Comparison of the clinical feasibility of three rapid urease tests in the diagnosis of Helicobacter pylori infection

Anthocyanin-rich black carrot (Daucus carota ssp. sativus var. atrorubens Alef.) and red cabbage (Brassica oleracea) extracts incorporated biosensor for colorimetric detection of Helicobacter pylori with color image processing

In this work, we developed novel colorimetric biosensors consisting of anthocyanin-rich either black carrot (Daucus carota ssp. sativus var. atrorubens Alef.) or red cabbage (Brassica oleracea) extracts for rapid, sensitive, and economic detection of Helicobacter pylori (H. pylori). We comparatively prepared two test solutions as biosensors including anthocyanin-rich black carrot extract (Anth@BCE) and red cabbage extract (Anth@RCE), both of which fixed to pH 2.5 and investigated their colorimetric responses based on electronic structure and electron density of anthocyanins. We successfully used anthocyanin-rich BCE and RCE as natural pH indicators in detection of H. pylori and introduced their advantages like non-toxicity, easy accessibility, and high stability compared to synthetic indicators. The BCE and RCE tests gave the best color change in the presence of 103 CFU/mL (at 60 min) and 104 CFU/mL (at 75 min) H. pylori suspensions prepared in an artificial gastric fluid. The limit of detection was down to 10 CFU/mL for RCE and BCE tests by increasing incubation time (≥ 5 h). We further made an additional study that color differences in the colorimetric responses observed by naked eyes were supported by digital image processing with RGB (Red Green Blue) and Delta-E (ΔE) analysis. It is confirmed that results evaluated by naked eyes and digital image processing are well consistent with each other. These findings proposed that these colorimetric tests can be implemented to pH dependent detection of various microorganisms and can be effectively transferred from laboratory work to clinics in the near future.

Personalized Approach in Eradication of Helicobacter pylori Infection

The increase in antibiotic resistance to Helicobacter pylori (H. pylori) is associated with a decrease in the effectiveness of eradication therapy. Although some success has been achieved by adjusting therapeutic regimens according to local data on resistance to certain antibiotics, a new approach is needed to ensure a better therapeutic response. Tailored therapy, based on sensitivity tests to antibiotics, is increasingly proving to be a superior therapeutic option, even as a first-line therapy. Moreover, the recently published Maastricht VI guidelines emphasize utilizing a susceptibility-guided strategy in respect to antibiotic stewardship as the first choice for eradication therapy. In addition, polymerase chain reaction (PCR) technology is becoming a standard tool in the diagnosis of H. pylori infections through non-invasive testing, which further optimizes the eradication process. We provide a review regarding the current position of the individualized approach in eradication therapy and its future prospects. Based on novel understandings, the personalized approach is an effective strategy to increase the successful eradication of H. pylori infections.

An Ultrasensitive PCR-Based CRISPR-Cas13a Method for the Detection of Helicobacter pylori

The rapid and simple detection of Helicobacter pylori (H. pylori) is essential for its clinical eradication. Although various methods for detecting H. pylori have been well established, such as endoscopy in combination with histology or culture, rapid urease test (RUT) and molecular tests using clinical specimens, it is of great importance to develop an ultrasensitive and accurate nucleic acid detection platform and apply it to identify H. pylori. To meet these demands, a novel method based on PCR and CRISPR-Cas13a, called PCR-Cas13a, was developed and validated using the DNA of 84 clinical strains and 71 clinical specimens. PCR primers for the pre-amplification of conservative sequence and CRISPR RNA (crRNA) for the detection of specific sequence were designed according to the principle. The designed primers and crRNA were specific to H. pylori, and the assay showed a high degree of specificity compared with other common pathogens. Our detection system can screen H. pylori with a limit of 2.2 copies/μL within 30 mins after PCR amplification. Using a coincidence analysis with traditional methods, our method exhibited 100% accuracy for the detection of H. pylori. Furthermore, its diagnostic performance was compared, in parallel with a q-PCR. The PCR-Cas13a demonstrates 98% sensitivity and 100% specificity. Moreover, our approach had a lower limit of detection (LOD) than q-PCR. Herein, we present a diagnostic system for the highly sensitive screening of H. pylori and distinguish it from other pathogens. All the results demonstrated that this PCR-based CRISPR assay has wide application prospects for the detection of H. pylori and other slow-growth pathogens.

