Prevalence of multiple drug-resistant Helicobacter pylori strains among patients with different gastric disorders in Iran

Antimicrobial-Resistance Profile of Helicobacter pylori, Obtained from Endoscopic Patients in Bahir Dar, North West Ethiopia

Background

Antimicrobial resistance for Helicobacter pylori infection is a highly emerging problem throughout the world to treat gastric-associated diseases. People living in developing countries are more likely to acquire a Helicobacter pylori infection and less likely to gate treatment after infection due to poverty. Therefore, the current study was aimed at determining the magnitude and antibiotic-resistance profile of Helicobacter pylori isolated from patients who underwent endoscopic examination.

Methods

A cross-sectional study was conducted from January to May 2019 at endoscopy service-providing health facilities that are found in Bahir Dar, Ethiopia (Gamby teaching general hospital, Kidane Mihret specialty higher clinic, and Eyasta specialty higher clinic). Data were collected using a pretested, structured questionnaire. Antibiotic susceptibility of Helicobacter pylori isolates from gastric biopsies was determined. Data were analyzed using SPSS version 23.

Results

The 17.8% proportion of Helicobacter pylori was isolated from 135 endoscopy-examined patients (24/135). The majority of isolates (71% of 17/24) were from males, while only 29% of 7/24) were from females. Antimicrobial-resistance of Helicobacter pylori was high to all commonly prescribed antibiotics: amoxicillin and metronidazole (91.7%), clarithromycin and ciprofloxacin (66.7% each), and tetracycline (37.5%).

Conclusion

Helicobacter pylori isolates from the current study participants were rather low in number. But the highest antibiotic-resistance profile of Helicobacter pylori was observed. Therefore, these findings alarmingly indicate that routine antimicrobial susceptibility testing against Helicobacter pylori isolates is crucial for better patient management.

Optimizing Helicobacter pylori Treatment: An Updated Review of Empirical and Susceptibility Test-Based Treatments

As the rate of discovery of drug-resistant Helicobacter pylori cases increases worldwide, the relevant societies have updated their guidelines for primary eradication regimens. A promising strategy against drug-resistant H. pylori is tailored therapy based on the results of an antibiotic susceptibility test; however, it is difficult to apply this strategy to all cases. Although culture-based antibiotic susceptibility tests can assess resistance to any antimicrobial agent, their greatest disadvantage is the time required to draw a conclusion. In contrast, molecular-based methods, such as polymerase chain reaction, can rapidly determine the presence of resistance, although a single test can only test for one type of antimicrobial agent. Additionally, the limited availability of facilities for molecular-based methods has hindered their widespread use. Therefore, low-cost, minimally invasive, simple, and effective primary regimens are needed. Several studies have compared the efficacy of the latest primary eradication regimens against that of tailored therapies, and their results have shaped guidelines. This article reviews the latest research on empirical and tailored treatments for H. pylori infections. Evidence for the superiority of tailored therapy over empirical therapy is still limited and varies by region and treatment regimen. A network meta-analysis comparing different empirical treatment regimens showed that vonoprazan triple therapy provides a superior eradication effect. Recently, favorable results towards vonoprazan dual therapy have been reported, as it reached eradication levels similar to those of vonoprazan triple therapy. Both vonoprazan dual therapy and tailored therapy based on antibiotic susceptibility tests could contribute to future treatment strategies.

Advances in the pharmacological and regulatory management of multidrug resistant Helicobacter pylori

INTRODUCTION

Antibiotic resistance of Helicobacter pylori (H. pylori) hampers the success of eradication and in recent years multidrug resistance (MDR) shows an increase worldwide.

AREAS COVERED

This review covers current aspects of pharmacological and regulatory management of MDR-resistant H. pylori infection.

