Numerous risk factors for Helicobacter pylori antibiotic resistance revealed by extended anamnesis: a Bulgarian study

Antimicrobial resistance pattern of Helicobacter pylori in patients evaluated for dyspeptic symptoms in North-Eastern India with focus on detection of clarithromycin resistance conferring point mutations A2143G and A2142G within bacterial 23S rRNA gene

PURPOSE

In India there is evidence of antimicrobial resistance in Helicobacter pylori, a definitive pathobiont whose only known niche is human gastric mucosa. This in turn can lead to failure of treatment, persistence or chronicity of infection. This hospital based, prospective, observational study investigates the presence of antimicrobial resistance in the organism with focus on detection of A2143G and A2142G major point mutations in domain V of H. pylori 23S rRNA gene as a molecular mechanism of conferring resistance.

METHODS

Endoscopic gastric biopsy samples from 52 patients presenting with dyspeptic symptoms from January 2016 to December 2016 were subjected to culture in a microaerophilic environment using Campylobacter agar with for 2-5 days. Isolates were identified using gram-staining, motility test and biochemical reactions. Modified Kirby-Bauer Disc diffusion method was used to determine antimicrobial susceptibility against Clarithromycin, Metronidazole, Amoxycillin, Levofloxacin, Tetracycline, Cotrimoxazole and Erythromycin. Additionally, detection of A2143G and A2142G point mutations conferring Clarithromycin resistance was carried out using real time PCR following extraction and quantification of bacterial DNA. Histopathological examination was carried out on all biopsy samples. Descriptive and inferential statistical analytical methods were used. Differences were considered significant for p < 0.05.

RESULTS

Culture positivity for H. pylori by phenotypic method was found to be 36.54%. Histopathologic Examination detected H. pylori in 55.7% and PCR detected 48.08% for either the wild type or one of two mutant strains A2143G and A2142G. No sample was found positive for both mutations. Metronidazole showed the highest resistance among antibiotics (78.9%) followed by Clarithromycin (47.3%).

CONCLUSION

Prevalence of antimicrobial resistance in H. pylori in North-Eastern India is substantially high with A2143G mutation being clinically most important in conferring Clarithromycin resistance. This resistance might be associated with low eradication rates despite initiation of therapy. ROC analysis of PCR proved it to be a good diagnostic tool.

Increased risk of hearing loss associated with macrolide use: a systematic review and meta-analysis

The increased risk of hearing loss with macrolides remains controversial. We aimed to systematically review and meta-analyze data on the clinical risk of hearing loss, tinnitus, and ototoxicity following macrolide use. A systematic search was conducted across PubMed, MEDLINE, Cochrane, and Embase databases from database inception to May 2023. Medical Subject Heading (MeSH) terms and text keywords were utilized, without any language restrictions. In addition to the electronic databases, two authors manually and independently searched for relevant studies in the US and European clinical trial registries and Google Scholar. Studies that involved (1) patients who had hearing loss, tinnitus, or ototoxicity after macrolide use, (2) intervention of use of macrolides such as azithromycin, clarithromycin, erythromycin, fidaxomicin, roxithromycin, spiramycin, and/or telithromycin, (3) comparisons with specified placebos or other antibiotics, (4) outcomes measured as odds ratio (OR), relative risk (RR), hazard ratio (HR), and mean difference for ototoxicity symptoms using randomized control trial (RCT)s and observational studies (case-control, cross-section, and cohort studies) were included. Data extraction was performed independently by two extractors, and a crosscheck was performed to identify any errors. ORs along with their corresponding 95% confidence intervals (CIs) were estimated using random-effects models. The Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guidelines for RCTs and Meta-Analysis of Observational Studies in Epidemiology guidelines for observational studies were followed. We assessed the hearing loss risk after macrolide use versus controls (placebos and other antibiotics). Based on data from 13 studies including 1,142,021 patients (n = 267,546 for macrolide and n = 875,089 for controls), the overall pooled OR was 1.25 (95% CI 1.07-1.47). In subgroup analysis by study design, the ORs were 1.37 (95% CI 1.08-1.73) for RCTs and 1.33 (95% CI 1.24-1.43) for case-control studies, indicating that RCT and case-control study designs showed a statistically significant higher risk of hearing loss. The group with underlying diseases such as multiple infectious etiologies (OR, 1.16 [95% CI 0.96-1.41]) had a statistically significant lower risk than the group without (OR, 1.53 [95% CI 1.38-1.70] P = .013). The findings from this systematic review and meta-analysis suggest that macrolide antibiotics increase the risk of hearing loss and that healthcare professionals should carefully consider this factor while prescribing macrolides.

