Molecular Detection of Antibiotic Resistance in South African Isolates of Helicobacter pylori. Gastroenterol Res Pract. 2013;2013:259457. [PMID: 23710166 PMCID: PMC3655586 DOI: 10.1155/2013/259457]

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

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

Molecular detection of Helicobacter pylori and clarithromycin resistance in gastric biopsies: a prospective evaluation of RIDA®GENE Helicobacter pylori assay

Background: Empirical treatment of Helicobacter pylori (HP) depends on the local prevalence of clarithromycin resistance but data are lacking and culturing of HP is time-consuming. We evaluated RIDA®GENE Helicobacter pylori assay (r-biopharm), a quantitative PCR assay for detecting HP and clarithromycin resistance mutations in gastric biopsies.Material/methods: Gastric biopsies were obtained from each of 436 consecutive patients referred for gastroscopic investigation and results of qPCR were compared to culture and immunohistochemical staining (IHCS).Results: Of 436 samples, 47 were positive for HP by PCR (11%), 42 by culture (9.7%) and 44 by IHCS (10%). Compared to culture, sensitivity and specificity of the qPCR were 100% and 99%, respectively, and 96% and 99% compared to IHCS. The sensitivity and specificity for clarithromycin resistance detection were 92% and 97%, respectively.Conclusions: RIDA®GENE Helicobacter pylori assay reliably and rapidly detects HP and its resistance to clarithromycin in human gastric biopsies.

Helicobacter pylori 23S rRNA gene A2142G, A2143G, T2182C, and C2195T mutations associated with clarithromycin resistance detected in Sudanese patients

Background

Clarithromycin resistant Helicobacter pylori (H. pylori) strains represent a worldwide health problem. These stains are usually carrying mutations within the 23S rRNA gene associated with clarithromycin resistance. This study aimed to detect H. pylori and clarithromycin resistant associated mutations from Sudanese patients with gastritis symptoms.

Materials and methods

Two hundred and eighty-eight gastric biopsies were collected using gastrointestinal endoscopy from patients with gastritis symptoms in different hospitals in Khartoum state. H. pylori was detected by PCR using primer targeting 16S rRNA. Then allele-specific PCR and DNA sequencing were used to screen for the presence of A2142G and A2143G point mutations.

Results

Out of 288 samples, H. pylori was detected in 88 (~ 30.6%) samples by 16 s RNA. Allele-specific PCR detected the variant A2142G in 9/53 (~ 17%) sample, while A2143G mutation was not found in any sample. The DNA sequencing revealed the presence of mutations associated with clarithromycin-resistance in 36% (9/25) of samples; the A2142G was present in one sample, A2143G in 5 samples and T2182C in 4 samples. Additionally, another point mutation (C2195T) was detected in 3 samples. There was no association of 23S rRNA gene point mutations with gender, age group, and patients’ geographical distribution.

Conclusion

This study revealed a high frequency (36%) of mutations associated with clarithromycin resistance using DNA sequencing of the 23S rRNA gene’s V domain. This information should be taken into consideration to avoid eradication therapy failing.

Infections with Helicobacter pylori and challenges encountered in Africa

Helicobacter pylori (H. pylori) is the causative agent of gastritis, peptic ulcer disease, mucosa associated lymphoid tissue lymphoma and gastric cancer (GC). While this bacterium infects 50% of the world’s population, in Africa its prevalence reach as high as 80% as the infection is acquired during childhood. Risk factors for H. pylori acquisition have been reported to be mainly due to overcrowding, to have infected siblings or parent and to unsafe water sources. Despite this high H. pylori prevalence there still does not exist an African guideline, equivalent to the Maastricht V/Florence Consensus Report of the European Helicobacter and Microbiota Study Group for the management of this infection. In this continent, although there is a paucity of epidemiologic data, a contrast between the high prevalence of H. pylori infection and the low incidence of GC has been reported. This phenomenon is the so-called “African Enigma” and it has been hypothesized that it could be explained by environmental, dietary and genetic factors. A heterogeneity of data both on diagnosis and on therapy have been published. In this context, it is evident that in several African countries the increasing rate of bacterial resistance, mainly to metronidazole and clarithromycin, requires continental guidelines to recommend the appropriate management of H. pylori. The aim of this manuscript is to review current literature on H. pylori infection in Africa, in terms of prevalence, risk factors, impact on human health, treatment and challenges encountered so as to proffer possible solutions to reduce H. pylori transmission in this continent.

