Antibiotic resistance and cagA gene correlation: A looming crisis of Helicobacter pylori

Investigation of metronidazole resistance-associated mutations and virulence genotypes in helicobacter pylori isolates from the Egyptian population: A cross-sectional study

INTRODUCTION

This cross-sectional study assesses the prevalence of metronidazole resistance-associated mutations and virulence genotypes in Helicobacter pylori (H. pylori) strains isolated from the Egyptian population. H. pylori infection is a significant public health concern, with antibiotic resistance challenging its eradication.

METHODS

Gastric biopsy samples were collected from symptomatic patients referred for upper gastrointestinal endoscopy at selected healthcare facilities. The study included 250 participants with symptoms suggestive of H. pylori infection and aged 18 years or older. Biopsy samples were obtained using standard endoscopic techniques, and H. pylori strains were isolated and identified in the laboratory. Antimicrobial susceptibility testing was conducted using standard methods. Molecular analysis, including polymerase chain reaction (PCR) and sequencing, was performed to identify metronidazole resistance-associated mutations (rdxA and frxA) and virulence genotypes (cagA and vacA).

RESULTS

Antimicrobial susceptibility testing revealed that 43.6 % of the isolates were resistant to metronidazole, while 11.8 %, 4.5 %, and 55.4 % were resistant to clarithromycin, amoxicillin, and levofloxacin. Molecular analysis identified rdxA and frxA mutations in 36.3 % and 31.8 % of the isolates, respectively, indicating metronidazole resistance-associated mutations. Additionally, 60.0 % of the isolates were positive for the cagA gene, and 80.0 % had the vacA s1 type, both associated with increased virulence. A significant association was found between metronidazole resistance and the presence of cagA gene, vacA s1 type, rdxA mutation, and frxA mutation. Statistical analysis revealed associations between specific mutations and virulence genotypes with respective odds ratios, indicating higher likelihoods of metronidazole resistance in isolates exhibiting these genetic characteristics.

CONCLUSIONS

This study highlights the prevalence of metronidazole resistance and the association between specific mutations and virulence genotypes in H. pylori strains isolated from the Egyptian population. The findings underscore the importance of monitoring antibiotic resistance patterns and understanding the genetic determinants of virulence in H. pylori for effective management and treatment strategies.

Drug Resistance Patterns of Commonly Used Antibiotics for the Treatment of Helicobacter pylori Infection among South Asian Countries: A Systematic Review and Meta-Analysis

Background: In South Asia, resistance to commonly used antibiotics for the treatment of Helicobacter pylori infection is increasing. Despite this, accurate estimates of overall antibiotic resistance are missing. Thus, this review aims to analyze the resistance rates of commonly used antibiotics for the treatment of H. pylori in South Asia. Methods: The systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. We searched five medical databases for relevant studies from inception to September 2022. A random effect model with a 95% confidence interval (CI) was used to calculate the pooled prevalence of antibiotic resistance. Results: This systematic review and meta-analysis included 23 articles, 6357 patients, 3294 Helicobacter pylori isolates, and 2192 samples for antibiotic resistance. The prevalences of antibiotic resistance to common antibiotics were clarithromycin: 27% (95%CI: 0.17–0.38), metronidazole: 69% (95%CI: 0.62–0.76), tetracycline: 16% (95%CI: 0.06–0.25), amoxicillin: 23% (95%CI: 0.15–0.30), ciprofloxacin: 12% (95%CI: 0.04–0.23), levofloxacin: 34% (95%CI: 0.22–0.47), and furazolidone: 14% (95%CI: 0.06–0.22). Subgroup analysis showed antibiotic resistances were more prevalent in Pakistan, India, and Bangladesh. Furthermore, a ten-year trend analysis showed the increasing resistance prevalence for clarithromycin (21% to 30%), ciprofloxacin (3% to 16%), and tetracycline (5% to 20%) from 2003 to 2022. Conclusion: This meta-analysis showed a high prevalence of resistance among the commonly used antibiotics for H. pylori in South Asian countries. Furthermore, antibiotic resistance has been increasing over the time of 20 years. In order to tackle this situation, a robust surveillance system, and strict adherence to antibiotic stewardship are required.

