Gastric Biopsies in Southern Croatia

Point mutations in the 23S rRNA, gyrA, and gyrB genes can confer resistance to clarithromycin (CAM) and levofloxacin (LVX) by altering target sites or protein structure, thereby reducing the efficacy of standard antibiotics in the treatment of Helicobacter pylori infections. Considering the confirmed primary CAM and LVX resistance in H. pylori infected patients from southern Croatia, we performed a molecular genetic analysis of three target genes (23S rRNA, gyrA, and gyrB) by PCR and sequencing, together with computational molecular docking analysis. In the CAM-resistant isolates, the mutation sites in the 23S rRNA gene were A2142C, A2142G, and A2143G. In addition, the mutations D91G and D91N in GyrA and N481E and R484K in GyrB were associated with resistance to LVX. Molecular docking analyses revealed that mutant H. pylori strains with resistance-related mutations exhibited a lower susceptibility to CAM and LVX compared with wild-type strains due to significant differences in non-covalent interactions (e.g., hydrogen bonds, ionic interactions) leading to destabilized antibiotic-protein binding, ultimately resulting in antibiotic resistance. Dual resistance to CAM and LVX was found, indicating the successful evolution of H. pylori resistance to unrelated antimicrobials and thus an increased risk to human health.

Surveillance of Helicobacter pylori resistance over 22 Years (2000-2021) in Northern Spain

OBJECTIVES

Helicobacter pylori gastritis is considered an infectious disease, regardless of symptoms and stage of disease. Most consensus documents recommend empirical therapy based on local antimicrobial susceptibility patterns. We aimed to provide clinically useful information about primary and secondary antimicrobial resistance to antimicrobials commonly prescribed for H. pylori.

METHODS

Overall, 31,406 gastroduodenal biopsies and 2,641 string tests from patients over 15 years of age were plated on selective media, isolating H. pylori in 36.7% of biopsies and 50.7% of string tests. Susceptibility testing could be performed in 96.6% (12,399/12,835) of H. pylori isolates. Polymerase chain reaction (PCR) was also used to detect H. pylori and its resistance to clarithromycin, providing susceptibility data for 112 patients with negative culture results.

RESULTS

Resistance to amoxicillin and tetracycline was unusual (0.6% and 0.2%, respectively). Rates of primary resistance to clarithromycin and metronidazole remained steady over the 22-year study period, at around 14% for clarithromycin and 30% for metronidazole, while primary resistance to levofloxacin tripled (from 7.6% in 2000 to 21.7% in 2021, P < 0.001) and increased with patient age. Notably, 1.8% of isolates were multiresistant to clarithromycin, metronidazole, and levofloxacin. Overall, secondary resistance rates were higher (P < 0.0001) than primary resistance rates for clarithromycin (42.5% vs 14.1%), metronidazole (40.9% vs 32%), and levofloxacin (21.5% vs 17.1%).

CONCLUSION

Determination of susceptibility for H. pylori by culture and/or PCR in patients undergoing endoscopy could facilitate the implementation of tailored therapy and guide the choice of empirical therapy when susceptibility testing cannot be performed, potentially helping limit the emergence of antimicrobial resistance.

Unpacking the Racial Gap: Helicobacter pylori Infection Clearance Among Different Racial Groups