Helicobacter pylori Mutations Conferring Resistance to Fluoroquinolones and Clarithromycin among Dyspeptic Patients Attending a Tertiary Hospital, Tanzania

Objectives. Helicobacter pylori (H. pylori) isolates resistant to clarithromycin and quinolones are increasing worldwide. Data regarding the magnitude of H. pylori resistance are limited in developing countries. Here, we report the prevalence of mutations conferring resistance to clarithromycin and fluoroquinolones among dyspeptic patients attending a tertiary hospital, Tanzania. Methods. Between August 2014 and August 2016, patients undergoing upper gastrointestinal endoscopy at the Bugando Medical Centre were enrolled. Biopsies were taken for polymerase chain reaction (PCR) and sequencing to detect mutations conferring resistance to clarithromycin and fluoroquinolones. Results. A total of 208 nonrepetitive biopsies were examined of which 188 (90.4%) tested positive for H. pylori specific 23S rRNA PCR. Clarithromycin resistance mutations were detected in 54/188 (28.7%) of patients tested. The most frequently detected mutation was A2143G (30) followed by A2142G (20). Out of 131 nonrepetitive biopsies tested for fluoroquinolones resistance mutations, 77/131 (58.8%) were positive, with N87I (20) mutation being the most frequently detected mutation followed by A92T mutation which was detected in 16 samples. Conclusion. A significant proportion of dyspeptic patients attending tertiary hospital in Tanzania are infected with H. pylori strains harbouring clarithromycin or fluoroquinolones resistance mutations. Detection of more than 50% of strains with fluoroquinolones resistance mutations makes the H. pylori second line treatment questionable in our setting. There is a need of surveillance of H. pylori resistance patterns in Tanzania to provide data that can guide empirical treatment to reduce associated morbidity of H. pylori infections. The correlation between A92T fluoroquinolone mutation and phenotypic resistance requires further investigations.

Concurrent detection of cagA, vacA, sodB and hsp60 virulence genes and their relationship with clinical outcomes of disease in Helicobacter pylori isolated strains of southwest of Iran

BACKGROUND AND OBJECTIVES

Helicobacter pylori is a Gram-negative spiral-shaped bacterium that contaminates more than half of the world's inhabitants, and infection with this bacterium is associated with some gastric disorders. Also, 5% to 10% of H. pylori genes are specific to this bacterium and many bacterial virulence factors fall into this group. The cagA, vacA, sodB and hsp60 are among important virulence factors of H. pylori.

MATERIALS AND METHODS

A gastric biopsy specimen was taken from 341 gastric patients and cultivated on a Colombia agar plate, containing various antibiotics, such as vancomycin, amphotericin B, and trimethoprim & polymyxin B, and incubated for 3 to 10 days under microaerophilic conditions at 37°C. PCR was used to detect the ureC, cagA, vacA, sodB and hsp60 genes.

RESULTS

In this study, 131 isolates were identified as H. pylori. The prevalence of cagA, vacA, sodB and hsp60 were 74%, 100%, 92.4% and 96.2%, respectively. The correlation between the clinical forms of the disease and the virulence genes were analyzed by statistical tests and no significant correlation was found.

CONCLUSION

The obtained results are similar to some studies conducted in different parts of the world and is different in other cases. This discrepancy is due to the difference in the type of gastric disorders, sample size and methodology.

The magnitude of antibiotic resistance to Helicobacter pylori in Africa and identified mutations which confer resistance to antibiotics: systematic review and meta-analysis

Background

Worldwide Helicobacter pylori (H.pylori) treatment is of great challenge due to increased antibiotic resistance. The burden of H. pylori antibiotic resistance in Africa is high with unclear information regarding the real magnitude. This systematic review and meta-analysis was conducted to investigate the magnitude of H.pylori antibiotic resistance in Africa to gain insight of the extent of the problem among H.pylori naïve treatment patients.