Clarithromycin-resistant H. pylori primary strains and virulence genotypes in the Northeastern region of Brazil

The increase of H. pylori resistance to clarithromycin is a concern. This study evaluated the prevalence of H. pylori’s primary resistance to clarithromycin and its association with virulence factors in adult dyspeptic patients and asymptomatic children. The gastric mucosa from patients (153 gastritis, 24 gastric cancer, 21 peptic ulcer) and gastric juice obtained by string test from 24 H. pylori and 23S rRNA positive asymptomatic children were included. The clarithromycin resistance was assessed by TaqMan RT-PCR 23S rRNA point mutations, A2142G and/or A2143G, and H. pylori virulence markers by PCR. Overall, the clarithromycin resistance was 14.4% (32/222), 14.2% in adults, and 12% in children, whereas origin, gender, and disease were not distinctive factors. The most prevalent point mutation was A2143G (62.5%). The point mutation was significantly less frequent in cagA-positive (11.4%) than in cagA-negative (23.6%) strains (p=0.03 OR = 0.4 95%CI = 0.19 - 0.91) as well as in cagE-positive (10.2%), cagE-negative (21.2%) (p=0.03 OR: 0.4 I.C:0.20-0.91). No difference was found in iceA or vacA alleles genotypes. Primary resistance to clarithromycin was lower than that reported in Southeast Brazil. The cagA and cagE positive H. pylori samples have few point mutations suggesting that individuals infected with virulent strains may be more susceptible to anti-H. pylori treatment.

Clinical relevance of the cagA and vacA s1m1 status and antibiotic resistance in Helicobacter pylori: a systematic review and meta-analysis

BACKGROUND

The role of Helicobacter pylori (H. pylori) virulence factors of such as vacA s1m1 and cagA in designating clinical outcomes and eradication rate has been deeply challenged in the last decade. The goal of this analysis was to identify the potential relevance between cagA and vacA genotypes with reported antibiotic resistance observed in clinical H. pylori isolates.

METHODS

This literature search was conducted in databases such as Clarivate analytics, PubMed, Scopus, EMBASE, DOAJ, and Google Scholar by April 2022, regardless of language restrictions and publication date. Quality of the included studies was assessed by the Newcastle-Ottawa scale. Statistical analysis of retrieved studies was fulfilled using Comprehensive Meta-Analysis software version 2.2. Following quality appraisal of eligible studies, potential association between the status of cagA and vacA genes with resistance to clarithromycin, metronidazole, amoxicillin, tetracycline, and levofloxacin was measured using odds ratio with 95% confidence interval. We also used sensitivity analyses and meta-regression to eliminate the source of heterogeneity from the overall estimates. Publication bias was assessed using funnel plot, Egger's test, Begg's test with the trim and fill procedure to assess the presence and magnitude of publication bias in the included studies.

RESULTS

Our findings suggested that a significant relationship between cagA status ‎and increase resistance ‎to metronidazole (OR: 2.69; 95% CI: 1.24-5.83‎‏‎). In subgroup analysis, we ‎found that in the Western ‎population, infection with cagA-positive strains could be led to increase in ‎the resistance to ‎metronidazole (OR: 1.59; 95% CI: ‎0.78-3.21‎‏‎), ‎amoxicillin (OR: ‎19.68‎; 95% CI: 2.74-‎‎141.18), ‎and ‎levofloxacin (OR: ‎11.33; 95% CI: ‎1.39-‎‎91.85). After implementation of trim and fill method, the adjusted OR was not significantly differed from original estimates which in turn represented our subgroup analysis was statistically robust. On the other hand, vacA ‎genotypes usually ‎reduce the antibiotic resistance of this bacterium, so that vacA s1m1 significantly reduces the ‎resistance to ‎metronidazole (OR: 0.41; 95% CI: 0.20-0.86‎‏‎). Surprisingly, resistance of vacA s2m2 strains to antibiotics was low, the reason may be due ‎to the non-inflammatory properties of strains containing vacA s2m2. The meta-regression and sensitivity analyses successfully reduced the effect of heterogeneity from the overall estimates. In addition, although the pooled OR is reduced after trim and fill adjustment but results do not change the conclusion regarding vacA genotypes and antibiotic resistance.

CONCLUSIONS

According to our findings, it was clearly demonstrated that cagA-positive strains are resistance to metronidazole, especially in Western countries. In Western countries, vacA s1m1 increases resistance to amoxicillin and levofloxacin. Based on the present findings, the vacA s1m1 genotype significantly increases resistance to metronidazole, while the vacA s1m2 decreases resistance to clarithromycin and metronidazole. Resistance to antibiotics in less virulent (vacA s2m2) strains is statistically significant lower than others.