EXPERT OPINION

MDR H. pylori is increasing worldwide and its prevalence varies both between continents and countries. High consumption and misuse of antibiotics, H. pylori treatment failures and bacterial factors such as mutations, efflux pumps and biofilms are among the factors associated with MDR. Important steps for confronting the rise of MDR H. pylori strains should follow the principles of antibiotic stewardship, i.e. eradication regimens should be optimized with regard to all aspects of therapy, including drugs, doses, formulation, frequency of administration, administration in relation to meals and duration of therapy that reliably achieve at least 90% (preferably >95%) cure rates in adherent patients with susceptible infections.

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.

The increasing antimicrobial resistance of Helicobacter pylori in Iran: A systematic review and meta-analysis

BACKGROUND

Antimicrobial resistance of Helicobacter pylori can result in eradication failure. Metadata on the antimicrobial resistance of H pylori in Iran could help to formulate H pylori eradication strategies in Iran.

METHODS

A systematic review was performed after searching in MEDLINE, Scopus, Embase, Web of Science, and the Cochrane Library. A meta-analysis was performed, and a comparison of the rates between children and adults; time periods (1999-2010, 2011-2016, 2017-2019); and the methods used was carried out.

RESULTS

A total of 66 studies investigating 5936 H pylori isolates were analyzed. The weighted pooled resistance (WPR) rates were as follows: clarithromycin 21% (95% CI 16-26), metronidazole 62% (95% 57-67), clarithromycin in combination with metronidazole 16% (95% CI 10-23), ciprofloxacin 24% (95% CI 15-33), levofloxacin 18% (95% CI 9-30), erythromycin 29% (95% CI 12-50), furazolidone 13% (95% CI 4-27), tetracycline 8% (95% CI 5-13), and amoxicillin 15% (95% CI 9-22). During the three time periods, there was an increased resistance to amoxicillin, clarithromycin, ciprofloxacin, furazolidone, and tetracycline (P ˂ .05). Furazolidone and a clarithromycin/metronidazole combination had the higher resistance rates in children (P ˂ .05).

CONCLUSION

An increasing rate of resistance to amoxicillin, clarithromycin, ciprofloxacin, furazolidone, and tetracycline in Iranian H pylori isolates was identified. In children, the resistance to furazolidone and a combination of clarithromycin and metronidazole is higher compared to adults. As a stable, high resistance to metronidazole was found in children and adults in all Iranian provinces, we suggest that metronidazole should not be included in the Iranian H pylori eradication scheme.

Management of antibiotic-resistant Helicobacter pylori infection: current perspective in Iran

Helicobacter pylori is a common gastric bacterial pathogen implicated in the pathogenesis of many digestive tract disorders. H. pylori infection prevalence has been reported alarmingly in Iran. A plethora of studies have been conducted to evaluate the efficiency of first-line and second-line eradication attempts in patients diagnosed with H. pylori infections in Iran. The present study, was evaluated the efficacy of first-line and second-line therapy in H. pylori infections in Iran. We aimed to consider the literature review of the various library and electronic databases (Science Direct, PubMed, and Google Scholar) until 2020. The frequency of bacterial resistance to tetracycline, ampicillin, trimethoprim, erythromycin, ofloxacin, and metronidazolewas found to be high in Iran, while the most effective antibiotics were clarithromycin, rifampin, rifampicin, tetracycline, amoxicillin, ciprofloxacin, levofloxacin, moxifloxacin, and azithromycin. The therapeutic choice for H. pylori eradication in Iran could be quadruple therapy using two antibiotics amoxicillin and metronidazole/clarithromycin for the first-line regimen, and a combination of furazolidone plus tetracycline/amoxicillin and bismuth plus proton pump inhibitor for the second-line regimen. Due to increased antibiotic resistance in our region, empirical therapy must be replaced by more targeted treatment based on antimicrobial drug resistance profiles obtained from patients. Although we limited our investigation on the H. pylori eradication regimens in Iran, the results can be generalized to any region as long as the patterns of resistance are the same.