Field detection of urease and carbonic anhydrase activity using rapid and economical tests to assess microbially induced carbonate precipitation

Microbial precipitation of calcium carbonate is a widespread environmental phenomenon that has diverse engineering applications, from building and soil restoration to carbon sequestration. Urease-mediated ureolysis and CO2 (de)hydration by carbonic anhydrase (CA) are known for their potential to precipitate carbonate minerals, yet many environmental microbial community studies rely on marker gene or metagenomic approaches that are unable to determine in situ activity. Here, we developed fast and cost-effective tests for the field detection of urease and CA activity using pH-sensitive strips inside microcentrifuge tubes that change colour in response to the reaction products of urease (NH3 ) and CA (CO2 ). The urease assay proved sensitive and useful in the field to detect in situ activity in biofilms from a saline lake, a series of calcareous fens, and ferrous springs, finding relatively high urease activity in lake samples. Incubations of lake microbes with urea resulted in significantly higher CaCO3 precipitation compared to incubations with a urease inhibitor, showing that the rapid assay indicated an on-site active metabolism potentially mediating carbonate precipitation. The CA assay, however, showed less sensitivity compared to the urease test. While its sensitivity limits its utility, the assay may still be useful as a preliminary indicator given the paucity of other means for detecting CA activity in the field. Field urease, and potentially CA, activity assays complement molecular approaches and facilitate the search for carbonate-precipitating microbes and their in situ activity, which could be applied toward agriculture, engineering and carbon sequestration technologies.

Review of current diagnostic methods and advances in Helicobacter pylori diagnostics in the era of next generation sequencing

Helicobacter pylori (H. pylori) infection is highly prevalent in the human population and may lead to severe gastrointestinal pathology including gastric and duodenal ulcers, mucosa associated tissue lymphoma and gastric adenocarcinoma. In recent years, an alarming increase in antimicrobial resistance and subsequently failing empiric H. pylori eradication therapies have been noted worldwide, also in many European countries. Therefore, rapid and accurate determination of H. pylori’s antibiotic susceptibility prior to the administration of eradication regimens becomes ever more important. Traditionally, detection of H. pylori and its antimicrobial resistance is done by culture and phenotypic drug susceptibility testing that are cumbersome with a long turn-around-time. Recent advances in diagnostics provide new tools, like real-time polymerase chain reaction (PCR) and line probe assays, to diagnose H. pylori infection and antimicrobial resistance to certain antibiotics, directly from clinical specimens. Moreover, high-throughput whole genome sequencing technologies allow the rapid analysis of the pathogen’s genome, thereby allowing identification of resistance mutations and associated antibiotic resistance. In the first part of this review, we will give an overview on currently available diagnostic methods for detection of H. pylori and its drug resistance and their implementation in H. pylori management. The second part of the review focusses on the use of next generation sequencing technology in H. pylori research. To this end, we conducted a literature search for original research articles in English using the terms “Helicobacter”, “transcriptomic”, “transcriptome”, “next generation sequencing” and “whole genome sequencing”. This review is aimed to bridge the gap between current diagnostic practice (histology, rapid urease test, H. pylori culture, PCR and line probe assays) and new sequencing technologies and their potential implementation in diagnostic laboratory settings in order to complement the currently recommended H. pylori management guidelines and subsequently improve public health.

The Diagnostic Tests for Detection of Helicobacter pylori Infection

Helicobacter pylori causes one of the most common infections in human populations. The role of this bacterium in chronic gastritis, gastric ulcer, gastric cancer, as well as extra-digestive diseases such as ischemic heart disease and chronic obstructive pulmonary diseases, is well known. Prevention and control of these diseases can occur by early diagnosis and eradication of H. pylori infection. At present, different methods have been established to detect H. pylori infection. The biopsy-based tests, which are known as invasive methods, such as rapid urease test and histology, have the highest specificity among the others. Similarly, culture of biopsy samples is used for diagnosis of H. pylori infection. It has a high specificity value, and also allows us to perform antibiotic sensitivity testing. On the contrary, polymerase chain reaction and other molecular methods have good sensitivity and specificity, and can be used for detection of H. pylori infection, its virulence factors, and eradication success after treatment. While serological tests are more appropriate for epidemiological studies, their main weakness for clinical use is low specificity. Overall, specificity and sensitivity, cost, usefulness, and limitation of tests should be considered for selection of detection methods of H. pylori in each country.