Correlation between clarithromycin resistance, virulence factors and clinical characteristics of the disease in Helicobacter pylori infected patients in Shahrekord, Southwest Iran

The purpose of this study was to determine the mutations associated with clarithromycin resistance in Helicobacter pylori strains isolated from biopsy samples that were collected from the endoscopic ward of Shahrekord Hajar teaching Hospital and also to study the frequency of virulence factor and their correlation and pathological findings with clarithromycin resistance during the years 2019-2020. In this cross-sectional descriptive study, 152 patients with Helicobacter pylori infection were considered, and then, two common A2142G and A2143G mutations in the 23SrRNA gene associated with resistance were analyzed by Real-time PCR (Taq man). The presence of vacA, iceA1, iceA2, cagA, babA2, and oipA virulence genes was investigated by PCR and electrophoresis in 8% polyacrylamide gel. Then, data were analyzed using the relevant statistical tests. In this study, the frequency of Helicobacter pylori was 76% and the frequency of mutant isolates was 57.2%. The frequencies of A2142G and A2143G point mutations were 42.1% and 28.3%. There was a significant correlation among oipA, vacA, and iceA1 virulence factors, type of disease, chronic inflammatory score, and glandular atrophy with the antibiotic resistance to clarithromycin. There was no significant correlation between the age and sex of the patients with antibiotic resistance. According to the results of this study, it seems that the use of clarithromycin to combat this bacterium should be limited.

Antibiotic resistance in Pakistan: a systematic review of past decade

Background

During the last six decades, extensive use of antibiotics has selected resistant strains, increasing the rate of fatal infectious diseases, and exerting an economic burden on society. This situation is widely accepted as a global problem, yet its degree is not well elucidated in many regions of the world. Up till now, no systemic analysis of Antimicrobial resistance (AMR) in Pakistan has been published. The current study aims to describe the antibiotic-resistance scenario of Pakistan from human samples of the last 10 y, to find the gaps in surveillances and methodology and recommendations for researchers and prescribers founded on these outcomes.

Methods

Original research articles analyzed the pattern of Antibiotic resistance of any World Health Organization (WHO) enlisted priority pathogens in Pakistan (published onward 2009 till March 2020), were collected from PubMed, Google scholar, and PakMedi Net search engines. These articles were selected based on predefined inclusion and exclusion criteria. Data about the study characteristics and antibiotic-resistance for a given bacterium were excluded from literature. Antibiotic resistance to a particular bacterium was calculated as a median resistance with 95% Confidence Interval (CI).

Results

Studies published in the last 10 y showed that Urinary Tract Infection (UTI) is the most reported clinical diagnosis (16.1%) in Pakistan. E. coli were reported in 28 (30.11%) studies showing high resistance to antibiotics’ first line. Methicillin-resistant Staphylococcus aureus (MRSA) was found in 49% of S. aureus’ total reported cases. Phenotypic resistance pattern has mostly been evaluated by Disk Diffusion Method (DDM) (82.8%), taken Clinical Laboratory Standards Institute (CLSI) as a breakpoint reference guideline (in 79.6% studies). Only 28 (30.11%) studies have made molecular identification of the resistance gene. blaTEM (78.94% in Shigella spp) and blaNDM-1 (32.75% in Klebsiella spp) are the prominent reported resistant genes followed by VanA (45.53% in Enterococcus spp), mcr-1 (1.61% in Acinetobacter spp), and blaKPC-2 (31.67% in E. coli). Most of the studies were from Sindh (40.86%), followed by Punjab (35.48%), while Baluchistan’s AMR data was not available.

Conclusion

Outcomes of our study emphasize that most of the pathogens show high resistance to commonly used antibiotics; also, we find gaps in surveillances and breaches in methodological data. Based on these findings, we recommend the regularization of surveillance practice and precise actions to combat the region’s AMR.

Helicobacter pylori Virulence Factor Genotyping

Helicobacter pylori (H. pylori) infection causes chronic gastritis, peptic ulcers, gastric adenocarcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma. Bacterial, host, and environmental factors influence the progression of disease from superficial gastritis to cancer. H. pylori is genetically diverse, and expression of its specific virulence factors has been linked to increased risk of more severe pathologies. Described in this chapter is a protocol for detecting important H. pylori virulence factors by firstly extracting DNA from culture material or stomach tissue biopsies, followed by PCR amplification and agarose gel electrophoresis.