An Updated Systematic Review and Meta-Analysis on the Helicobacter pylori Antibiotic Resistance in Iran (2010-2020)

This updated systematic review and meta-analysis followed two objectives: (1) to determine Helicobacter pylori antibiotic resistance in Iran during 2010-2020 and (2) to assess the trend of resistance from 1997 to 2020. A systematic search in multiple databases, including ISI Web of Knowledge, PubMed, Scopus, Google Scholar, and the Scientific Information Database (SID), was performed using MeSH-extracted keywords. Meta-analysis was done on extracted data from a total of 27 included citations published between 2010 and January 20, 2020. The overall mean prevalence of H. pylori resistance was 64.9% for metronidazole, 25.3% for clarithromycin, 20.7% for amoxicillin, 16.1% for tetracycline, 21.9% for levofloxacin, 22.8% for rifampicin, 27.2% for furazolidone, 32.3% for ciprofloxacin, and 38.7% for erythromycin. In addition, the prevalence of multidrug-resistant strains of H. pylori was 26.5% in Iran. The pooled prevalence of point mutations A2143G, A2142G, and A2142C associated with clarithromycin resistance were 46.6%, 37.2%, and 5.5%, respectively; mutations in frxA and rdxA genes associated with metronidazole resistance were 46.4% and 19.7%, respectively; gyrA and gyrB genes mutations among fluoroquinolone-resistant strains were 55.3% and 48.2%, respectively; and resistance associated with integrons was 47%. According to the present findings, resistance of H. pylori to antibiotics used for eradication therapy has reached an alarming level in Iran. Furthermore, the trend of H. pylori resistance has increased between 1997 and 2020. Hence, continuous surveillance on resistance patterns, logical prescription and appropriate consumption of antibiotics, and selecting effective therapeutic regimens in accordance with local resistance patterns are required to prevent further spread of resistance and ensuing treatment failures.

Helicobacter pylori antibiotic resistance and correlation with cagA motifs and homB gene

Objectives: Helicobacter pylori (H. pylori) infection caused by antibiotic-resistant strains represents a major public health threat that aggressively promotes gastric cancer progression. Antibiotic resistance evaluation is immensely important to counteract its emergence. Here we merely determine the prevalence of antibiotic resistance in H. pylori isolates and its correlation with cagA motifs and the homB gene. Methods: The antibiotic resistance pattern was investigated on 128 H. pylori isolated strains utilizing the disk diffusion method and study the correlation between it and the presence of pathogenic genes, cagA EPIYA motifs and homB gene, were accurately detected using the PCR. Results: The resistance rates to four antibiotics were 70.1% for metronidazole, 35.5% for amoxicillin, 7.2% for clarithromycin and 8.2% for tetracycline. Resistance phenotypes were separated into two groups, single resistance (63.2%) and multi-resistance (12.5%). The prevalence of cagA-ABCC resistant strains and homB⁺ resistant strains was significantly higher in cancer (p = 0.04 and p = 0.01, respectively) than those of other diseases. The prevalence of cagA-homB ⁺ resistance strains was 21.8% and had a significant correlation with PUD. A significant relationship was observed between amoxicillin resistant rate with ABC-homB (p = 0.0006). Conclusion: The Resistance rate to selected antibiotics in Shiraz is higher than years ago. The presence of cagA-homB ⁺ is associated with antibiotic resistance and also homB can be used as a marker to antibiotic resistance status prediction in H. pylori isolated in this area.

High Prevalence of Antibiotic Resistance in Iranian Helicobacter pylori Isolates: Importance of Functional and Mutational Analysis of Resistance Genes and Virulence Genotyping