Presence of Helicobacter pylori and Campylobacter ureolyticus in the oral cavity of a Northern Thailand population that experiences stomach pain

Objective: To investigate oral diseases and microbiological conditions, such as the presence of ureolytic bacteria in dental plaque, in relation to experience of stomach pain in a remote adult Asian population. Methods: Ninety-three adults, 40-60-years old, from the Karen Hill tribe in Northern Thailand with no regular access to dental care were examined. Clinical registrations were performed and interproximal gingival plaque samples were collected and analyzed with the checkerboard (CKB) method for the presence of 14 oral bacterial species. Results: A number of 61 subjects reported daily stomach pain while 32 subjects had no symptoms from the stomach. The subjects with stomach pain had fewer remaining teeth (p < 0.05), higher caries experience (p < 0.05) and less BoP (p < 0.01). Most of the bacterial species were clustered statistically in three factors in a factor analysis, which together explained 65% of the microbiological variance. Factor 1, explaining 43.0% of the variance, was statistically associated with stomach pain (p < 0.001). Conclusions: The interproximal plaque/biofilm in adults of the study population showed a common presence of two gastrointestinal pathogens H. pylori and C. ureolyticus. The study also indicates for the first time a potential association between C. ureolyticus and stomach pain.

Intranasal Helicobacter pylori infection in patients with chronic rhinosinusitis with polyposis

Objective

To determine the prevalence of Helicobacter pylori infection in nasal biopsy specimens from patients with chronic rhinosinusitis with polyposis versus control patients, and to assess the correlations between H pylori infection identified in the nasal tissue and patients’ sociodemographic data and reflux-related symptoms and signs.

Methods

Nasal biopsy samples were taken from 75 adult patients who underwent nasal surgery for chronic rhinosinusitis with polyposis (clinical group, n = 45) and a deviated septum (control group, n = 30). H pylori infection was identified using histochemical and rapid urease tests.

Results

The prevalence of intranasal H pylori infection was significantly higher in the clinical group (28.9 per cent) compared to the control group (3.3 per cent) (p = 0.005). A significant yet weak association was found between positive H pylori status and laryngopharyngeal reflux related hypertrophy of the posterior commissure of the larynx. No other correlations reached statistical significance.

Conclusion

H pylori infection is potentially related to chronic rhinosinusitis with polyposis. Further research is needed to clarify the role of H pylori as a risk factor for the development of sinonasal diseases and to examine its link with laryngopharyngeal reflux.

Diagnosis of Helicobacter pylori infection : A short review

Helicobacter pylori infections represent an important factor in the pathogenesis of chronic gastritis, peptic ulcer, MALT lymphoma and gastric adenocarcinoma. The recently published Maastricht V/Florence consensus report indicated that the urea breath test using 13 C urea still remains the best non-invasive test to diagnose H. pylori infections with high sensitivity and specificity. Among the stool antigen tests, the ELISA monoclonal antibody test is a rational option. Effective therapy should be based only on susceptibility testing in regions with documented high clarithromycin resistance (>15%). Advanced high-resolution endoscopic technologies enable increased diagnostic accuracy for detection of H. pylori infections.

Multicenter Evaluation of Helicobacter pylori IgG Antibody Seroprevalence Among Patients Seeking Clinical Care in the US

BACKGROUND

Current American College of Gastroenterology (ACG) guidelines suggest that Helicobacter pylori serologic testing may be helpful to rule out H. pylori in areas with low disease prevalence. However, even in low prevalence regions, the positive predictive value of a positive serologic result remains low. Additionally, both the ACG and the American Gastroenterological Association recommend that this noninvasive testing be avoided entirely for patients 55 years and older.

METHODS

The objective of this multicenter retrospective study was to assess H. pylori seroprevalence rates among symptomatic patients and serologic test utilization at the local, state, and national level. Submitted specimens were presumed to be collected from patients with upper gastrointestinal symptoms suspicious for an H. pylori etiology. Results for H. pylori IgG serologic tests performed between 2005 and 2014 were collected from 5 medical centers. Data were evaluated in the context of professional practice guidelines, with a focus on patients ages 55 years and older.

RESULTS

Nationwide seropositivity among symptomatic individuals is approximately 25%, and 4 of 5 centers reported decreasing seropositivity rates over this 10-year period. State-specific seropositivity among symptomatic patients ranged from 12.4% in the state of Washington to 33.9% in Mississippi.

CONCLUSIONS

We demonstrate that for 48 states >25% of all H. pylori serologic testing was performed in individuals ≥55 years. Despite recommendations to avoid serologic evaluation for H. pylori infection, this study indicates that serology continues to be used at high rates across age-groups.