Method

The search was performed in the academic databases, Embase, PubMed, Web of Science and Africa Wide Information. ProQuest Dissertation and Theses, Scopus, Ethos, Africa Index Medicus (WHO), BioMed Central Proceedings, BASE, British Library, Open grey, Library of Congress and the New York Academy of Grey Literature Report were additionally searched for grey literature. Published articles from Africa on H.pylori antibiotic resistance between 1986 and June 2017 were systematically reviewed to estimate the H. pylori extent of resistance to macrolides, quinolones, amoxicillin, tetracycline and metronidazole.

Results

In 26 articles a total of 2085 isolates were tested for metronidazole, 1530 for amoxicillin, 1277 for tetracycline, 1752 for clarithromycin and 823 for quinolones.The overall pooled proportion of H.pylori resistance to quinolones, clarithromycin, tetracycline, metronidazole and amoxicillin were: (17.4%, 95%CI 12.8 - 21.9), (29.2%, 95%CI:26.7-31.8), (48.7%, 95%CI: 44.5-52.9), (75.8%, 95% CI: 74.1-.77.4) and (72.6%, 95% CI: 68.6-76.6), respectively. The commonest mutation detected were A2143G (49/97) for clarithromycin, RdxA (41/56) for metronidazole and D87I (16/40) for quinolones.

Conclusion

Prevalence of metronidazole, clarithromycin, and amoxicillin resistance is high in developing world including Africa. This could impair the first line triple therapy of the H.pylori infection. There is a need of conducting surveillance of H.pylori susceptibility pattern in Africa for dual and triple resistance which can be used for the empirical treatment.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3099-4) contains supplementary material, which is available to authorized users.

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.

Point Mutations at gyrA and gyrB Genes of Levofloxacin-Resistant Helicobacter pylori Isolates in the Esophageal Mucosa from a Venezuelan Population

The treatment of Helicobacter pylori infection is complicated by antibiotic resistance. A high levofloxacin (LVX) resistance rate was previously demonstrated in H. pylori isolates from gastric mucosa (40%) and esophagus (19%) in individual hosts of a Venezuelan population. We aimed to assess the molecular mechanisms of LVX resistance and susceptibility in isolates from the gastroesophageal mucosa, by studying point mutations in the quinolone resistance-determining region of gyrA and gyrB genes. Sequencing of gyrA and gyrB genes (N = 120) helped to identify point mutations in 60 isolates (30 from antrum and 30 from esophagus) of five dyspeptic patients. Double (Asn87Thr and Asp91Asn) and single (Asn87Ile or Asn87Thr) mutations in the gyrA gene were identified in the esophageal mucosa. These mutations have been commonly found in the stomach. Occurrence of a single (Asn87Ile) mutation was associated with high resistance (minimum inhibitory concentration ≥ 32 μg/mL) to LVX. Only a single (Ser479Gly) mutation was found in the gyrB gene in both mucosae. One patient presented isolates with no mutations in the two genes studied. Isolates with the same mutation pattern in individual hosts revealed identical genetic profiles for these genes, confirming that isolates identified in the esophageal mucosa come from isolates colonizing the stomach. Helicobacter pylori resistance to LVX in the esophagus is related to double- and single-point mutations in gyrA and gyrB genes, such as those found in the stomach. Levofloxacin should be applied with caution, because its antibiotic effect on H. pylori is decreasing in Latin America, perhaps owing to high prescription rates.