The high prevalence of antibiotic resistance in Helicobacter pylori has become a great challenge in Iran. The genetic mutations that contribute to the resistance have yet to be precisely identified. This study aimed to investigate the prevalence of antibiotic resistance and virulence markers in Iranian H. pylori isolates and to analyze if there is any association between resistance and genotype. Antibiotic susceptibility patterns of 68 H. pylori isolates were investigated against metronidazole, clarithromycin, amoxicillin, rifampicin, ciprofloxacin, levofloxacin, and tetracycline by the agar dilution method. The frxA, rdxA, gyrA, gyrB, and 23S rRNA genes of the isolates were sequenced. The virulence genotypes were also determined using PCR. Metronidazole resistance was present in 82.4% of the isolates, followed by clarithromycin (33.8%), ciprofloxacin (33.8%), rifampicin (32.4%), amoxicillin (30.9%), levofloxacin (27.9%), and tetracycline (4.4%). Overall, 75% of the isolates were resistant to at least two antibiotics tested and considered as a multidrug resistance (MDR) phenotype. Most of the metronidazole-resistant isolates carried frameshift mutations in both frxA and rdxA genes, and premature termination occurred in positions Q5Stop and Q50Stop, respectively. Amino acid substitutions M191I, G208E, and V199A were predominantly found in gyrA gene of fluoroquinolone-resistant isolates. A2143G and C2195T mutations of 23S rRNA were found in four clarithromycin-resistant isolates. Interestingly, significant associations were found between resistance to metronidazole (MNZ) and cagA-, sabA-, and dupA-positive genotypes, with p = 0.0002, p = 0.0001, and p = 0.0001, respectively. Furthermore, a significant association was found between oipA “on” status and resistance to amoxicillin (AMX) (p = 0.02). The prevalence of H. pylori antibiotic resistance is high in our region, particularly that of metronidazole, clarithromycin, ciprofloxacin, and MDR. Simultaneous screening of virulence and resistance genotypes can help clinicians to choose the appropriate therapeutic regime against H. pylori infection.

Temporin-SHa and Its Analogs as Potential Candidates for the Treatment of Helicobacter pylori

Helicobacter pylori is one of the most prevalent pathogens colonizing 50% of the world's population and causing gastritis and gastric cancer. Even with triple and quadruple antibiotic therapies, H. pylori shows increased prevalence of resistance to conventional antibiotics and treatment failure. Due to their pore-forming activity, antimicrobial peptides (AMP) are considered as a good alternative to conventional antibiotics, particularly in the case of resistant bacteria. In this study, temporin-SHa (a frog AMP) and its analogs obtained by Gly to Ala substitutions were tested against H. pylori. Results showed differences in the antibacterial activity and toxicity of the peptides in relation to the number and position of D-Ala substitution. Temporin-SHa and its analog NST1 were identified as the best molecules, both peptides being active on clinical resistant strains, killing 90-100% of bacteria in less than 1 h and showing low to no toxicity against human gastric cells and tissue. Importantly, the presence of gastric mucins did not prevent the antibacterial effect of temporin-SHa and NST1, NST1 being in addition resistant to pepsin. Taken together, our results demonstrated that temporin-SHa and its analog NST1 could be considered as potential candidates to treat H. pylori, particularly in the case of resistant strains.

Multidrug resistance in Helicobacter pylori: current state and future directions

Introduction: Helicobacter pylori antibiotic resistance has increased worldwide and multidrug resistance (MDR), which seriously hampers eradication success of the frequent chronic infection, has often been reported. Areas covered: H. pylori MDR rates are discussed, mostly from recent articles published since 2015. Present approaches and future directions to counteract the MDR are outlined. Expert opinion: Alarming presence of triple, quadruple and, in some studies, quintuple and sextuple resistance was detected. Primary MDR rates ranged from <10% in most European countries to >40% in Peru. Post-treatment or overall MDR rates were >23-36% in about half of the studies. MDR prevalence has varied both among and within the countries. Factors linked to the MDR are national antibiotic consumption, antibiotic misuse, treatment failures and bacterial factors such as mutations, efflux pumps, and biofilms. Important directions to counteract the MDR increase can be optimization of present and new eradication regimens, wider use of bismuth-containing regimens, assessment of benefit of vonoprazan, new antibiotics such as newer fluoroquinolones and oxazolidinone analogues, adjuvants involving N-acetylcysteine and probiotics, anti-biofilm approaches using anti-biofilm peptides and rhamnolipid and development of vaccines and non-invasive tests for resistance detection. However, more efforts and studies are required. Strain susceptibility testing is increasingly important.