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.

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 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.

Can bacterial virulence factors predict antibiotic resistant Helicobacter pylori infection?

AIM

To evaluate the association between virulence factor status and antibiotic resistance in Helicobacter pylori (H. pylori)-infected patients in Ireland.

METHODS

DNA was extracted from antral and corpus biopsies obtained from 165 H. pylori-infected patients. Genotyping for clarithromycin and fluoroquinolone-mediating mutations was performed using the Genotype HelicoDR assay. cagA and vacA genotypes were investigated using PCR.

RESULTS

Primary, secondary and overall resistance rates for clarithromycin were 50.5% (n = 53/105), 78.3% (n = 47/60) and 60.6% (n = 100/165), respectively. Primary, secondary and overall resistance rates for fluoroquinolones were 15.2% (n = 16/105) and 28.3% (n = 17/60) and 20% (n = 33/165), respectively. Resistance to both antibiotics was 12.4% (n = 13/105) in treatment-naïve patients, 25% (n = 15/60) in those previously treated and 17% (n = 28/165) overall. A cagA-positive genotype was detected in 22.4% (n = 37/165) of patient samples. The dominant vacA genotype was S1/M2 at 44.8% (n = 74/165), followed by S2/M2 at 26.7% (n = 44/165), S1/M1 at 23.6% (n = 39/165) and S2/M1 at 4.8% (n = 8/165). Primary clarithromycin resistance was significantly lower in cagA-positive strains than in cagA-negative strains [32% (n = 8/25) vs 56.3% (n = 45/80) P = 0.03]. Similarly, in patients infected with more virulent H. pylori strains bearing the vacA s1 genotype, primary clarithromycin resistance was significantly lower than in those infected with less virulent strains bearing the vacA s2 genotype, [41% (n = 32/78) vs 77.8% (n = 21/27) P = 0.0001]. No statistically significant association was found between primary fluoroquinolone resistance and virulence factor status.

CONCLUSION

Genotypic H. pylori clarithromycin resistance is high and cagA-negative strains are dominant in our population. Less virulent (cagA-negative and vacA S2-containing) strains of H. pylori are associated with primary clarithromycin resistance.

Primary antibiotic resistance and its relationship with cagA and vacA genes in Helicobacter pylori isolates from Algerian patients

The epidemiology of Helicobacter pylori resistance to antibiotics is poorly documented in Africa and especially in Algeria. The aim of our study was to determine the antibiotic resistance rates, as well as its possible relationship with VacA and CagA virulence markers of isolates from Algerian patients. One hundred and fifty one H. pylori isolate were obtained between 2012 and 2015 from 200 patients with upper abdominal pain. Antimicrobial susceptibility testing was performed for amoxicillin, clarithromycin, metronidazole, ciprofloxacin, rifampicin and tetracycline. Molecular identification of H. pylori and the detection of vacA and cagA genes were performed using specific primers. We found that H. pylori was present in 83.5% of collected biopsies, 54.9% of the samples were cagA positive, 49.67% were vacA s1m1, 18.30% were vacA s1m2 and 25.49% were vacA s2m2. Isolates were characterized by no resistance to amoxicillin (0%), tetracycline (0%), rifampicin (0%), a high rate of resistance to metronidazole (61.1%) and a lower rate of resistance to clarithromycin (22.8%) and ciprofloxacin (16.8%). No statically significant relationship was found between vagA and cagA genotypes and antibiotic resistance results (p > 0.5) except for the metronidazole, which had relation with the presence of cagA genotype (p = 0.001).

The effect of virulence genotypes of Helicobacter pylori on eradication therapy in children

BACKGROUND/AIM

It is important to eradicate Helicobacter pylori at an early stage in patients during childhood to potentially prevent the development of H. pylori-related diseases. Studies have demonstrated that the virulence genotype of H. pylori influences the efficacy of eradication therapy. The efficacy of triple therapy has decreased significantly, which has seriously affected the clinical outcome of children with H. pylori infection. In this study we aimed to investigate the influence of virulence genotypes of H. pylori on triple eradication therapy in children.