Resistance mechanisms of Helicobacter pylori and its dual target precise therapy

Helicobacter pylori drug resistance presents a significant challenge to the successful eradication of this pathogen. To find strategies to improve the eradication efficacy of H. pylori, it is necessary to clarify the resistance mechanisms involved. The mechanisms of H. pylori drug resistance can be investigated from two angles: the pathogen and the host. A comprehensive understanding of the molecular mechanisms of H. pylori resistance based on both pathogen and host would aid the implementation of precise therapy, or ideally "dual target precise therapy" (bacteria and host-specific target therapy). In recent years, with increased understanding of the mechanisms of H. pylori resistance, the focus of eradication has shifted from disease-specific to patient-specific treatment. The implementation of "precision medicine" has also provided a new perspective on the treatment of infectious diseases. In this article, we systematically review current research on H. pylori drug resistance from the perspective of both the pathogen and the host. We also review therapeutic strategies targeted to pathogen and host factors that are aimed at achieving precise treatment of H. pylori.

GenoType® HelicoDR test in comparison with histology and culture for Helicobacter pylori detection and identification of resistance mutations to clarithromycin and fluoroquinolones

BACKGROUND

There are several methods for Helicobacter pylori infection diagnosis.

AIM

The efficacies of three methods for H. pylori identification directly from a biopsy were compared: histology, culture, and molecular GenoType® HelicoDR test.

MATERIALS & METHODS

Eighty-five triplicates of stomach antrum biopsies were obtained during gastroscopy procedures for culture, histology, and molecular assay. In addition, we performed molecular identification of genes encoding resistance to clarithromycin and fluoroquinolones.

RESULTS

The results have shown that the most specific method with the highest number of positive specimens was by molecular kit, compared to culture and histology (94.3%, 77.1%, and 71.4%, respectively). There was a higher rate of resistance mutations to clarithromycin than to fluoroquinolones (68.26% vs 20%). The most common mutations for clarithromycin and fluoroquinolones resistance were found in alleles A2143G and N87K, respectively. The highest rate of positive specimens was identified by the molecular.

DISCUSSION

GenoType HelicoDR kit (94.3%), which has several advantages: direct identification, strain resistance characterization, mixture of genotypes detection, and no transport or storage limitations; thus, it is an excellent epidemiological screening tool. This work has demonstrated a lower resistance rate to fluoroquinolones; it is possible that in the investigated geographic area treatment with fluoroquinolones may be preferable to clarithromycin. GenoType® HelicoDR test eliminates the need for culture performance and susceptibility tests for several common antibiotic agents and enables optimal and specific antibiotic treatment adjustment.

CONCLUSION

We recommend a combination of PCR assay and bacterial culture for a quick method of screening and more efficient identification of H. pylori strains and resistance patterns.

Helicobacter pylori Primary Antibiotic Resistance in 2015 in Morocco: A Phenotypic and Genotypic Prospective and Multicenter Study

Knowledge of local antibiotic resistance is crucial to adaption of the choice of effective empirical first-line treatment for Helicobacter pylori infection. The aim of this study was to evaluate, for the first time in Morocco, the prevalence of the primary resistance of H. pylori to clarithromycin, metronidazole, amoxicillin, levofloxacin, tetracycline, and rifamycin. We conducted a 1-year prospective study (2015), including 255 Moroccan patients referred for gastro-duodenal endoscopy to two hospitals of Rabat (Morocco) and never previously treated for H. pylori infection. Three gastric biopsies were collected: one for histology, one for culture, and one for molecular detection of H. pylori and the mutations in 23S rRNA genes that confer resistance to clarithromycin. Antimicrobial susceptibility testing was performed on isolated strains by Etest and disk diffusion methods. One hundred seventy-seven patients were infected (69.4%). The prevalence of primary resistances of H. pylori to clarithromycin was 29%, 40% to metronidazole, 0% to amoxicillin, tetracycline, and rifamycin, and 11% to levofloxacin. Only four isolates (2%) were resistant to both clarithromycin and metronidazole. The high level of primary clarithromycin resistance in the H. pylori strains infecting the Moroccan population leads us to recommend the abandonment of the standard clarithromycin-based triple therapy as a first-line treatment in Morocco and to prefer a concomitant quadruple therapy.

Molecular detection of Helicobacter pylori antibiotic resistance in stool vs biopsy samples

AIM

To compare (1) demographics in urea breath test (UBT) vs endoscopy patients; and (2) the molecular detection of antibiotic resistance in stool vs biopsy samples.