Introduction Helicobacter pylori (H. pylori) is a bacteria causing chronic stomach infections, influenced by various factors, including host traits and bacterial virulence. It uses both urease-dependent and independent mechanisms to survive acidic gastric environments. Management entails diagnosis, treatment, and eradication verification. Combining drugs is key to overcoming resistance and ensuring bacteria elimination, thus preventing recurrence and complications. H. Pylori eradication mitigates gastric cancer risk and alleviates symptoms. Racial disparities persist despite declining H. pylori and gastric cancer incidence in the United States (US). African Americans (AA) have higher gastric cancer risks than non-Hispanic Whites. Addressing these disparities is crucial to protect high-risk populations. Methods This study retrospectively compiled H. pylori infection data from 2009 to 2022, categorized by race. Propensity score matching balanced initial group characteristics before analysis. Chi-squared and odds ratio tests were used on the cohort, with Kaplan Meier and Log Rank methods evaluating disease clearance in ethnic groups. Data were extracted from the Sunrise Electronic Medical Record software, including patient demographics, health details, and treatment specifics. Patients aged 18-65 with H. pylori infection at Nassau University Medical Center, who followed their treatment, were selected. Data were processed using Statistical Package for the Social Sciences (SPSS) and RStudio software. Results The study initially included 10,040 H. pylori-diagnosed patients, with 9,288 meeting the study's criteria after attrition. Predominantly female (64.7%), the cohort was racially diverse. A longer disease clearance time was noted among Hispanics (p=0.044). Binomial logistic regression analysis identified influential factors like high school graduation rates, poverty level income, and language proficiency on disease clearance. An odds ratio analysis further emphasized language barriers (HR 0.346, p=0.043) and education status (HR 0.756, p=0.025) as primary covariates impacting disease clearance, underlining the role of socio-economic factors and language proficiency in health outcomes. Conclusion The study highlights racial disparities in H. pylori clearance rates, particularly among Hispanics, necessitating culturally sensitive interventions. It advocates for improved diagnostics, increased healthcare access, and social determinants of health-focused initiatives. It identifies socio-economic status and language proficiency as key factors impacting health outcomes, calling for actions to bridge these disparities. Addressing these differences can decrease healthcare inequalities and economic burden, improving overall health outcomes and reducing costs associated with H. pylori clearance.

The State of the Art of Molecular Fecal Investigations for Helicobacter pylori (H. pylori) Antibiotic Resistances

A new paradigm shift for the treatment of Helicobacter pylori (H. pylori) infection would be timely due to a progressive increase in antibiotic resistance. Such a shift in the perspective of the H. pylori approach should include the preliminary assessment of antibiotic resistance. However, the availability of sensitivity tests is not widespread and the guidelines have always indicated empirical treatments without taking into account the need to make sensitivity tests accessible, i.e., the necessary starting point for improving results in different geographical areas. Currently, the traditional tools for this purpose (culture) are based on performing an invasive investigation (endoscopy) and often involve technical difficulties; thus, they were only confined to the settings where multiple attempts at eradication have failed. In contrast, genotypic resistance testing of fecal samples using molecular biology methods is much less invasive and more acceptable to patients. The purpose of this review is to update the state of the art of molecular fecal susceptibility testing for the management of this infection and to extensively discuss the potential benefits of their large-scale deployment, i.e., novel pharmacological opportunities.

High-dose amoxicillin-proton pump inhibitor dual therapy as first-line treatment for Helicobacter pylori infection in Northwest China: A prospective, randomised controlled trial

AIMS

We aimed to assess the eradication efficacy and factors that influencing it of high-dose dual therapy (HDDT) in Gansu region, Northwest China.

METHODS

A total of 216 treatment-naive patients with Helicobacter pylori infection were randomly assigned to two groups for the 14-day eradication treatment: the HDDT group (amoxicillin 750 mg q.i.d. and esomeprazole 40 mg t.i.d.) and the amoxicillin and clarithromycin-containing bismuth quadruple therapy group (ACBQT: esomeprazole 20 mg, bismuth potassium citrate 2 g, amoxicillin 1 g, and clarithromycin 500 mg; b.i.d.). The eradication rates, adverse effects and patient compliance of these two groups were compared. Eradication efficacy was determined by ¹³ C urea breath test (¹³ C UBT) 4-8 weeks after finishing treatment. Antibiotic resistance was determined by the Epsilometer testing (E-test) method.

