Detection of Helicobacter pylori DNA sequences in gastric biopsy samples to refine the diagnosis and therapy

Diagnostic Testing Accuracy for Helicobacter pylori Infection among Adult Patients with Dyspepsia in Cuba's Primary Care Setting

Evidence of the effectiveness of the tests used to diagnose Helicobacter pylori (H. pylori) in primary healthcare is limited. This cross-sectional study aims to assess the accuracy of tests used for to diagnose H. pylori infection in primary care patients and its relationship with gastroduodenal pathologies. Over 12 months, 173 primary care patients with dyspeptic symptoms were referred for upper gastrointestinal endoscopy to obtain gastric biopsies, and venous blood was extracted from them. H. pylori infection was detected using a rapid urease test (RUT), real-time polymerase chain reaction (RT-PCR), H. pylori-IgG ELISA, and Western blot (WB). The culture and histological findings were used as the reference standard for H. pylori infection. H. pylori prevalence was 50%. There were no significant differences between men and women overall or by age group. The presence of H. pylori was associated with chronic moderate gastritis and its absence with chronic inactive gastritis, as well as the combination of gastritis and gastric lesions (p < 0.05). RUT and ELISA H. pylori -IgG tests showed the highest overall performance (accuracy 98.9% and 84.4%), followed by WB and RT-PCR (accuracy 79.3% and 73.9%). These findings support the notion that combined invasive and noninvasive methods, such as RUT and H. pylori-IgG ELISA, can be a primary diagnostic screening tool for detecting H. pylori among adult dyspeptic patients in Cuba's primary care setting.

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

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

Effect of metronidazole resistance on Helicobacter pylori eradication regimens

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Efficacy of immunohistochemical staining in detecting <em>Helicobacter pylori</em> in Saudi patients with minimal and atypical infection

Gastric Helicobacter pylori infection is diagnosed based on histopathological evaluation of gastric mucosal biopsies, urease test, urea breath test, H. pylori culturing, or direct detection using polymerase chain reaction (PCR). This study aimed to evaluate the efficacy of immunohistochemical (IHC) staining in detecting H. pylori in gastric biopsies from patients with chronic gastritis and minimal or atypical infection. Gastric biopsies from 50 patients with chronic gastritis were subjected to routine haematoxylin and eosin (H-E), modified Giemsa, and IHC staining. The results of staining were compared with those of quantitative real-time PCR (qRT-PCR). The qRT-PCR analysis identified 32 (64%) H. pylori-positive cases, whereas IHC, H-E, and modified Giemsa staining identified 29 (58%), 27 (54%), and 21 (42%) positive cases. The sensitivity of IHC staining (87.50%) was higher than that of H-E (59.38%) and modified Giemsa (43.75%) staining. The specificity of H-E, modified Giemsa, and IHC staining was 55.56%, 61.11%, and 94.44%, respectively. IHC staining exhibited the highest diagnostic accuracy (90%), followed by H-E (58%) and modified Giemsa (50%) staining. Active gastritis, intestinal metaplasia, and lymphoid follicles were detected in 32 (64%), 4 (8%), and 22 (44%) cases, respectively, and all of these cases were H. pylori positive. In contrast to routine H-E and modified Giemsa staining, IHC allows for the accurate H. pylori detection in cases with minimal or atypical infection. Moreover, IHC can be an alternative diagnostic method to qRT-PCR for detection of H. pylori in such cases.

The Puzzle of Coccoid Forms of Helicobacter pylori: Beyond Basic Science

Helicobacter pylori (H. pylori) may enter a non-replicative, non-culturable, low metabolically active state, the so-called coccoid form, to survive in extreme environmental conditions. Since coccoid forms are not susceptible to antibiotics, they could represent a cause of therapy failure even in the absence of antibiotic resistance, i.e., relapse within one year. Furthermore, coccoid forms may colonize and infect the gastric mucosa in animal models and induce specific antibodies in animals and humans. Their detection is hard, since they are not culturable. Techniques, such as electron microscopy, polymerase chain reaction, loop-mediated isothermal amplification, flow cytometry and metagenomics, are promising even if current evidence is limited. Among the options for the treatment, some strategies have been suggested, such as a very high proton pump inhibitor dose, high-dose dual therapy, N-acetycysteine, linolenic acid and vonoprazan. These clinical, diagnostic and therapeutic uncertainties will represent fascinating challenges in the future.

Primary antibiotic resistance of Helicobacter pylori strains among adults and children in a tertiary referral centre in Lithuania