METHODS

Six hundred and sixteen adult patients undergoing endoscopy or a UBT were prospectively recruited to the study. The GenoType HelicoDR assay was used to detect Helicobacter pylori (H. pylori) and antibiotic resistance using biopsy and/or stool samples from CLO-positive endoscopy patients and stool samples from UBT-positive patients.

RESULTS

Infection rates were significantly higher in patients referred for a UBT than endoscopy (overall rates: 33% vs 19%; treatment-naïve patients: 33% vs 14.7%, respectively). H. pylori-infected UBT patients were younger than H. pylori-infected endoscopy patients (41.4 vs 48.4 years, respectively, P < 0.005), with a higher percentage of H. pylori-infected males in the endoscopy-compared to the UBT-cohort (52.6% vs 33.3%, P = 0.03). The GenoType HelicoDR assay was more accurate at detecting H. pylori infection using biopsy samples than stool samples [98.2% (n = 54/55) vs 80.3% (n =53/66), P < 0.005]. Subset analysis using stool and biopsy samples from CLO-positive endoscopy patients revealed a higher detection rate of resistance-associated mutations using stool samples compared to biopsies. The concordance rates between stool and biopsy samples for the detection of H. pylori DNA, clarithromycin and fluoroquinolone resistance were just 85%, 53% and 35%, respectively.

CONCLUSION

Differences between endoscopy and UBT patients provide a rationale for non-invasive detection of H. pylori antibiotic resistance. However, the GenoType HelicoDR assay is an unsuitable approach.

Validation of a High-Throughput Multiplex Genetic Detection System for Helicobacter pylori Identification, Quantification, Virulence, and Resistance Analysis

Helicobacter pylori (H. pylori) infection is closely related to various gastroduodenal diseases. Virulence factors and bacterial load of H. pylori are associated with clinical outcomes, and drug-resistance severely impacts the clinical efficacy of eradication treatment. Existing detection methods are low-throughput, time-consuming and labor intensive. Therefore, a rapid and high-throughput method is needed for clinical diagnosis, treatment, and monitoring for H. pylori. High-throughput Multiplex Genetic Detection System (HMGS) assay was established to simultaneously detect and analyze a set of genes for H. pylori identification, quantification, virulence, and drug resistance by optimizing the singlet-PCR and multiple primers assay. Twenty-one pairs of chimeric primers consisted of conserved and specific gene sequences of H. pylori tagged with universal sequence at the 5' end were designed. Singlet-PCR assay and multiple primers assay were developed to optimize the HMGS. The specificity of HMGS assay was evaluated using standard H. pylori strains and bacterial controls. Six clinical isolates with known genetic background of target genes were detected to assess the accuracy of HMGS assay. Artificial mixed pathogen DNA templates were used to evaluate the ability to distinguish mixed infections using HMGS assay. Furthermore, gastric biopsy specimens with corresponding isolated strains were used to assess the capability of HMGS assay in detecting biopsy specimens directly. HMGS assay was specific for H. pylori identification. HMGS assay for H. pylori target genes detection were completely consistent with the corresponding genetic background. Mixed infection with different drug-resistant isolates of H. pylori could be distinguished by HMGS assay. HMGS assay could efficiently diagnose H. pylori infection in gastric biopsy specimens directly. HMGS assay is a rapid and high throughput method for the simultaneous identification and quantification of H. pylori, analysis of virulence and drug resistance in both isolated strains and biopsy specimens. It could also be used to distinguish the mixed infection with different resistant genotype strains. Furthermore, HMGS could detect H. pylori infection in gastric biopsy specimens directly.

Detection of Helicobacter pylori resistance to clarithromycin and fluoroquinolones in Brazil: A national survey

AIM

To evaluate bacterial resistance to clarithromycin and fluoroquinolones in Brazil using molecular methods.