MUC1 and MUC5AC Acting on Helicobacter pylori-Related Deficiency and Solid Syndrome of Spleen and Stomach

To investigate the relationship of MUC1, MUC5AC, and the syndrome of spleen and stomach, 109 subjects (34 peptic ulcer (PU), 62 chronic gastritis (CG), and 13 healthy volunteers (CON)) were included. All the subjects included were surveyed with questionnaire to classify them into damp-heat syndrome of spleen and stomach (DHSS), spleen-qi deficiency syndrome (SQD), and CON, examined by gastric endoscope, and biopsied. Rapid urease and methylene blue staining (MBS) were performed on every subject to diagnose for Helicobacter pylori (Hp) infection, and both were defined as Hp-positive. Hematoxylin and eosin (HE) staining was performed on every specimen to explore the histomorphology, inflammatory degree, and inflammatory activity of different groups; then Elivision™ plus kit was used to test the expression of MUC1 and MUC5AC. All the results of digital images were reviewed by two experts blindly. The inflammatory degree with Hp infection was higher than those uninfected or CON, but no significant difference was found between DHSS and SQD. And the expressions of MUC5AC with positive Hp was higher than those with negative Hp or CON regardless of the deficiency and solid syndrome of spleen-stomach but not for MUC1. We speculate that the deficiency and solid syndrome of spleen-stomach is a condition like Tai Ji symbol of dynamic equilibrium, showing the higher expression of MUC5AC but no change of MUC1 in the circumstance of Hp infection.

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori.

OBJECTIVES

To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started.

SEARCH METHODS

We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as 13C or 14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities.

MAIN RESULTS

We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons.

AUTHORS' CONCLUSIONS

In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions.

Helicobacter pylori urease for diagnosis of Helicobacter pylori infection: A mini review

The stomach contents contain of both acid and proteolytic enzymes. How the stomach digests food without damaging itself remained a topic of investigation for decades. One candidate was gastric urease, which neutralized acid by producing ammonia from urea diffusing from the blood and potentially could protect the stomach. Discovery that gastric urease was not mammalian resulted in a research hiatus until discovery that gastric urease was produce by Helicobacter pylori which caused gastritis, peptic ulcer and gastric cancer. Gastric urease allows the organism to colonize the acidic stomach and serves as a biomarker for the presence of H. pylori. Important clinical tests for H. pylori, the rapid urease test and urea breath test, are based on gastric urease. Rapid urease tests use gastric biopsies or mucus placed in a device containing urea and an indicator of pH change, typically phenol red. Urea breath tests measure the change in isotope enrichment of ¹³C- or ¹⁴CO₂ in breath following oral administration of labeled urea. The urea breath test is non-invasive, convenient and accurate and the most widely used test for non-invasive test for detection of active H. pylori infection and for confirmation of cure after eradication therapy.

A multicenter prospective study on the diagnostic performance of a new liquid rapid urease test for the diagnosis of Helicobacter pylori infection

Background

Helicobacter pylori (H. pylori) causes a diversity of gastric diseases. Rapid urease tests (RUT) are well established for the point-of-care, invasive diagnosis of H. pylori infection. The study aimed to evaluate the diagnostic performance of a new liquid RUT, the preOx-HUT, within a prospective cohort of treatment-naïve patients.

Methods

The multicenter prospective clinical trial was conducted at nine Austrian centers for gastrointestinal endoscopy. Patients referred for a diagnostic upper gastrointestinal endoscopy underwent gastric biopsy sampling for routine histological evaluation, and in parallel, the preOx-HUT. Histology served as reference standard to evaluate the diagnostic performance of the preOx-HUT.

Results

From January 2015 to January 2016, a total of 183 consecutive patients (54 males and 129 females, median age 50 years) were included. Endoscopy revealed pathological findings in 149/183 cases (81%), which were mostly gastritis (59%) and gastro-esophageal reflux disease (27%). H. pylori infection was detected by histology in 41/183 (22%) cases. In relation to histology, the preOx-HUT had a sensitivity of 85%, a specificity of 94%, a positive predictive value of 80% and a negative predictive value of 96%. Performance of preOx-HUT was not affected significantly by concomitant PPI-use as present in 15% of cases (P = 0.73).

Conclusions

This was the first study evaluating the preOx-HUT in a prospective, multicenter clinical setting. We found a high diagnostic accuracy for the point-of-care, invasive diagnostic test of H. pylori infection. Hence, this test may be a valuable diagnostic adjunct to the clinical presentation of patients with suspected H. pylori infection.