RESULTS

The eradication rates for the HDDT and ACBQT groups were 71.0% and 74.7% (P = .552) by per-protocol analysis, and 65.7% and 68.5% (P = .664) by intention-to-treat analysis. The overall adverse event rates in the HDDT and ACBQT groups were 2.0% and 43.4% (P < .001), respectively. The resistance rates to amoxicillin, clarithromycin, tetracycline, levofloxacin and metronidazole were 15.2%, 42.0%, 5.4%, 35.7% and 83.0%, respectively. Amoxicillin resistance and delta over baseline (DOB) of ¹³ C UBT ≥ 20 before treatment significantly reduced the eradication rate in 112 participants with H. pylori cultured.

CONCLUSION

The HDDT as first-line treatment for H. pylori was unsatisfactory in Gansu. Amoxicillin resistance and DOB of ¹³ C UBT ≥ 20 before treatment were significantly correlated with H. pylori eradication failure.

Clinical Implications of Helicobacter pylori Antibiotic Resistance in Italy: A Review of the Literature

Helicobacter pylori (H. pylori) resistance to antibiotics has increased worldwide in recent decades, especially to clarithromycin. As a result, the World Health Organization (WHO) identified clarithromycin-resistant H. pylori as a "high priority" pathogen in 2017. As international guidelines recommend empirical therapy as first-line treatment, it is crucial to know local resistance rates and history of antibiotic use to determine the most appropriate first-line antibiotic treatment. Italy is one of the European countries with the highest prevalence of H. pylori infection and the highest percentage of antibiotic-resistant H. pylori. The aim of this review is to summarize all data on H. pylori antibiotic resistance in Italy in order to quantify the current rate and determine the most effective therapeutic approach. The study confirms an elevated level of resistance to clarithromycin, metronidazole, and levofloxacin in Italy. In addition, our results show a satisfactory eradication rate for a bismuth-based regimen when used as first- or second-line treatment. Naive patients are also successfully treated with clarithromycin-based quadruple therapies. Considering the good results of bismuth-based therapy as recovery therapy, this argues for the potential use of clarithromycin quadruple therapy as a first-line treatment.

Effect of metronidazole resistance on Helicobacter pylori eradication regimens

OBJECTIVES

Guidelines suggest bismuth-containing quadruple therapy (BQT) or concomitant therapy (CT) as first-line therapy in our geographic area. Both schedules contain metronidazole. We aimed to evaluate the effect of metronidazole resistance to Helicobacter pylori (H. pylori) eradication therapy.

METHODS

We recruited treatment-naïve subjects with H. pylori infection who received either CT or BQT during January 2020 and December 2021. Before therapy, a fecal sample was collected using the THD fecal test device from each patient. H. pylori DNA was extracted and mutations of rdxA and frxA genes and A2143G for metronidazole and clarithromycin resistance were investigated using real-time polymerase chain reaction with a high-resolution melting curve.

RESULTS

Ninety-six patients were enrolled, including 29 received BQT and 67 received CT. The overall eradication rate was 94.8% (100% for BQT and 92.5% for CT). Metronidazole resistance was found in 18 (18.8%) subjects, while clarithromycin resistance was found in 19 (19.8%). All 18 patients with metronidazole resistance achieved successful eradication (five treated with BQT and 13 with CT). The eradication rate in metronidazole-sensitive strains was 93.6%. Of these, 24 received BQT with 100% success, and 54 had CT with five failures (successful eradication in 90.7%). Two patients with treatment failure were resistant to clarithromycin, and the remaining three were susceptible to both clarithromycin and metronidazole. No statistical significance was observed in the eradication rate between metronidazole-resistant and -sensitive strains (100% vs 93.6%, P = 0.58).

CONCLUSION

Metronidazole resistance does not influence the eradication rate of BQT and CT regimens in our geographical area, even if such results need to confirmed in a larger sample.