Epidemiology of Helicobacter pylori Resistance to Antibiotics (A Narrative Review)

Helicobacter pylori (H. pylori) is the most common bacterial infection worldwide and one of the main etiological factors of chronic gastritis, peptic ulcer disease, and stomach neoplasms. The mass application of antibiotics without testing, especially during the last years of the pandemic of SARS-CoV-2, could lead to a dramatic increase in antibiotic resistance and reduced effectiveness of eradication regimens for H. pylori infection. The epidemiology of H. pylori resistance to antibiotics still has unclear mechanisms. Antibiotic policy should be intensified to optimize treatment, and regular monitoring of resistance of H. pylori in different geographical regions should be conducted. Individualized treatment according to susceptibility testing is strongly advisable, and the best treatment regimens should be selected. The mutations in the genes encoding the antibiotic target protein are significant risk factors for H. pylori resistance. Iatrogenic errors in diagnosis and prescribing treatment for the failure of H. pylori eradication are other important risk factors. The low level of awareness and compliance with the correct treatment influence the rate of H. pylori resistance. Epidemiological surveillance of antibiotic resistance and the adoption of new treatment strategies are needed. The discovery of an efficient vaccine against H. pylori could reduce the pressure of the world's growing antibiotic resistance.

Antibiotic resistance characteristics and risk factors analysis of Helicobacter pylori strains isolated from patients in Liaoning Province, an area in North China

Background

The prevalence of Helicobacter pylori (H. pylori) keeps rising while the eradication rate continues to decline due to the increasing antibiotic resistance. Regional variations of antimicrobial resistance to H. pylori have been recommended by guidelines in recent years. This study aims to investigate the antibiotic resistance rate of H. pylori and its association with infected subjects' characteristics in Liaoning Province, an area in north China.

Methods

Gastric tissues from 178 H. pylori positive participants without previous antibiotic use within four weeks were collected for H. pylori culture. Antibiotic susceptibility to furazolidone (AOZ), tetracycline (TC), levofloxacin (LFX), metronidazole (MET), clarithromycin (CLA), and amoxicillin (AMX) were examined with the agar dilution method. Associations between H. pylori resistance and patient characteristics were further analysed.

Results

No resistance was observed in AOZ or TC. For LFX, MET, CLA, and AMX, the overall resistance rates were 41.10%, 79.14%, 71.78%, and 22.09% respectively. There were significant differences between resistance to CLA and MALToma (P = 0.021), and between resistance to MET and age (P < 0.001).

Conclusions

The primary resistant rates of LEX, MET, CLA, and AMX were relatively high in Liaoning. Treatment effectiveness improvement could be achieved by prior antimicrobial susceptibility tests before antibiotic prescription.

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.

High prevalence and risk factors of multiple antibiotic resistance in patients who fail first-line Helicobacter pylori therapy in southern China: a municipality-wide, multicentre, prospective cohort study

BACKGROUND

We aimed to study the prevalence of secondary antibiotic resistance of Helicobacter pylori in southern China and its risk factors, particularly geographical and socio-economic factors.

METHODS

This was a municipality-wide, multicentre, prospective cohort study involving five major hospitals. Patients aged ≥18 years who failed first-line bismuth-based quadruple anti-H. pylori therapy between September 2016 and February 2018 were recruited. Participants underwent upper gastrointestinal endoscopy with biopsy from the antrum and body for H. pylori culture and antimicrobial susceptibility testing for six antibiotics (clarithromycin, levofloxacin, metronidazole, amoxicillin, tetracycline and furazolidone). Patients with failure of H. pylori culture were excluded. Participants completed a questionnaire profiling 22 potential risk factors of H. pylori infection and antibiotic resistance, including medical, social, household and birthplace factors.

RESULTS

A total of 1113 patients failed first-line therapy, with successful H. pylori culture in 791 (71.1%) [male = 433 (54.7%); median age = 43 years]. Secondary resistance rates of dual antibiotics (clarithromycin + metronidazole and levofloxacin + metronidazole) and triple antibiotics (clarithromycin + levofloxacin + metronidazole) were 34.0%, 38.7% and 17.8%, respectively. Risk factors for clarithromycin + metronidazole resistance were history of ≥2 courses of H. pylori therapies [adjusted OR (aOR) = 1.71; 95% CI = 1.17-2.54], ≥3 household members (aOR = 2.00; 95% CI = 1.07-3.90) and family history of gastric cancer (aOR = 1.85; 95% CI = 1.18-2.85). Risk factors for levofloxacin + metronidazole resistance were age ≥40 years (aOR = 1.94; 95% CI = 1.37-2.75), lower gross domestic product per capita (aOR = 0.29; 95% CI = 0.10-0.80) and higher number of doctors/10 000 population (aOR = 1.59; 95% CI = 1.07-2.39). A higher human development index was of borderline significance (aOR = 2.79; 95% CI = 0.97-8.70).

CONCLUSIONS

The rates of secondary resistance of H. pylori to multiple antibiotics were high in southern China. Certain population-level risk factors were associated with levofloxacin + metronidazole resistance.

Antibiotic resistance pattern and frequency of cagA and vacA genes in Helicobacter pylori strains isolated from patients in Tabriz city, Iran

Objective

Helicobacter pylori is one of the most common causes of gastric infections in humans. It is estimated that approximately 50% of people around the world are infected with this bacterium. This study aimed to determine the antibiotic resistance pattern, as well as the frequency of cagA and vacA genes in H. pylori isolates obtained from patients in the clinical centers in Tabriz city, Iran.