METHODS

The primary antibiotic resistance rates of Helicobacter pylori (H. pylori) were determined from November 2012 to March 2015 in the Southern, South-Eastern, Northern, North-Eastern, and Central-Western regions of Brazil. Four hundred ninety H. pylori patients [66% female, mean age 43 years (range: 18-79)] who had never been previously treated for this infection were enrolled. All patients underwent gastroscopy with antrum and corpus biopsies and molecular testing using GenoType HelicoDR (Hain Life Science, Germany). This test was performed to detect the presence of H. pylori and to identify point mutations in the genes responsible for clarithromycin and fluoroquinolone resistance. The molecular procedure was divided into three steps: DNA extraction from the biopsies, multiplex amplification, and reverse hybridization.

RESULTS

Clarithromycin resistance was found in 83 (16.9%) patients, and fluoroquinolone resistance was found in 66 (13.5%) patients. There was no statistical difference in resistance to either clarithromycin or fluoroquinolones (P = 0.55 and P = 0.06, respectively) among the different regions of Brazil. Dual resistance to clarithromycin and fluoroquinolones was found in 4.3% (21/490) of patients. The A2147G mutation was present in 90.4% (75/83), A2146G in 16.9% (14/83) and A2146C in 3.6% (3/83) of clarithromycin-resistant patients. In 10.8% (9/83) of clarithromycin-resistant samples, more than 01 mutation in the 23S rRNA gene was noticed. In fluoroquinolone-resistant samples, 37.9% (25/66) showed mutations not specified by the GenoType HelicoDR test. D91N mutation was observed in 34.8% (23/66), D91G in 18.1% (12/66), N87K in 16.6% (11/66) and D91Y in 13.6% (9/66) of cases. Among fluoroquinolone-resistant samples, 37.9% (25/66) showed mutations not specified by the GenoType HelicoDR test.

CONCLUSION

The H. pylori clarithromycin resistance rate in Brazil is at the borderline (15%-20%) for applying the standard triple therapy. The fluoroquinolone resistance rate (13.5%) is equally concerning.

A high-throughput multiplex genetic detection system for Helicobacter pylori identification, virulence and resistance analysis

AIM

We established a high-throughput multiplex genetic detection system (HMGS) for identification of Helicobacter pylori with concomitant analysis of virulence and drug resistance.

MATERIALS & METHODS

Confirmed 132 H. pylori cultures from gastric biopsies were screened by 20-gene site-HMGS, sequencing and E-test.

RESULTS

HMGS was highly sensitive and specific for H. pylori identification. Concordance rate between HMGS and sequencing averaged 94.5% (virulence genes) and 97.3% (resistance genes). Observed resistance rates to four mainstream antibiotics were high, except for amoxicillin. Significant association between virulence genotype and risks for specific gastrointestinal diseases was found for five genes. Metronidazole resistance in peptic ulcer patients was significantly higher.

CONCLUSION

HMGS is an effective method for H. pylori identification and analysis of virulence and drug resistance.

Detection of Helicobacter pylori and the genotypes of resistance to clarithromycin and the heterogeneous genotype to this antibiotic in biopsies obtained from symptomatic children

The aim of this study was to use a commercially available kit (GenoType® HelicoDR; Hain Life Science, Germany) to detect Helicobacter pylori infection and clarithromycin resistance genotype in biopsies obtained from symptomatic children.

RESULTS

111 out of 136 (81.6%) biopsies were H. pylori positive by genotype: 47 (42.3%) showed wild-type genotype, 53 resistant genotype (47.7%) and 11 heterogeneous genotype (9.9%). Culture was negative in 27 out of the 111 genotyped biopsies. Mutation A2143G (87.5%), followed by A2142G (7.5%) and double mutant A2142C-A2143G (5%) were found. The 11 heterogeneous genotype biopsies showed wild-type plus A2143G in 9 and plus A2142G in 2.

CONCLUSIONS

This kit is a rapid, culture-independent method for routine application in biopsies from the pediatric population that allows detection of clarithromycin resistance and heterogeneous genotypes. It is important to know the clinical impact of infection with this type of strains as well as the role in treatment success.