Prevalence of Antibiotic Resistance in Helicobacter pylori: A Systematic Review and Meta-analysis in World Health Organization Regions

BACKGROUND & AIMS

In 2017, the World Health Organization (WHO) designated clarithromycin-resistant Helicobacter pylori a high priority for antibiotic research and development. However, there are no clear data on the global distribution of resistance or its clinical effects. We performed a systematic review and meta-analysis to assess the distribution of H pylori resistance to commonly used antibiotics and to measure the association between antibiotic resistance and treatment failure.

METHODS

We searched publication databases for studies that assessed rates of H pylori resistance to clarithromycin, metronidazole, levofloxacin, amoxicillin, or tetracycline. Pooled estimates of primary and secondary resistance and 95% confidence intervals (CIs) were grouped by WHO region. The association between antibiotic resistance and treatment failure was measured by extracting data on treatment efficacy in patients with resistant and susceptible isolates and pooling odds ratios with 95% CIs.

RESULTS

We identified 178 studies, comprising 66,142 isolates from 65 countries. Primary and secondary resistance rates to clarithromycin, metronidazole, and levofloxacin were ≥15% in all WHO regions, except primary clarithromycin resistance in the Americas (10%; 95% CI, 4%-16%) and South-East Asia region (10%; 95% CI, 5%-16%) and primary levofloxacin resistance in the European region (11%; 95% CI, 9%-13%). There was considerable heterogeneity (I2 > 75%) among all analyses-this might have resulted from the grouping of resistance rates by country. Increasing antibiotic resistance was observed in most WHO regions. Resistance to clarithromycin was significantly associated with failure of clarithromycin-containing regimens (odds ratio, 6.97; 95% CI, 5.23-9.28; P < .001).

CONCLUSIONS

Resistance of H pylori to antibiotics has reached alarming levels worldwide, which has a great effect on efficacy of treatment. Local surveillance networks are required to select appropriate eradication regimens for each region.

Characterization of clarithromycin heteroresistance among Helicobacter pylori strains isolated from the antrum and corpus of the stomach

Mixed infections and heteroresistance of Helicobacter pylori contribute to decreased efficacy of treatments. This study aimed to investigate frequency of clarithromycin heteroresistance and its link with mixed infections, medication history, and disease severity. A total of 40 pairs of H. pylori strains were isolated from the antrum and corpus of 97 patients. Susceptibility of the strains to clarithromycin was measured by agar dilution method. Site-specific mutations of 23S rRNA at A2143G, A2142G, and A2142C positions were analyzed by PCR and genomic relatedness of pairs of the strains was determined by random amplified polymorphic DNA (RAPD)-PCR. The results showed a prevalence of 35% (14/40) clarithromycin resistance. Diversity of the antrum and corpus isolates in resistance to clarithromycin was detected among 17.5% (7/40) of the patients. Similarly, diversity in MIC value was also detected in two patients infected with the sensitive strains. Significant difference in frequency of resistance was detected among patients with peptic ulcer disease (PUD) (MIC90 32 μg/mL) and severe gastritis (MIC90 16 μg/mL), compared with those who suffered from non-ulcer dyspepsia (NUD) (MIC90 8 μg/mL) and chronic gastritis (MIC90 0.25 μg/mL). MIC values showed 8-32 folds increased levels in the corpus. A2142G, A2143G, and A2142C mutations were detected in three, two, and two patients, respectively, but not observed in 46% of the resistant strains. RAPD-PCR fingerprints showed identical molecular patterns for the isolates of the corpus and antrum in each patient. In conclusion, microevolution of H. pylori strains during chronic infection, rather than mixed infection, and inappropriate medication appear to be main reasons of treatment failure in adults.

Efficacy and Tolerability of Two Quadruple Regimens: Bismuth, Omeprazole, Metronidazole with Amoxicillin or Tetracycline as First-Line Treatment for Eradication of Helicobacter Pylori in Patients with Duodenal Ulcer: A Randomized Clinical Trial

AIM

To evaluate the efficacy and tolerability of tetracycline vs. high-dose amoxicillin in bismuth-based quadruple therapy for Helicobacter pylori(H. pylori) eradication.