Results

The culture method detected 100 (45.25%) H. pylori isolates from 221 biopsy samples during 3 years. The results showed that 63% and 81% of the isolates were positive for cagA and vacA genes, respectively. The highest resistance of isolates was seen against metronidazole (79%) and amoxicillin (36%), respectively. Also, the isolates showed the least resistance to tetracycline (8%).

Correlation Analysis Among Genotype Resistance, Phenotype Resistance and Eradication Effect of Helicobacter pylori

Background

It has not been fully confirmed whether the detection of Helicobacter pylori resistance gene mutation can replace antibiotic drug sensitivity test to guide the clinical individualized treatment. Therefore, we have studied this aspect and discussed the application value of antibiotic sensitivity gene test.

Materials and Methods

The biopsy specimen of gastric mucosa from the patients examined by endoscopy and positive for rapid urease test were collected continuously for histopathological analysis, H. pylori culture, antibiotic drug sensitivity test (E-test drug sensitivity test), and antibiotic sensitivity gene test (high-throughput nucleotide sequencing). The participants received triple plus bismuth solution eradication treatment (esomeprazole 20 mg, amoxicillin 1000 mg, clarithromycin 500 mg, and bismuth potassium citrate 220 mg, twice daily for 14 days) for follow-up, and the eradication effect was determined.

Results

The 551/602 subjects, who met the inclusion criteria, were subjected to culture for H. pylori and antibiotic drug sensitivity determination; among them 506 were cultured successfully. The results showed that the resistance rates of H. pylori were 38.9% for clarithromycin and 31.0% for levofloxacin. In 489 H. pylori strains, the mutations were detected in clarithromycin and levofloxacin resistance genes, indicating the genotype resistance. The resistance genes of clarithromycin and levofloxacin were consistent with phenotype resistance with respect to sensitivity (81.2% and 69.7% for clarithromycin and levofloxacin, respectively) and specificity (88.9% and 93.7% for clarithromycin and levofloxacin, respectively). The eradication rate of H. pylori in the clarithromycin-resistant group was significantly lower than that in the sensitive group (ITT: 52.1% vs 85.0%, P < 0.001).

Conclusion

A correlation was established between the resistance genes of clarithromycin and levofloxacin and their phenotypic resistance and clinical efficacy. The detection of H. pylori resistance genes has a good clinical application prospect.

[Antibiotic resistance of Helicobacter pylori in the European part of the Russian Federation: first results]

AIM

Determine the primary antibiotic resistance of Helicobacter pylori (H. pylori) strains isolated from patients living in the European part of the Russian Federation.

MATERIALS AND METHODS

As part of a clinical laboratory study, from 2015 to 2018, 27 gastrobiopsy samples obtained from H. pylori-infected patients were analyzed. H. pylori infection was verified using a rapid urease test or a 13C-urea breath test. The values of the minimum inhibitory concentration (MIC) of antibiotics were determined by the diffusion method using E-test strips (BioMerieux, France) according to the recommendations of the manufacturer. The sensitivity of the isolates was determined for 6 antibacterial drugs (amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, rifampicin).

RESULTS

According to the data obtained, resistance to amoxicillin was 0%, clarithromycin 11.1%, metronidazole 59.3%, levofloxacin 3.7%, tetracycline 0%, and rifampicin 14.8%. Dual resistance to clarithromycin and metronidazole was recorded in two isolates (7.4%).

CONCLUSION

Thus, the first results of the evaluation of H. pylori antibiotic resistance in the European part of the Russian Federation indicate a low resistance of the microorganism to clarithromycin and quite high to metronidazole.

High Primary Antibiotic Resistance of Helicobacter pylori Strains Isolated from Pediatric and Adult Patients in Poland during 2016-2018

Monitoring the antibiotic resistance of H. pylori is an important step in the effective treatment of this bacterium, thus the aim of the present study was to assess the prevalence of antimicrobial resistance of H. pylori strains isolated from pediatric and adult patients with primary infections in 2016–2018. Antral biopsies from 334 treatment-naïve patients (126 children and 208 adults) were obtained. A total of 71 clinical H. pylori strains (22 from children and 49 from adults) were isolated and examined for amoxicillin (AMX), clarithromycin (CLR), metronidazole (MTZ), tetracycline (TET), and levofloxacin (LEV) susceptibility. The activity of the antibiotics was measured by E-tests. Strains were considered as resistant to antibiotics with minimum inhibitory concentrations (MICs) equal to ≥0.125 μg/mL (AMX), ≥0.5 μg/mL (CLR), ≥8 μg/mL (MTZ), and ≥1 μg/mL (TET and LEV). The highest prevalence of antibiotic resistance in H. pylori strains was observed for CLR and MTZ, at frequencies of 54.5% and 31.8% vs. 30.6% and 46.9% for children and adults, respectively. A much lower frequency of isolation of resistant strains was demonstrated for LEV and TET, this being 9.1% and 4.5% vs. 18.4% and 4.1% for pediatric and adult patients, respectively. The presence of AMX-resistant strains was not observed. The H. pylori strains isolated from Polish patients with primary infections showed a high level of antibiotic resistance to CLR and MTZ (>30%).