PATIENTS AND METHODS

H. pylori strains were isolated from the gastric antrum mucosa in children with upper gastrointestinal symptoms. Polymerase chain reaction (PCR) was conducted to determine the H. pylori cagA, vacA, and iceA genotypes. All patients with H. pylori infection were administered 14-day triple therapy. After drug withdrawal for at least 4 weeks, the ¹³C-urea breath test (¹³C-UBT) was used to observe the therapeutic effect of H. pylori eradication. The eradication rates were evaluated by intention-to-treat (ITT) and per-protocol (PP) analyses.

RESULTS

A total of 107 patients were enrolled in this study. Nine patients were lost to follow-up, and 98 patients were administered eradication therapy. Based on ITT and PP analyses, the H. pylori eradication rate was 64.5% (69/107) and 70.4% (69/98), respectively. Among the successful eradication groups, the cagA-positive, vacA s1a, vacA s1c, vacA m1, vacA m2, iceA 1, and iceA 2 genes were identified in 72.8%, 68.1%, 76.9%, 60.0%, 74.6%, 71.8%, and 75.0% of strains, respectively. Of the unsuccessful eradication groups, the cagA-positive, vacA s1a, vacA s1c, vacA m1, vacA m2, iceA 1, and iceA 2 genes were identified in 27.2%, 31.9%, 23.1%, 40.0%, 25.4%, 28.2%, and 25.0% of strains, respectively. No statistically significant differences were noted in the detection rate of the H. pylori genotypes between the H. pylori successful and unsuccessful eradication groups (P > 0.05).

CONCLUSIONS

The cagA, vacA, and iceA genotypes of H. pylori are not associated with the efficacy of omeprazole-based triple therapy on the eradication of H. pylori infection in children.

Surveillance of Helicobacter pylori Antibiotic Susceptibility in Indonesia: Different Resistance Types among Regions and with Novel Genetic Mutations

Information regarding Helicobacter pylori antibiotic resistance in Indonesia was previously inadequate. We assessed antibiotic susceptibility for H. pylori in Indonesia, and determined the association between virulence genes or genetic mutations and antibiotic resistance. We recruited 849 dyspeptic patients who underwent endoscopy in 11 cities in Indonesia. E-test was used to determine the minimum inhibitory concentration of five antibiotics. PCR-based sequencing assessed mutations in 23S rRNA, rdxA, gyrA, gyrB, and virulence genes. Next generation sequencing was used to obtain full-length sequences of 23S rRNA, infB, and rpl22. We cultured 77 strains and identified 9.1% with clarithromycin resistance. Low prevalence was also found for amoxicillin and tetracycline resistance (5.2% and 2.6%, respectively). In contrast, high resistance rates to metronidazole (46.7%) and levofloxacin (31.2%) were demonstrated. Strains isolated from Sumatera Island had significantly higher metronidazole resistance than those from other locations. Metronidazole resistant strains had highly distributed rdxA amino acid substitutions and the 23S rRNA A2143G mutation was associated with clarithromycin resistance (42.9%). However, one strain with the highest MIC value had a novel mutation in rpl22 without an A2143G mutation. Mutation at Asn-87 and/or Asp-91 of gyrA was associated with levofloxacin-resistance and was related to gyrB mutations. In conclusions, although this is a pilot study for a larger survey, our current data show that Indonesian strains had the high prevalence of metronidazole and levofloxacin resistance with low prevalence of clarithromycin, amoxicillin, and tetracycline resistance. Nevertheless, clarithromycin- or metronidazole-based triple therapy should be administered with caution in some regions of Indonesia.

Emerging Helicobacter pylori levofloxacin resistance and novel genetic mutation in Nepal

Background

The prevalence of Helicobacter pylori antibiotic susceptibility in the Nepalese strains is untracked. We determined the antibiotic susceptibility for H. pylori and analyzed the presence of genetic mutations associated with antibiotic resistance in Nepalese strains.