Management of Helicobacter pylori infection: Guidelines of the Italian Society of Gastroenterology (SIGE) and the Italian Society of Digestive Endoscopy (SIED)

Helicobacter pylori infection is very common and affects more than one-third of adults in Italy. Helicobacter pylori causes several gastro-duodenal diseases, such as gastritis, peptic ulcer and gastric malignancy, and extra-gastric diseases. The eradication of the bacteria is becoming complex to achieve due to increasing antimicrobial resistance. To address clinical questions related to the diagnosis and treatment of Helicobacter pylori infection, three working groups examined the following topics: (1) non-invasive and invasive diagnostic tests, (2) first-line treatment, and (3) rescue therapies for Helicobacter pylori infection. Recommendations are based on the best available evidence to help physicians manage Helicobacter pylori infection in Italy, and have been endorsed by the Italian Society of Gastroenterology and the Italian Society of Digestive Endoscopy.

Empiric "Three-in-One" Bismuth Quadruple Therapy for Second-Line Helicobacter pylori Eradication: An Intervention Study in Southern Italy

The eradication of Helicobacter pylori (H. pylori) may be difficult due to antibiotic resistance. Indeed, after one failure, a second-line therapy is needed and a bismuth containing quadruple therapy (BQT) with a three-in-one capsule formulation is becoming very popular. Therefore, we aimed to evaluate effectiveness and safety of BQT as a second-line therapy. We recruited consecutive patients with one therapy failure. For ten days patients received the three-in-one BQT Pylera^® therapy, in combination with a proton-pump inhibitor (PPI), decided at the choice of the investigator, at full dose bid. The eradication rate was calculated by intention-to-treat (ITT) and per-protocol (PP)analyses and 95% confidence intervals (CI) were calculated. Seventy-three patients were recruited, 41 females and 32 males (mean age 53.0±13.1 years). Fifty-five patients failed triple therapy with amoxicillin and clarithromycin and the remaining 18 received sequential therapy. Seventy-two patients consumed at least 90% of the capsules, while only one did not complete the therapy due to adverse events (nausea and diarrhea). By ITT analysis, BQT was successful in 62 subjects (eradication rate 84.9%, 95%CI 76.7–93.1%). By PP analysis, the eradication rate was 86.1% (95%CI 78.1–94.1%).Adverse events were observed in 14 subjects (20.5%).In conclusion, our report confirmed that BQT is effective as an empiric second-line regimen.

Levofloxacin-based therapy as an efficient alternative for eradicating Helicobacter pylori infection in Iran: a systematic review and meta-analysis

OBJECTIVES

Despite excessive resistance of Helicobacter pylori to clarithromycin among Iranian population, unfortunately, clarithromycin-based therapy is still prescribed in Iran. Recent studies have shown high rates of H. pylori eradication in patients treated with levofloxacin. The main purpose of this study was to compare the effect of levofloxacin with clarithromycin on the eradication of H. pylori infection in Iranian population.

METHODS

A comprehensive meta-analysis was done for the relevant cohort studies and clinical trials to compare the therapeutic effects of levofloxacin with clarithromycin in Iranian population. We pooled the data using odds ratio corresponding to 95% confidence intervals to find the clinical efficacy of levofloxacin versus clarithromycin to treat H. pylori infection. The heterogeneity and publication bias were also measured for the included studies.

RESULTS

A total of 13 studies were included in the quantitative synthesis. Eradication rate in patients receiving levofloxacin and clarithromycin were 75% and 66.3%, respectively (OR: 1.76; 95% CI: 1.40-2.20). In addition, in the subgroup analysis, it was confirmed that cure rate is relatively higher in levofloxacin-treated cases. However, there is significant heterogeneity as well as publication bias, thus, the results need to be interpreted with caution.

CONCLUSIONS

We found that the success of levofloxacin treatment was significantly higher than that of clarithromycin. Therefore, it is suggested that clarithromycin-based triple therapy be replaced by levofloxacin-based triple therapy in countries with high resistance rate to clarithromycin such as Iran. Nevertheless, findings of the present study need to be approved with larger investigation on Iranian population.