Sociodemographic characteristics and clinical risk factors of Helicobacter pylori infection and antibiotic resistance in the Eastern Black Sea region of Turkey

BACKGROUND/AIMS

The aim of this study was to assess the clinical and sociodemographic risk factors of Helicobacter pylori infection and antibiotic resistance in the eastern Black Sea region of Turkey.

MATERIALS AND METHODS

In total, 344 patients with dyspeptic symptoms who completed an extended questionnaire were enrolled in the study. Diagnosis of H. pylori infection was made by rapid urease test, histopathological investigation, and culture. Susceptibility of H. pylori strains was assessed by agar dilution (amoxicillin, tetracycline, metronidazole, levofloxacin) and E-test (clarithromycin) methods.

RESULTS

The H. pylori positivity rate was 40.4% (139/344). Logistic regression analysis indicated that age and the presence of duodenal ulcer were independent risk factors associated with H. pylori positivity (odds ratio (OR): 0.96, 95% CI: 0.93-0.99, p=0.013; OR: 5.42, 95% CI: 1.96-14.98, p=0.001, respectively). Of 104 H. pylori-positive cultures, 43 strains (41%) were susceptible to all antibiotics, whereas 61 (59%) were resistant to at least one antibiotic. H. pylori resistance rates were 34% for levofloxacin, 31.1% for metronidazole, 28.2% for clarithromycin, 2.9% for amoxicillin, and 1% for tetracycline. Logistic regression analysis indicated that previous use of clarithromycin was the only independent risk factor for H. pylori resistance (OR: 6.25, 95% CI: 1.59-24.52, p=0.009).

CONCLUSION

An understanding of the risk factors for H. pylori positivity and antibiotic resistance in an extended anamnesis may affect treatment choice and facilitate H. pylori eradication. In regions where antibiotic resistance rates are elevated, performing antibiotic susceptibility tests may lead to effective eradication treatment.

Primary antimicrobial resistance rates and prevalence of Helicobacter pylori infection in the north of Spain. A 13-year retrospective study

OBJECTIVE

Helicobacter pylori resistance to antimicrobial agents is on the rise and it is thus imperative to be aware of local resistance rates. The main objective of the present study was to describe the evolution of primary antimicrobial resistance in H. pylori, analysing its antibiotic susceptibility over a 13-year period in a region of northern Spain, as well as host-related factors.

PATIENTS AND METHODS

Between 2004 and 2016 a total of 3426 patients who met the H. pylori eradication criteria underwent gastroscopy. The gastric biopsies were processed and those testing positive for H. pylori were identified and tested for clarithromycin, metronidazole and levofloxacin susceptibility using E-test.

RESULTS

H. pylori was isolated in 1604 (47%) patients, ranging from 63% (133/212) in 2004 to 39% (137/347) in 2016. Primary resistances to clarithromycin, metronidazole and levofloxacin were on average 19% (278/1116), 40% (572/865) and 17% (137/669), respectively. Clarithromycin resistance was 24% (167/686) in females and 15% (11/753) in males (p=0.0002); metronidazole resistance was 29% (72/246) in patients over 70 years compared to 42% (499/1190) in younger patients (p=0.0396); levofloxacin resistance increased with age, being 13% (57/439) in patients ≤55 years, 19% (46/236) for those between 56 and 70, and 26% (34/130) in patients >70 years (p=0.0087).

DISCUSSION

A decline in the prevalence of H. pylori infection was observed over the years, along with relatively high rates of primary resistance to clarithromycin, metronidazole and levofloxacin. Variations in resistance rates were found with sex and age.

Antibiotic dispensation rates among participants in community-driven health research projects in Arctic Canada

Background

Community-driven projects that aim to address public concerns about health risks from H. pylori infection in Indigenous Arctic communities (estimated H. pylori prevalence = 64%) show frequent failure of treatment to eliminate the bacterium. Among project participants, treatment effectiveness is reduced by antibiotic resistance of infecting H. pylori strains, which in turn, is associated with frequent exposure to antibiotics used to treat other infections. This analysis compares antibiotic dispensation rates in Canadian Arctic communities to rates in urban and rural populations in Alberta, a southern Canadian province.

Methods

Project staff collected antibiotic exposure histories for 297 participants enrolled during 2007–2012 in Aklavik, Tuktoyaktuk, and Fort McPherson in the Northwest Territories, and Old Crow, Yukon. Medical chart reviews collected data on systemic antibiotic dispensations for the 5-year period before enrolment for each participant. Antibiotic dispensation data for urban Edmonton, Alberta (average population ~ 860,000) and rural northern Alberta (average population ~ 450,000) during 2010–2013 were obtained from the Alberta Government Interactive Health Data Application.