Results

This study included 146 consecutive patients who underwent gastroduodenal endoscopy in Kathmandu, Nepal. Among 42 isolated H. pylori, there was no resistance to amoxicillin and tetracycline. In contrast, similar with typical South Asian patterns; metronidazole resistance rate in Nepalese strains were extremely high (88.1 %, 37/42). Clarithromycin resistance rate in Nepalese strains were modestly high (21.4 %, 9/42). Most of metronidazole resistant strains had highly distributed rdxA and frxA mutations, but were relative coincidence without a synergistic effect to increase the minimum inhibitory concentration (MIC). Among strains with the high MIC, 63.6 % (7/11) were associated with frameshift mutation at position 18 of frxA with or without rdxA involvement. However, based on next generation sequencing data we found that one strain with the highest MIC value had a novel mutation in the form of amino acid substituted at Ala-212, Gln-382, Ile-485 of dppA and Leu-145, Thr-168, Glu-117, Val-121, Arg-221 in dapF aside from missense mutations in full-length rdxA. Mutations at Asn-87 and/or Asp-91 of the gyrA were predominantly in levofloxacin-resistant strains. The gyrB mutation had steady relationship with the gyrA 87–91 mutations. Although three (44.4 %) and two (22.2 %) of clarithromycin resistant strains had point mutation on A2143G and A2146G, we confirmed the involvement of rpl22 and infB in high MIC strains without an 23SrRNA mutation.

Conclusions

The rates of resistance to clarithromycin, metronidazole and levofloxacin were high in Nepalese strains, indicating that these antibiotics-based triple therapies are not useful as first-line treatment in Nepal. Bismuth or non-bismuth-based quadruple regimens, furazolidone-based triple therapy or rifabutin-based triple therapy may become alternative strategy in Nepal.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0873-6) contains supplementary material, which is available to authorized users.

In vitro antimicrobial susceptibility of Helicobacter pylori to nine antibiotics currently used in Central Italy

OBJECTIVE

Helicobacter pylori expresses an increased resistance in respect to antimicrobials currently used in therapy. The aim of this study was to evaluate the antimicrobial profiles of H. pylori isolates to nine conventional antibiotics used in a Central Region (Abruzzo) of Italy.

MATERIALS AND METHODS

Biopsies were taken from antrum and fundus of 112 adult and 3 children with Urea Breath Test positive with dyspeptic symptoms and analyzed for H. pylori culture and antibacterial activity. Antimicrobial susceptibility tests were performed for clarithromycin, metronidazole, levofloxacin, moxifloxacin, ciprofloxacin, tetracycline, amoxicillin, ampicillin, and rifabutin by a modified agar dilution susceptibility test.

RESULTS

Bacterial culture was successful in 100 out of 115 patients. Helicobacter pylori strains were isolated from 98 antrum and 83 fundus samples. The rate of recovery of H. pylori strains was 90.50% (181/200). The percentages of resistance were as follows: clarithromycin 72.44% antrum, 72.28% fundus; metronidazole 34.69% antrum, 42.16% fundus; levofloxacin 42.85% antrum, 53.01% fundus; moxifloxacin 37.35% antrum, 46.57% fundus; ciprofloxacin 39.47% antrum, 44.28% fundus; tetracycline 2.63% antrum, 2.85% fundus; amoxicillin 1.02% antrum, 1.20% fundus; ampicillin 0% antrum and fundus and rifabutin 0% antrum, 1.20% fundus. A total of 35 subjects harbored multi-resistant strains.

CONCLUSIONS

This study underlines the high rate of resistance to clarithromycin, metronidazole and quinolones, which may reflect an overuse of them. Culture and susceptibility test, should be performed to prevent the emergence of multi-resistance and to assess an efficacious regimen.

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.

The Primary Resistance of Helicobacter pylori in Taiwan after the National Policy to Restrict Antibiotic Consumption and Its Relation to Virulence Factors-A Nationwide Study

Objective

The Taiwan Government issued a policy to restrict antimicrobial usage since 2001. We aimed to assess the changes in the antibiotic consumption and the primary resistance of H. pylori after this policy and the impact of virulence factors on resistance.

Methods

The defined daily dose (DDD) of antibiotics was analyzed using the Taiwan National Health Insurance (NHI) research database. H. pylori strains isolated from treatment naïve (N=1395) and failure from prior eradication therapies (N=360) from 9 hospitals between 2000 and 2012 were used for analysis. The minimum inhibitory concentration was determined by agar dilution test. Genotyping for CagA and VacA was determined by PCR method.