METHODS

This randomized, open-label clinical trial included 228 patients with H.pylori infection and duodenal ulcer without a history of H.pylori treatment. Patients were randomly divided into two groups. The amoxicillin group received metronidazole 500mg, bismuth subcitrate 240mg, and amoxicillin 1000mg, all three times a day, plus omeprazole 20 mg twice a day, for 14 days. The tetracycline group received metronidazole 500mg three times a day; bismuth subcitrate240mg and tetracycline HCl 500mg, both four times a day; and omeprazole 20 mg twice a day, for 14 days. Evaluation for compliance and drug-relatedadverse effects were evaluated at the end of two weeks. Eight weeks after the end of treatment, the rate of H.pylori eradication was assessed by the C13urease breath test.

RESULTS

There were no significant demographic differences between the two groups. Eradication rate was higher with the amoxicillin-containing regimen than the tetracycline-containing regimen: 105/110 (95.51%; 95% confidence interval, 91.5%-99.3%) vs. 88/105 (83.8%; 95%CI, 76.7%-90.8%) by per-protocol analysis (p = 0.005) and 92.9% (95%CI, 88.1%-97.6%) vs. 76.5% (95%CI, 68.7%-84.2%) by intention-to-treat analysis (ITT, p = 0.001). Adverse effects were significant higher in the tetracycline groupthan in the amoxicillin group (65.2% vs. 43.4%; p = 0.001).

CONCLUSION

Bismuth-based quadruple therapy including high-dose amoxicillin and metronidazole achieved an acceptable rate of H.pylori infection eradication with good tolerance in patients with duodenal ulcer. This regimen can overcome treatment resistance in areas with high prevalence of metronidazole and clarithromycin resistance.

TRIAL REGISTRATION

The Thai Clinical Trial Registry (TCTR) 20170623004.

Antibiotic resistance of Helicobacter pylori to 16 antibiotics in clinical patients

BACKGROUND

Resistance of Helicobacter pylori (H. pylori) to antibiotics is increasing worldwide. To determine the status of H. pylori resistance and its patterns in clinical patients, an investigation utilizing susceptibility testing for commonly used antibiotics was needed.

METHODS

Total of 2283 H. pylori strains were collected from 2013 to 2016. The resistance and its patterns of these strains were tested by agar dilution method. The resistance rate and minimal inhibition concentration (MIC) in different gender groups were also analyzed.

RESULTS

The overall resistance rates were as following: amoxicillin (1.58%), clarithromycin (22.73%), levofloxacin (24.75%), furazolidone (1.49%), doxycycline (9.20%), cefetamet (97.20%), ceftriaxone (49.60%), cefuroxime (25.20%), gentamicin (3.73%), azithromycin (85.60%), rifampicin (2.80%), metronidazole (92.53%), ornidazole (94.27%), tinidazole (87.20%), ciprofloxacin (43.20%), and moxifloxacin (38.53%). There were only 64.08% strains pan-susceptible to amoxicillin, clarithromycin, levofloxacin, and furazolidone, followed by mono resistance (23.17%), double resistance (11.13%), triple resistance (1.36%), and quadruple resistance (0.26%). Significant differences in the resistance rate and MIC were also observed in different gender groups.

CONCLUSION

Antibiotic resistance trends of H. pylori is increasing in clinical patients. With the increasing resistance, it is imperative to individualized therapy based on the results of drug susceptibility testing.

Eradication of Helicobacter Pylori in Iran: A Review

Helicobacter pylori (H. pylori) infection is one of the most common bacterial infections, affecting almost half of the world’s population. It is associated with peptic ulcer disease, gastric adenocarcinoma, and lymphoma. In Iran, the prevalence of H. pylori infection has been reported to be between 36% and 90% in different geographic regions.