Results

Antibiotic dispensation rates, estimated as dispensations/person-years (95% confidence interval) were: in Arctic communities, 0.89 (0.84, 0.94); in Edmonton, 0.55 (0.55, 0.56); in rural northern Alberta, 0.63 (0.62, 0.63). Antibiotic dispensation rates were higher in women and older age groups in all regions. In all regions, the highest dispensation rates occurred for β-lactam and macrolide antibiotic classes.

Conclusions

These results show more frequent antibiotic dispensation in Arctic communities relative to an urban and rural southern Canadian population.

The antibiotic resistance of Helicobacter pylori to five antibiotics and influencing factors in an area of China with a high risk of gastric cancer

Background

H. pylori exhibits antibiotic resistance with regional differences. In this paper, we explored antibiotic resistance of H. pylori to five antibiotics in an area with a high risk of gastric cancer.

Results

H. pylori resistance rates to metronidazole, levofloxacin, clarithromycin, amoxicillin, and tetracycline were 78.0, 56.0, 31.0, 9.0, and 15.0%, respectively. Double, triple, quadruple, and quintuple resistance rates were 23, 20, 6, and 4%, respectively. The clarithromycin and multidrug resistance rates were significantly higher in males than females (clarithromycin: 44.4% vs 15.2%, respectively, P = 0.002; multidrug: 75.5% vs 37.2%, respectively; P < 0.001). During the three periods of 1998–1999, 2002–2004 and 2016–2017, the resistance rates to levofloxacin and amoxicillin were increasing (OR: 2.089, 95%CI: 1.142–3.821, P = 0.017; and OR: 5.035, 95%CI: 1.327–19.105, P = 0.018, respectively). The antibiotic resistance rates were unassociated with the host disease state. Metronidazole resistance was lower in the vacAs1m1/m2 group than the vacAs1m1m2 group (65% vs 85.7%, respectively; P = 0.026). As for levofloxacin resistance, it was higher with cagA⁺ than cagA⁻ (60.9% vs 23.1%, respectively; P = 0.020) but lower with slyD⁺ than slyD⁻ (41.4% vs 68.5%, respectively; P = 0.009). Clarithromycin had a lower resistance rate with iceA⁺⁺ than iceA⁻⁺ (19.7% vs 52.4%, respectively; P = 0.017). For amoxicillin, the iceA⁺⁺ group had a lower resistance rate than the iceA⁻⁻ group (1.6% vs 27.8%, respectively; P = 0.009).

Conclusions

The total resistance rates of H. pylori to metronidazole, levofloxacin, clarithromycin, amoxicillin, and tetracycline were high in Zhuanghe. The resistanc rates to levofloxacin and amoxicillin increased over time. Clarithromycin resistance was associated with male and iceA. The resistance of metronidazole was related to vacA. Levofloxacin resistance was concerned with cagA and slyD and amoxicillin resistance was concerned with iceA. While, the antibiotic resistance of H. pylori had nothing to do with the status of gastric disease.

Prevalence of Primary Resistance of Helicobacter pylori to Clarithromycin and Levofloxacin in Southern Spain

BACKGROUND

The eradication of Helicobacter pylori (HP) using clarithromycin (CLA)-based triple therapy depends on the resistance of HP to antibiotics. The Maastricht III conference recommends the implementation of locoregional surveillance programmes for primary resistance of HP to CLA. In Andalusia, there are no previous data in this respect. The aim of this study was to determine the prevalence of the primary resistance of HP to CLA and levofloxacin (LF) in southern Spain.

METHODS

Multicentre cross sectional study was carried out in 6 hospitals in Andalusia. Patients of both sexes numbering 401 were included (male 48%), aged 18-80 years and naïve to HP eradication. Resistance of HP to CLA (CLAr) and LF (LFr) was assessed by determining mutations by PCR: mutations of the 23S rRNA gene define CLAr and mutations of the gene gyrA define LFr. Four hundred one gastric samples were collected. CLAr was detected in 72 patients (17.9%) and LFr was detected in 56 patients (13.9%). Heteroresistance was detected for both antibiotics: CLA 37/72 (51.3%) and LF 28/56 (50%). Variability for CLAr was detected among the centres, ranging from 11.5% to 24.7% without statistical significance (p = 0.12). Female sex was related to CLAr.

CONCLUSIONS

In Andalusia, there is a high rate of primary CLAr and LFr. CLA-based triple therapy should be avoided as the primary eradication regimen in this region. There is a wide variability in the rate of CLAr among centres.