Results

The DDD per 1000 persons per day of macrolides reduced from 1.12 in 1997 to 0.19 in 2008, whereas that of fluoroquinolones increased from 0.12 in 1997 to 0.35 in 2008. The primary resistance of amoxicillin, clarithromycin, metronidazole, and tetracycline remained as low as 2.2%, 7.9%, 23.7%, and 1.9% respectively. However, the primary levofloxacin resistance rose from 4.9% in 2000–2007 to 8.3% in 2008–2010 and 13.4% in 2011–2012 (p=0.001). The primary resistance of metronidazole was higher in females than males (33.1% vs. 18.8%, p<0.001), which was probably attributed to the higher consumption of nitroimidazole. Neither CagA nor VacA was associated with antibiotic resistance.

Conclusions

The low primary clarithromycin and metronidazole resistance of H. pylori in Taiwan might be attributed to the reduced consumption of macrolides and nitroimidazole after the national policy to restrict antimicrobial usage. Yet, further strategies are needed to restrict the consumption of fluoroquinolones in the face of rising levofloxacin resistance.

Appropriate first-line regimens to combat Helicobacter pylori antibiotic resistance: an Asian perspective

Asia has the largest population of any continent and the highest incidence of gastric cancer in the world, making it very important in the context of Helicobacter pylori infection. According to current guidelines, standard triple therapy containing a proton pump inhibitor (PPI) and two antibiotics; amoxicillin (AMX) and clarithromycin (CAM) or metronidazole (MNZ), is still the preferred first-line regimen for treatment of H. pylori infection. However, the efficacy of legacy triple regimens has been seriously challenged, and they are gradually becoming ineffective. Moreover, some regions in Asia show patterns of emerging antimicrobial resistance. More effective regimens including the bismuth and non-bismuth quadruple, sequential, and dual-concomitant (hybrid) regimens are now replacing standard triple therapies as empirical first-line treatments on the basis of the understanding of the local prevalence of H. pylori antimicrobial resistance. Selection of PPI metabolized by the non-enzymatic pathway or minimal first pass metabolism and/or increasing dose of PPI are important to increase H. pylori eradication rates. Therefore, local antibiotic resistance surveillance updates, selection of appropriate first-line regimens with non-enzymatic PPI and/or increased doses of PPI, and detailed evaluation of patients' prior antibiotic usage are all essential information to combat H. pylori antibiotic resistance in Asia.

Correlation of ABH blood group antigens secretion with Helicobacter pylori infection in Pakistani patients

OBJECTIVES

A and B blood group antigens are fucosylated carbohydrate present on human erythrocytes and body secretions. Their presence in body secretions depends on the expression of a dominant allele of secretor gene FUT2 and is correlated with susceptibility to various infectious and non-infectious diseases. We investigated the correlation of blood group and ABH antigen secretion with Helicobacter pylori infection and gastroduodenal symptoms and analysed the distribution of babA gene among ABH secretors and non-secretors.

METHODS

Two hundred and ninety patients who underwent gastroduodenal endoscopy during 2011 to 2012 participated. Gastric biopsy, saliva and blood samples were obtained from every patient. Gastric biopsies were subjected to rapid urease test and PCR for the detection of H. pylori and babA gene. Blood grouping and ABH antigens secretions were determined by Lewis blood group phenotyping and haemagglutination inhibition test.

RESULTS

50.34% of patients were ABH antigen secretors and 45.51% non-secretors. Distribution analysis of blood group revealed that 40 blood group B, 67 blood group A 20 blood group O and 19 blood group AB patients secreted ABH antigens in saliva. Fifty-six blood group O, 19 blood group B, 32 blood group A and 17 blood group AB patients were non-secretors. Gastroduodenal complaints were common among non-secretors. Sixty-two percent of patients with a combination of duodenal ulcer and gastro-oesophageal reflux and 54% of patients with gastritis were non-secretors. Of 290 samples, 31.02% were positive for H. pylori. Thirty percent of these tested positive for babA gene; the majority belonged to non-secretor blood group O.

CONCLUSIONS

Our results suggest that the infection of H. pylori is correlated with ABO blood groups and blood group antigens secretion in body fluids.

Analysis of clinical isolates of Helicobacter pylori in Pakistan reveals high degrees of pathogenicity and high frequencies of antibiotic resistance

BACKGROUND

Antibiotic resistance in Helicobacter pylori contributes to failure in eradicating the infection and is most often due to point and missense mutations in a few key genes.

METHODS

The antibiotic susceptibility profiles of H. pylori isolates from 46 Pakistani patients were determined by Etest. Resistance and pathogenicity genes were amplified, and sequences were analyzed to determine the presence of mutations.