Several studies have assessed the efficacy of different therapeutic options for firstline and second-line H. pylori eradication in Iran; however, the results are conflicting. Therefore, we conducted a review to evaluate different studies in order to select the best options and to provide recommendations for H. pylori eradication in Iran. Accordingly, we searched through PubMed to obtain relevant randomized clinical trials published in English language up to June 2017.

According to our study, among first-line eradication regimens, bismuth-based furazolidone- or clarithromycin-containing quadruple therapies, hybrid regimen, and concomitant therapy seem to be appropriate options. Also, 10- or 14-day clarithromycin-containing triple therapy can be used if local H. pylori resistance to clarithromycin is known to be less than 15%.

For second-line H. pylori eradication, bismuth-based quadruple therapies and 14-day levofloxacin-based triple therapy can be used, provided that antibiotics other than those used in the first-line regimen are used. Third-line H. pylori eradication regimens have not been addressed in Iranian studies. However, most guidelines recommend treatment according to the results of culture and susceptibility testing.

Although we limited our investigation to H. pylori eradication regimens in Iran, the results are transferrable to any region as long as the patterns of antibiotic resistance are the same.

Occurrence of Mutations in the Antimicrobial Target Genes Related to Levofloxacin, Clarithromycin, and Amoxicillin Resistance in Helicobacter pylori Isolates from Buenos Aires City

Domain V of 23S rRNA, gyrA and gyrB Quinolones Resistance-Determining Region (QRDR), and pbp-1A gene point mutations were investigated in Helicobacter pylori-resistant isolates from three centres of Buenos Aires. Minimal inhibitory concentrations (MICs) were performed in 197 isolates from 52 H. pylori-positive naive patients by agar dilution method. Point mutations were achieved by amplification and sequencing of the target genes, and their association with resistance was determined by natural transformation assays. Resistance rates were as follows: metronidazole 28.8%, clarithromycin (CLA) 26.9%, levofloxacin (LEV) 32.7%, and amoxicillin (AMX) 7.6%. Nearly one-third of patients carried multidrug-resistant isolates. A2143G or A2142G in domain V of 23S-rRNA was found in all isolates showing high level of resistance to CLA (MIC >2 mg/L), accounting for 76.0% (38/50) of those with the resistant phenotype. The mutations A2267G or T1861C carried by 8/12 isolates with MIC 1-2 mg/L (low level) did not confer resistance by transformation. Substitutions at GyrA position 87 or 91, mainly N87K and D91G, were found in 92.8% (52/56) of the LEV-resistant isolates: 48 isolates with MIC 4-64 mg/L and 4/8 isolates with MIC 2 mg/L. The remaining four harboured K133N, also present in susceptible isolates. None of the substitutions in GyrB demonstrated to confer resistance. Transformation proved that PBP-1A N562Y and/or T556S substitutions confer the AMX resistance in our isolates, showing an additive effect. In conclusion, the usually reported mutations related to CLA, LEV, and AMX resistance were found in our isolates. However, low-level CLA resistance seems not to be due to mutations in Domain V of 23S rRNA gene.

Helicobacter pylori isolated from Iranian drinking water: vacA, cagA, iceA, oipA and babA2 genotype status and antimicrobial resistance properties

Despite the clinical importance of Helicobacter pylori in human gastric disorders, its exact route of transmission is still uncertain. Based on the contentious hypothesis and findings of previous investigations, water may play an important role in the transmission of H. pylori to humans. This study was carried out to investigate the vacA, cagA, oipA, iceA and babA2 genotype status and antimicrobial resistance properties of H. pylori strains isolated from the drinking water samples of four major provinces in Iran. A total of 400 drinking water samples were cultured and tested. H. pylori-positive strains were analyzed for the presence of various genotypes and antimicrobial resistance. Twelve of 400 (3%) water samples were positive for H. pylori. Samples from Isfahan province had the highest, while those from Shiraz had the lowest prevalence of H. pylori. The seasonal distribution was also determined, with the highest prevalence of bacteria in the summer season (7.36%). H. pylori strains harbored the highest levels of resistance against ampicillin (100%), erythromycin (75%), clarithromycin (75%), and trimethoprim (58.3%). The most commonly detected genotypes were vacAs1a (83.3%), vacAm1a (66.6%), vacAs2 (50%) and cagA (50%). The presence of similar genotypes in the H. pylori strains of drinking water and those of human clinical samples suggest that contaminated water maybe the sources of bacteria. Spiramycin and furazolidone are suggested for the treatment of cases of H. pylori infection.