[Molecular genetic predictors of resistance to anti-Helicobacter pylori therapy]

In current clinical practice, there is no optimal empirical therapy for Helicobacter pylori (H. pylori) infection and there is a progressive decrease in the efficiency of classical eradication therapy (ET) regimens. The variability in the efficiency of ET in a specific patient is largely due to the heterogeneous molecular genetic mechanisms underlying the resistance of the microorganism to the components of the treatment regimens. The basis of the mechanisms for antibiotic resistance in H. pylori is mainly the point mutations in some genes, which determine alterations in the mechanisms of action of drugs, such as clarithromycin (domain V of 23S rRNA), metronidazole (rdxA, frxA), amoxicillin (pbp1A), tetracycline (16S rRNA), and levofloxacin (gyrA). The predictors of resistance to ET are also the CagA-negative status of the microorganism and the presence of the vacA s2 allele. There are a number of host genetic determinants (the CYP2C19 genotype (*1/*1, *1/*17, *17/*17) and the MDR1 3435 T/T genotype (in an Asian population)) that reduce the efficiency of ET, by altering the pharmacokinetics of proton pump inhibitors. In addition, the IL-1β-511 C/C polymorphism that affects gastric acid secretion is a predictor of the inefficiency of ET.

Prevalence of antibiotic resistance in Helicobacter pylori: A recent literature review

AIM: To review previous studies (the last 6 years) about the Helicobacter pylori (H. pylori) antibiotic resistance in order to evaluate the trend in antibiotic resistance.

METHODS: In this study, the PubMed, MEDLINE, Science Direct, Google Scholar and Scielo manuscripts were reviewed from 2009 to 2014.

RESULTS: On the whole rates of H. pylori antibiotic resistance were 47.22% (30.5%-75.02%) for metronidazole, 19.74% (5.46%-30.8%) for clarithromycin, 18.94% (14.19%-25.28%) for levofloxacin, and 14.67% (2%-40.87%) for amoxicillin, 11.70% (0%-50%) for tetracycline, 11.5% (0%-23%) for furazolidon and 6.75% (1%-12.45%) for rifabutin. The frequency of tetracycline, metronidazole and amoxicillin resistance was higher in Africa, while clarithromycin and levofloxacin resistance was higher in North America and Asian, respectively.

CONCLUSION: The most sensitive drug is rifabutin and the lowest sensitive drug is metronidazole in the world. The worldwide H. pylori antibiotic resistance to clarithromycin and levofloxacin has increased during the last 6 years. The present systematic review show alarming results and a novel plan is needed for eradication therapy of H. pylori infections.

Treatment of Helicobacter pylori infection: Past, present and future

Helicobacter pylori (H. pylori) is a major human pathogen associated with significant morbidity and mortality. However, after decades of efforts, treatment of H. pylori remains a challenge for physicians, as there is no universally effective regimen. Due to the rising prevalence of antimicrobial resistance, mainly to clarithromycin, efficacy of standard triple therapies has declined to unacceptably low levels in most parts of the world. Novel regimens, specifically experimented to improve the therapeutic outcome against antibiotic-resistant H. pylori strains, are now recommended as first-line empirical treatment options providing high efficacy (reportedly > 90% in intention to treat analysis) even in high clarithromycin resistance settings. These include the bismuth quadruple, concomitant, sequential and hybrid therapies. Due to the rapid development of quinolone resistance, levofloxacin-based regimens should be reserved as second-line/rescue options. Adjunct use of probiotics has been proposed in order to boost eradication rates and decrease occurrence of treatment-related side effects. Molecular testing methods are currently available for the characterization of H. pylori therapeutic susceptibility, including genotypic detection of macrolide resistance and evaluation of the cytochrome P450 2C19 status known to affect the metabolism of proton pump inhibitors. In the future, use of these techniques may allow for culture-free, non-invasive tailoring of therapy for H. pylori infection.

Treatment of Helicobacter pylori infection: meeting the challenge of antimicrobial resistance

Treatment of Helicobacter pylori (H. pylori) infection is paramount for the management of prevalent gastrointestinal disorders including peptic ulcer disease and gastric cancer. Due to the wide increase in prevalence of H. pylori resistance to antibiotics, clarithromycin-based triple therapies are not any more suitable for unconditional empiric use, and should not be recommended, unless local resistance to this antibiotic is low (< 20%). Alternative strategies have been proposed to overcome the issue of increasing clarithromycin resistance, and some of them are already implemented in clinical practice. These comprise: (1) adoption of novel, more effective, empirical treatments: bismuth quadruple, sequential, non-bismuth quadruple (concomitant), dual-concomitant (hybrid), and levofloxacin-based regimens, the latter mainly designated as second-line/rescue options; (2) perspectives for a susceptibility-guided (tailored) therapeutic approach based on culture-free molecular testing methods; and (3) adjunct use of probiotics to improve eradication rates. The present article is aimed to provide a comprehensive overview of current and emerging strategies in the treatment of H. pylori infection, focusing on the challenge of antimicrobial resistance.

Prospective multicentre study on antimicrobial resistance of Helicobacter pylori in Germany

OBJECTIVES

Antimicrobial resistance of Helicobacter pylori endangers the successful eradication of the bacteria. The aim of this prospective surveillance study (ResiNet) is to continuously keep antimicrobial resistance of H. pylori in Germany under surveillance and to identify risk factors for its development.

METHODS

From July 2001 until December 2012, we tested the antimicrobial susceptibility of H. pylori strains isolated from 1651 prospectively enrolled patients. We analysed clinical and epidemiological data and identified risk factors for the development of resistance.