RESULTS

A high percentage of isolates (73.9%) were resistant to metronidazole (MTZ), with considerable resistance to clarithromycin (CLR; 47.8%) and amoxicillin (AML; 54.3%) also observed. Relatively few isolates were resistant to tetracycline (TET; 4.3%) or to ciprofloxacin (CIP; 13%). However, most isolates (n = 43) exhibited resistance to one or more antibiotics. MTZ-resistant isolates contained missense mutations in oxygen-independent NADPH nitroreductase (RdxA; 8 mutations found) and NADH flavin oxidoreductase (FrxA; 4 mutations found). In the 23S rRNA gene, responsible for CLR resistance, a new point mutation (A2181G) and 4 previously reported mutations were identified. Pathogenicity genes cagA, dupA, and vacA s1a/m1 were detected frequently in isolates which were also found to be resistant to MTZ, CLR, and AML. A high percentage of CagA and VacA seropositivity was also observed in these patients. Phylogenetic analysis of partial sequences showed uniform distribution of the 3' region of cagA throughout the tree.

CONCLUSIONS

We have identified H. pylori isolates in Pakistan which harbor pathogenicity genes and worrying antibiotic resistance profiles as a result of having acquired multiple point and missense mutations. H. pylori eradication regimens should therefore be reevaluated in this setting.

The problem of Helicobacter pylori resistance to antibiotics: a systematic review in Latin America

OBJECTIVES

Latin America has a high prevalence of Helicobacter pylori infection and associated diseases, including gastric cancer. Antibiotic therapy can eradicate the bacterial infection and decrease associated morbidity and mortality. To tailor recommendations for optimal treatments, we summarized published literature and calculated region- and country-specific prevalences of antibiotic resistance.

METHODS

Searches of PubMed and regional databases for observational studies evaluating H. pylori antibiotic resistance yielded a total of 59 independent studies (56 in adults, 2 in children, and 1 in both groups) published up to October 2013 regarding H. pylori isolates collected between 1988 and 2011. Study-specific prevalences of primary resistance to commonly prescribed antibiotics were summarized using random-effects models. Between-study heterogeneity was assessed by meta-regression. As a sensitivity analysis, we extended our research to studies of patients with prior H. pylori-eradication therapy.

RESULTS

Summary prevalences of antimicrobial primary resistance among adults varied by antibiotic, including 12% for clarithromycin (n=35 studies), 53% for metronidazole (n=34), 4% for amoxicillin (n=28), 6% for tetracycline (n=20), 3% for furazolidone (n=6), 15% for fluoroquinolones (n=5), and 8% for dual clarithromycin and metronidazole (n=10). Resistance prevalence varied significantly by country, but not by year of sample collection. Analyses including studies of patients with prior therapy yielded similar estimates. Pediatric reports were too few to be summarized by meta-analysis.

CONCLUSIONS

Resistance to first-line anti-H. pylori antibiotics is high in Latin American populations. In some countries, the empirical use of clarithromycin without susceptibility testing may not be appropriate. These findings stress the need for appropriate surveillance programs, improved antimicrobial regulations, and increased public awareness.

Changes in Antibiotic Susceptibility of Helicobacter pylori in the Course of Eight Years in the Zaanstreek Region in The Netherlands

Background. Failure of anti-Helicobacter therapy is the result noncompliance and resistance to the prescribed antibiotics. Aim. Antibiotic susceptibility of H. pylori was determined in native Dutch patients and patients of Turkish descent. Methods. In a period of eight years a total of 925 strains of H. pylori were cultured. Bacterial susceptibility was successfully determined in 746 (80.6%) of these isolates. Three hundred and nine strains (33%) originated from patients of Turkish descent. Results. In total clarithromycin resistance was found in 146 (20.5%) strains, metronidazole resistance in 147 (19.9%) strains. Amoxicillin resistance was found to be present in five strains. There is a slight but nonsignificant decrease in the percentage of clarithromycin-resistant strains in the consecutive period of eight years from 20% to 18%. No changes were seen in the consecutive years in metronidazole resistance. The number of clarithromycin-resistant strains decreased in Turkish patients, not in native Dutch patients. Conclusion. Resistance did not change significantly in consecutive years. But clinicians should take not only the antibiotic history into account but also ethnicity before prescribing metronidazole or clarithromycin.