The study evaluated primary antibiotic resistance of Helicobacter pylori within the period 2013-2015 and trends of antibiotic consumption over the last decade in Lithuania; 242 adults and 55 children were included in the study. E-tests were performed for amoxicillin, metronidazole, clarithromycin, ciprofloxacin, rifampicin and tetracycline. The presence of H. pylori and clarithromycin resistance was additionally tested by PCR. Helicobacter pylori culture was positive in 67 of 242 (28%) adult and in 12 of 55 (21.8%) children samples. Resistance rates among adults by E-tests were as follows: metronidazole - 32.8% (95% confidence interval (CI): 22.7-44.7%), ciprofloxacin - 7.5% (95% CI: 3.2-16.3%), rifampicin - 7.5% (95% CI: 3.2-16.3%), amoxicillin - 0%, whereas resistance rates in children were as follows: metronidazole - 25% (95% CI: 8.9-53.2%), rifampicin - 8.3% (CI: 1.5-35.4%), amoxicillin and ciprofloxacin - 0%. Accumulated clarithromycin resistance rates by E-tests and PCR were 8.2% (95% CI: 4.1-16.0%) in adults and 17.7% (95% CI: 6.2-41.0%) in children. Total use of macrolides and lincosamides in Lithuania increased from 1.26 to 1.86 defined daily dose (DDD)/1000 inhabitants/day among adults, while it has doubled from 1.10 to 2.22 DDD/1000/children/day in children within 2003-2015. There are no significant changes in the susceptibility of H. pylori to the most widely used antibiotics in adults over the last years in Lithuania; however, clarithromycin resistance among children exceeds 15% and mandates further larger-scale studies in paediatric population.

Noninvasive molecular analysis of Helicobacter pylori: Is it time for tailored first-line therapy?

The main problem of Helicobacter pylori (H. pylori) infection management is linked to antibiotic resistances. This phenomenon has grown in the last decade, inducing a dramatic decline in conventional regimen effectiveness. The causes of resistance are point mutations in bacterial DNA, which interfere with antibiotic mechanism of action, especially clarithromycin and levofloxacin. Therefore, international guidelines have recently discouraged their use in areas with a relevant resistance percentage, suggesting first-line schedules with expected high eradication rates, i.e., bismuth containing or non-bismuth quadruple therapies. These regimens require the daily assumption of a large number of tablets. Consequently, a complete adherence is expected only in subjects who may be motivated by the presence of major disorders. However, an incomplete adherence to antibiotic therapies may lead to resistance onset, since sub-inhibitory concentrations could stimulate the selection of resistant mutants. Of note, a recent meta-analysis suggests that susceptibility tests may be more useful for the choice of first than second-line or rescue treatment. Additionally, susceptibility guided therapy has been demonstrated to be highly effective and superior to empiric treatments by both meta-analyses and recent clinical studies. Conventional susceptibility test is represented by culture and antibiogram. However, the method is not available everywhere mainly for methodology-related factors and fails to detect hetero-resistances. Polymerase chain reaction (PCR)-based, culture-free techniques on gastric biopsy samples are accurate in finding even minimal traces of genotypic resistant strains and hetero-resistant status by the identification of specific point mutations. The need for an invasive endoscopic procedure has been the most important limit to their spread. A further step has, moreover, been the detection of point mutations in bacterial DNA fecal samples. Few studies on clarithromycin susceptibility have shown an overall high sensitivity and specificity when compared with culture or PCR on gastric biopsies. On these bases, two commercial tests are now available although they have shown some controversial findings. A novel PCR method showed a full concordance between tissue and stool results in a preliminary experience. In conclusion, despite poor validation, there is increasing evidence of a potential availability of noninvasive investigations able to detect H. pylori resistances to antibiotics. These kinds of analysis are currently at a very early phase of development and caution should be paid about their clinical application. Only further studies aimed to evaluate their sensitivity and specificity will afford novel data for solid considerations. Nevertheless, noninvasive molecular tests may improve patient compliance, time/cost of infection management and therapeutic outcome. Moreover, the potential risk of a future increase of resistance to quadruple regimens as a consequence of their use on large scale and incomplete patient adherence could be avoided.

Helicobacter pylori DNA isolation in the stool: an essential pre-requisite for bacterial noninvasive molecular analysis

PURPOSE

Real-time polymerase chain reaction (RT-PCR) is a widely used technique for bacterial and viral infection diagnosis. Herein, we report our preliminary experience in retrieving H. pylori genetic sequences in stools and analyzing genotypic clarithromycin resistance by RT-PCR (noninvasive), with the aim of comparing this procedure with that performed on biopsy samples (invasive).

MATERIALS AND METHODS

After 'in vitro' demonstration of H. pylori DNA detection from pure and stool-mixed bacteria, 52 consecutive patients at the first diagnosis of infection were investigated. DNA was extracted from biopsy tissue and stool samples (THD® Fecal Test, Italy). RT-PCR was performed to detect 23S rRNA encoding bacterial subunit gene and search A2143G, A2142C, A2142G point mutations for clarithromycin resistance assessment.

RESULTS

RT-PCR showed H. pylori positive DNA in all infected patients with full concordance between tissue and stool detection (100%). We found A2143G mutation in 10 (19.2%), A2142G in 4 (7.7%) and A2142C in 5 (9.6%) patients; there was a full agreement between biopsy and fecal samples. A2143G was found in all the four A2142G positive cases and in three out of the five A2142C positive strains. Overall clarithromycin resistance rate in our series was 23%.

CONCLUSIONS

Despite the need of confirmation on large sample, stool RT-PCR analysis could represent a feasible tool to detect H. pylori DNA sequences and antibiotic resistance point mutations. As compared to tissue molecular analysis, this technique is noninvasive, with potential advantages such as improvement of patient compliance, reduction of diagnostic procedure time/cost and improvement of therapeutic outcome.