RESULTS

Average primary resistances were 29.4% for metronidazole, 6.7% for clarithromycin and 3.1% for both antimicrobials. Prior unsuccessful eradication treatments, female sex and country or continent of origin were identified as independent risk factors for development of resistance.

CONCLUSIONS

H. pylori-positive patients without prior eradication therapy can be treated empirically; antimicrobial susceptibility testing is recommended in previously unsuccessfully treated patients and in patients who have received antimicrobial chemotherapies due to unrelated bacterial infections.

Antibiotics resistance rate of Helicobacter pylori in Bhutan

AIM: To survey the antibiotic resistance pattern of Helicobacter pylori (H. pylori) strains isolated from Bhutanese population.

METHODS: We isolated 111 H. pylori strains from the gastric mucosa of H. pylori-infected patients in Bhutan in 2010. The Epsilometer test was used to determine the minimum inhibitory concentrations (MICs) of amoxicillin (AMX), clarithromycin (CLR), metronidazole (MNZ), levofloxacin (LVX), ciprofloxacin (CIP), and tetracycline (TET).

RESULTS: Nineteen of the isolated H. pylori strains were susceptible to all antibiotics tested. The isolated strains showed the highest rate of antibiotic resistance to MNZ (92/111, 82.9%). Among the 92 MNZ-resistant strains, 74 strains (80.4%) showed high-level resistance (MIC ≥ 256 μg/mL). Three strains were resistance to LVX (2.7%). These strains were also resistance to CIP. None of the strains showed resistance to CLR, AMX and TET.

CONCLUSION: CLR-based triple therapy is a more effective treatment approach over MNZ-based triple therapy for H. pylori infection in Bhutan.

Primary clarithromycin resistance to Helicobacter pylori: Is this the main reason for triple therapy failure?

Conventional triple therapies for Helicobacter pylori (H. pylori) eradication have recently shown a disappointing reduction in effectiveness in many countries. The main reason for failure was found to be bacterial resistance to one of the most commonly used antibiotics, clarithromycin. An additional problem for conventional triple therapy is the high rate of resistance to metronidazole found in Europe, America and Asia. In Italy, in the last 15 years a 2-fold increase in resistance has occurred. A recent study of the whole of Italy included about 20 patients from each region at the first endoscopic diagnosis of H. pylori infection. The most surprising result was the patchy distribution of resistance, which was almost absent in two regions (one northern and one southern), although the highest prevalence was found in some regions of the South. In the paediatric population we found a 25% prevalence of resistance in a sample of H. pylori positive children observed between 2002 and 2007, mirroring data obtained in southern European countries. Clarithromycin resistance assessment is currently based on phenotypic detection performed after culture the agar dilution method or E-test, and genotypic methods based on polymerase chain reaction (PCR). In a recent comparative study we found a 71.2% agreement between the two methods. Culture-free techniques are highly accurate in finding even minimal traces of genotypically resistant strains. Moreover, PCR-based tools are accurate in detecting a heteroresistant status, defined as the co-existence of some strains that are susceptible and some resistant to the same antibiotic in an individual patient. Three point mutations, namely A2143G, A2142G and A2142C, are responsible for 90% of cases of primary clarithromycin resistance in H. pylori strains isolated in Western countries, although we previously demonstrated that the presence of the A2143G mutation, but not A2142G or A2142C, significantly lowered the H. pylori eradication rate. Treatment failure has considerable cost/benefit implications because of “waste” of National Health System and patient resources, in terms of drugs, further diagnostic tests and medical examination expenses. Therefore, in future it would be very useful to be able to test for clarithromycin resistance before starting conventional triple therapy. Hopefully, fast, effective non-invasive tests may soon be devised to determine this condition.

The incidence of primary antibiotic resistance of Helicobacter pylori in Vietnam

GOALS

To determine the susceptibility of Helicobacter pylori strains isolated from a Vietnamese population to 5 antibiotics.

BACKGROUND

The incidence of antibiotic resistance in H. pylori infection is increasing worldwide and has become a leading cause for failure of treatment. Antibiotic susceptibility testing is very important to provide optimal regimens in a clinical setting.

STUDY

We isolated 103 H. pylori strains from the gastric mucosa of H. pylori-infected patients from 2 areas in Vietnam (Ho Chi Minh and Hanoi) in 2008. Epsilometer test was used to determine the minimum inhibitory concentrations of amoxicillin, clarithromycin (CLR), metronidazole (MNZ), levofloxacin, and tetracycline.

RESULTS

Among the 103 strains, the resistance rates were 0% (amoxicillin), 33% (CLR), 69.9% (MNZ), 18.4% (levofloxacin), and 5.8% (tetracycline). The resistant strains showed a high-level of resistance (≥ 256 µg/mL) to CLR, 23.5% (8/34), and MNZ, 29.1% (21/72). The resistance rate for CLR was significantly higher in Ho Chi Minh than in Hanoi (49% vs. 18.5%, P=0.001). Resistance to both CLR and MNZ was most commonly observed (24.3%). Two strains (1.9%) were resistant to 4 of the 5 antibiotics. No significant association was observed between antibiotic resistance rates and age, sex, or clinical outcomes of the patients.