Evaluation of Clarithromycin Resistance Among Iranian Helicobacter pylori Isolates by E-Test and Real-Time Polymerase Chain Reaction Methods

Background

Helicobacter pylori is an important pathogen of human gastric mucosa. Antibiotic resistance, especially resistance to clarithromycin is a major factor for treatment failure of H. pylori infections. The main mechanism of clarithromycin resistance in these bacteria is related to point mutations in three different locations of 23S rRNA gene.

Objectives

The aims of this study were to evaluate the resistance rate to clarithromycin among local H. pylori isolates by the E-test method and to determine the profile of point mutation in 23S rRNA by real-time polymerase chain reaction (PCR) method.

Patients and Methods

Eighty biopsy samples were collected from dyspeptic patients by endoscopy during 2011 - 2012. All samples were homogenized immediately and cultured on supplemented brucella blood agar and incubated under microaerophilic conditions. Further biochemical tests and ureC gene PCR was done for H. pylori confirmation. The H. pylori OC1096 strain was used as the control strain, simultaneously. Frequency of clarithromycin resistance was determined by the E-test method based on the clinical and laboratory standard institute (CLSI) standards. Point mutation profile was determined by real-time PCR and further analysis of melting curve, amplicon sequencing was done continuously.

Results

From 80 biopsy samples, 20 positive H. pylori isolates were detected and confirmed by biochemical tests and PCR method. Overall, 21.7% of the H. pylori isolates, showed clarithromycin resistance phenotype by use of the E-test. Also, the minimal inhibitory concentration of clarithromycin was determined as ≥ 0.5 mg/L by the E-test method. Only point mutation in the location of A2143G with melting temperature of 54.7°C was observed in all resistant isolates.

Conclusions

This study showed that the frequency of H. pylori clarithromycin resistance in Iran is relatively high. Since clarithromycin is not commonly used in Iran for H. pylori eradication, the high rate of resistance could be related to cross-reactivity between other macrolides. Therefore, macrolide antibiotics must be prescribed with precaution in any case of treatment other than H. pylori infections. All resistant isolates showed A2143G mutation in 23S rRNA as the dominant pattern of point mutation at least in Tehran H. pylori isolates.

Low efficacy of levofloxacin-doxycycline-based third-line triple therapy for Helicobacter pylori eradication in Italy

AIM: To evaluate a levofloxacin-doxycycline-based triple therapy with or without a susceptibility culture test in non-responders to Helicobacter pylori (H. pylori) eradication.

METHODS: A total of 142 (99 women, 43 men; mean 53.0 ± 12.7 years) non-responders to more than two H. pylori eradication therapies underwent susceptibility culture tests or were treated with a seven-day triple therapy consisting of esomeprazole, 20 mg b.i.d., levofloxacin, 500 mg b.i.d., and doxycycline, 100 mg b.i.d., randomly associated with (n = 71) or without (n = 71) Lactobacillus casei DG. H. pylori status was checked in all patients at enrollment and at least 8 wk after the end of therapy. Compliance and tolerability of regimens were also assessed.

RESULTS: H. pylori eradication was achieved in < 50% of patients [per prototol (PP) = 49%; intention to treat (ITT) = 46%]. Eradication rate was higher in patients administered probiotics than in those without (PP = 55% vs 43%; ITT = 54% vs 40%). Estimated primary resistance to levofloxacin was 18% and multiple resistance was 31%. Therapy was well tolerated, and side effects were generally mild, with only one patient experiencing severe effects.

CONCLUSION: Third-line levofloxacin-doxycycline triple therapy had a low H. pylori eradication efficacy, though the success and tolerability of this treatment may be enhanced with probiotics.