Molecular Approaches to Identify Helicobacter pylori Antimicrobial Resistance

Antimicrobial susceptibility testing is needed to adapt Helicobacter pylori treatment to obtain the best results. Beside the standard phenotypic methods, molecular methods are increasingly used. The value of these molecular tests is that they are quick, independent of the transport conditions, easy to standardize, and commercial kits are available. In this article, these methods are reviewed, focusing on the determination of H pylori resistance to macrolides and fluoroquinolones, and mentioning also the methods used for tetracycline and rifampin.

Diagnosis of Helicobacter pylori infection

The present manuscript focuses on the new information that was published in the field of diagnosis of Helicobacter pylori this past year. While there is little news about the invasive tests, more data are coming concerning the endoscopic features of H. pylori infection. Major efforts were also done to improve molecular detection of the mutations involved in antibiotic resistance. New antibody-based tests (stool antigen test or indirect antibody tests) were also developed.

How antibiotic resistances could change Helicobacter pylori treatment: A matter of geography?

Therapeutic management of Helicobacter pylori (H. pylori) remains an unsolved issue. Indeed, no therapeutic regimen is able to cure the infection in all treated patients, and in many the infection persists despite the administration of several consecutive standard therapies. Although antibiotic resistance reports describe alarming results, the outcome of therapeutic regimens does not seem to parallel this scenario in most cases, since a successful performance is often reached in more than 80% of cases. However, the phenomenon of increasing antibiotic resistance is being closely studied, and the results show controversial aspects even in the same geographic area. For the continents of Europe, America, Asia, Africa, and Oceania, minimal and maximal values of resistance to the main antibiotics (clarithromycin, amoxicillin, metronidazole, and levofloxacin) feature wide ranges in different countries. The real enigma is therefore linked to the several different therapeutic regimens, which show results that often do not parallel the in vitro findings even in the same areas. A first aspect to be emphasized is that some regimens are limited by their use in very small geographic districts. Moreover, not all therapeutic trials have considered bacterial and host factors affecting the therapeutic outcome. The additional use of probiotics may help to reduce adverse events, but their therapeutic impact is doubtful. In conclusion, the “ideal therapy”, paradoxically, appears to be a “utopia”, despite the unprecedented volume of studies in the field and the real breakthrough in medical practice made by the discovery and treatment of H. pylori. The ample discrepancies observed in the different areas do not encourage the development of therapeutic guidelines that could be valid worldwide. On these bases, one of the main challenges for the future might be identifying a successful solution to overcome antibiotic resistances. In this context, geography must be considered a relevant matter.

Helicobacter pylori infection: selected aspects in clinical management

PURPOSE OF REVIEW

This review focuses on new aspects of recently published guidelines for the management of Helicobacter pylori infection as well as progress in diagnostic tests and treatment regimens. We also discuss new strategies for gastric cancer prevention.

RECENT FINDINGS

The general recommendation to treat H. pylori infection whenever diagnosed still faces resistance for reasons that are pertinent to the diversity of related clinical outcomes and to the complexity of eradication regimens. Thus, new updated guidelines for the management of H. pylori infection have been released in several continents. Progress has been made in molecular diagnostic tests for the detection of antibiotic resistance and serological tests for the detection of advanced gastric atrophic changes. Effective quadruple therapies in various combinations of 'traditional drugs' have been introduced with sequential or concomitant order of administration. Moreover, traditional drugs in a new galenic formulation have been introduced to overcome increasing H. pylori antibiotic resistance. Effective strategies for gastric cancer prevention have been adopted in some countries with high gastric cancer incidence, and have successfully contributed to lower the gastric cancer incidence. A screen-and-treat strategy for individuals at increased risk for gastric cancer needs to be further explored also in areas with low/moderate incidence of gastric cancer.

SUMMARY

New guidelines share many universal similarities across countries but respect and emphasize specific needs and requirements in individual communities. Various combinations of traditional drugs have been successfully introduced to overcome the increasing H. pylori antibiotic resistance. Gastric cancer prevention by a screen and treat strategy showed promising results.