CONCLUSIONS

High incidence of resistance to CLR and MNZ suggests that standard triple therapies may not be useful as first-line treatment in Vietnam. Alternative strategies such as bismuth-based quadruple therapies or sequential therapy may be more effective in Vietnam.

Comparative in vitro antimicrobial susceptibility and synergistic activity of antimicrobial combinations against Helicobacter pylori isolates in Taiwan

BACKGROUND

Antimicrobial resistance is a major determinant of Helicobacter pylori treatment failures. We conducted a population-based survey to monitor changing antimicrobial susceptibility of H. pylori isolates in Taiwan, with a focus on combinatorial effects of synergism and the influence of acidity.

METHODS

H. pylori isolates from endoscopic specimens taken from patients enrolled at two medical centers were obtained between January 2008 and December 2009. Minimum inhibitory concentrations (MICs) were determined by agar dilution and Etest methods. Agar media of varying pH (pH 7.3, 6.0, or 5.0) were used to assess whether acidity influences the bactericidal effects of the agents tested. Time-kill assays were used to assess for synergism between different drug combinations.

RESULTS

A total of 176 non-duplicate H. pylori isolates from endoscopic specimens were tested. The following MIC90 (mg/L) (susceptible) results were obtained at neutral pH 7.3: amoxicillin, 0.25 (100%); tetracycline, 0.5 (100%); metronidazole, 32 (67.6%); clarithromycin, 0.25 (90.3%); ciprofloxacin, 1 (92.0%); gemifloxacin, 0.5 (94.9%); levofloxacin, 1 (93.2%); and moxifloxacin, 1 (91.5%). A decrease in pH from 6.0 to 5.0 significantly decreased the antimicrobial activity of levofloxacin and moxifloxacin against H. pylori. For clarithromycin-susceptible isolates, levofloxacin combined with clarithromycin provided both synergistic and bactericidal effects. For clarithromycin-resistant isolates with amoxicillin hypersusceptibility (MIC <0.01 mg/L), levofloxacin with amoxicillin or minocycline had at best additive effect but no bactericidal effects.

CONCLUSION

Amoxicillin, tetracycline, clarithromycin, and fluoroquinolones, but not metronidazole, showed good in vitro anti-H. pylori activity (>90% susceptible). Synergism was only observed for clarithromycin-susceptible isolates. Acidity adversely influenced the antimicrobial activity of levofloxacin against H. pylori.

[Helicobacter pylori - 2012]

The author overviews some aspects of literature data of the past 2 years. Genetic research has identified polymorphisms of Helicobacter pylori virulence factors and the host which could play a role in the clinical outcome of the infection (peptic ulcer or gastric cancer). So far they have been performed in research centers but with a decrease of costs, they will take their place in diagnosing the diseases and tailoring the treatment. Antibiotic resistance is still growing in Southern European countries and is decreasing in Belgium and Scandinavia. Currently, the clarithromycin resistance rate is of 17-33% in Budapest and levofloxacin resistance achieved 27%. With careful assessment of former antibiotic use the resistance to certain antibiotics can be avoided and the rates of eradication improved. Immigration is a growing problem worldwide: according to Australian, Canadian and Texan studies, the prevalence of Helicobacter pylori is much higher in the immigrant groups than in the local population. An Italian study showed that the eradication rate of triple therapy is significantly lower in the Eastern European immigrants than in the Italians. A recent research has suggested a link between female/male infertility, habitual abortion and Helicobacter pylori infection. However, there are no published data or personal experience to show whether successful eradication of the virus in these cases is followed by successful pregnancies or not. The author overviews the Maastricht process and analyzes the provisions of the Maastricht IV/Florence consensus, in which the new diagnostic algorithms and indications of eradication therapy are reformulated according to the latest levels of evidence and recommendation grading. According to the "test and treat" strategy, either the urea breath test or the stool monoclonal antigen test are recommended as a non-invasive diagnostic method in primary care. Endoscopy is still recommended in case of alarm symptoms, complicated ulcer, or if there is a suspicion of malignancy or MALT lymphoma. Local resistance to clarithromycin and levofloxacin should be considered in the choice of first-line therapy, in case of levels >15-20% these compounds should not be used. In regions with low resistance rates, classical triple therapy remains the regimen of choice; its alternative is the bismuth-based quadruple therapy. Determining antimicrobial resistance is justified after failed second- or third-line therapies; where available, molecular methods (fluorescence in situ hybridization, polymerase chain reaction) should be used. As second/third line treatments, the sequential, bismuth-based quadruple, concomitant quadruple regimens, hybrid are all possible alternatives. The Hungarian diagnostic and therapeutic approach in practice is different in some aspects from the provisions of the European consensus. Orv. Hetil., 2012, 153, 1407-1418.