Development and Validation of Multiplex Quantitative PCR Assay for Detection of Helicobacter pylori and Mutations Conferring Resistance to Clarithromycin and Levofloxacin in Gastric Biopsy

Aims and Objectives

More than half of the world's population is infected with Helicobacter pylori, which can cause chronic gastritis. WHO has regarded clarithromycin-resistant H. pylori as a high priority pathogen. Hence, accurate diagnosis and detection of clarithromycin- and levofloxacin-resistant H. pylori strains is essential for proper management of infection. The objective of this study was to develop and optimize multiplex quantitative PCR assay for detection of mutations associated with clarithromycin and levofloxacin resistance in H. pylori directly from the gastric biopsies.

Materials and Methods

Specific primers and probes were designed to amplify ureA and mutations in 23S rRNA and gyrA genes. Singleplex and triplex qPCR assays were optimized and the assay's sensitivities and specificities were determined. The optimized multiplex qPCR assay was performed on 571 gastric biopsies.

Results

In this study, 14.7% (84/571) of the gastric biopsies were positive for H. pylori by conventional methods and 23.8% (136/571) were positive by the ureA-qPCR with 96.4% sensitivity and 88.5% specificity, while the +LR and -LR were 8.72 and 0.04, respectively. The ureA-positive samples (n=136) were subjected to multiplex qPCR which detected A2142G and A2143G mutations in the 23S rRNA gene (20.6%, 28/136) conferring clarithromycin resistance and gyrA mutations N87K, N87I, D91N, and D91Y (11.8%, 16/136) leading to levofloxacin resistance. The sensitivity and specificity of qPCR of 23S rRNA gene were 100% and 98.7%, respectively, while 100% and 99.8% for qPCR of gyrA, respectively.

Conclusion

The effectiveness of this qPCR is that it is sensitive in detecting low bacterial load and will help in timely detection of clarithromycin- and levofloxacin-resistant strains, especially in case of mixed infections. Since it is culture independent, it can inform clinicians about antibiotics to be included in the first-line therapy, thereby improving the management of H. pylori infection at a much greater pace.

Treatment Approach of Refractory Helicobacter pylori Infection: A Comprehensive Review

H. pylori is the most common infection in the world and is associated with gastrointestinal and extra-gastrointestinal manifestations, including peptic ulcer disease, gastrointestinal bleeding, and lymphoproliferative disorders. Despite being discovered less than half a century ago, antibiotic resistance, exacerbated by medication non-adherence and inefficacy of proton pump inhibitors, has grown substantially, explaining the rising incidence of refractory H. pylori infection. In this review, we discuss risk factors, treatment options, surveillance and follow-up, as well as emerging therapies for refractory H. pylori.

Real-time PCR detection of Helicobacter pylori clarithromycin resistance in Thrace, Greece

BACKGROUND

Growing resistance to clarithromycin is a major concern regarding treating Helicobacter pylori (H. pylori) infection. Resistance rates have a great variation even in different geographic areas within the same country and are associated with point mutations of the microbial 23S rRNA (A2142C, A2142G, and A2143G). Given the absence of available data in Thrace, the objective of this study was to estimate the resistance of H. pylori to clarithromycin and identify specific mutations that contribute to clarithromycin resistance.

METHODS

In this prospective study, we enrolled consecutive patients referred for dyspeptic complaints who underwent upper gastrointestinal endoscopy over two years. Gastric biopsies from corpus and antrum were initially tested for the presence of urease by a rapid urease test. Urease positive samples were followed by real-time PCR to confirm the presence of H. pylori and to detect point mutations.

RESULTS

A total of one hundred and thirty patients were included in the study (72 women and 58 men). Resistance to clarithromycin was detected at 23.2 %. Neither gender nor age was independently correlated with resistance rate in our patient group. The most common mutations were A2142G and A2143G.

CONCLUSIONS

A high rate of H. pylori resistance to clarithromycin was observed in our region, implicating that it should be addressed in accordance with the recommendations provided by national and international guidelines. Molecular testing should be considered an integral tool for effective monitoring in case of suspected antibiotic resistance. HIPPOKRATIA 2021, 25 (2):51-55.