Trial registration number EK 1548/2014, Name of registry: Register der Ethikkommission der Medizinischen Universität Wien, URL of registry: https://ekmeduniwien.at/core/catalog/2012/, Date of registration: 24.09.2014, Date of enrolment of the first participant to the trial: 15.01.2015

Electronic supplementary material

The online version of this article (10.1186/s13099-017-0226-5) contains supplementary material, which is available to authorized users.

Helicobacter pylori in the tonsillar tissue: a possible association with chronic tonsillitis and laryngopharyngeal reflux

Objective:

To identify Helicobacter pylori infection in tonsillar tissue samples from patients undergoing tonsillectomy for chronic tonsillitis versus tonsillar hypertrophy, and to assess the possible relationships between H pylori and patients’ sociodemographic data and laryngopharyngeal reflux.

Methods:

In this prospective study, 97 patients who underwent tonsillectomy were divided into the following 2 groups: patients with chronic tonsillitis (n = 62) and patients with tonsillar hypertrophy (control group; n = 35). H pylori infection in the tonsillar biopsy samples was identified using histochemical and rapid urease tests.

Results:

The incidence of H pylori infection was significantly higher in the chronic tonsillitis group (56.5 per cent) compared to the control group (31.4 per cent). Similar findings were obtained for both subgroups of adults (68.6 vs 42.3 per cent) and children (40.7 vs 0.0 per cent). Significant relationships between a positive H pylori finding and laryngopharyngeal reflux related signs of vocal fold oedema, diffuse laryngeal oedema and hypertrophy of the posterior commissure were revealed.

Conclusion:

H pylori infection may be related to chronic tonsillitis and laryngopharyngeal reflux.

Diagnosis of Helicobacter pylori infection: Current options and developments

Accurate diagnosis of Helicobacter pylori (H. pylori) infection is a crucial part in the effective management of many gastroduodenal diseases. Several invasive and non-invasive diagnostic tests are available for the detection of H. pylori and each test has its usefulness and limitations in different clinical situations. Although none can be considered as a single gold standard in clinical practice, several techniques have been developed to give the more reliable results. Invasive tests are performed via endoscopic biopsy specimens and these tests include histology, culture, rapid urease test as well as molecular methods. Developments of endoscopic equipment also contribute to the real-time diagnosis of H. pylori during endoscopy. Urea breathing test and stool antigen test are most widely used non-invasive tests, whereas serology is useful in screening and epidemiological studies. Molecular methods have been used in variable specimens other than gastric mucosa. More than detection of H. pylori infection, several tests are introduced into the evaluation of virulence factors and antibiotic sensitivity of H. pylori, as well as screening precancerous lesions and gastric cancer. The aim of this article is to review the current options and novel developments of diagnostic tests and their applications in different clinical conditions or for specific purposes.

Diagnostic accuracy of reused Pronto Drytest and CLOtest in the detection of Helicobacter pylori infection

Background

Unchanged substrate in a negative rapid urease test may be reused to detect Helicobacter pylori (H. pylori). This could potentially reduce costs and wastage in low prevalence and resource-poor settings. We thus aimed to investigate the diagnostic accuracy of reused Pronto Dry® and CLOtest® kits, comparing this to the use of new Pronto Dry® test kits and histopathological evaluation of gastric mucosal biopsies.

Methods

Using a cross-sectional study design, subjects who presented for upper endoscopy due to various non-emergent causes had gastric biopsies obtained at three adjacent sites. Biopsy samples were tested for H. pylori using a reused Pronto Dry® test, a reused CLOtest®, a new Pronto Dry® test and histopathological examination. Concordance rates, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy were then determined.

Results

A total of 410 subjects were recruited. The sensitivity and diagnostic accuracy of reused Pronto Dry® tests were 72.60 % (95 % CI, 61.44 – 81.51) and 94.15 % (95 % CI, 91.44 – 96.04) respectively. For reused CLOtests®, the sensitivity and diagnostic accuracy were 93.15 % (95 % CI 85.95 – 97.04) and 98.29 % (95 % CI 96.52 – 99.17) respectively. There were more true positives for new and reused Pronto Dry® pallets as compared to new and reused CLOtests® when comparing colour change within 30 min vs. 31–60 min (P < 0.001 and P = 0.7 respectively).

Conclusion

Negative Pronto Dry® and CLOtest® kits may be reused in a low prevalence setting where cost issues remain paramount. Reused CLOtest® kits have better accuracy than reused Pronto Dry® tests. Reused Pronto Dry® tests however have a more rapid colour change whilst maintaining diagnostic accuracy.

Evaluation of methods for H. pylori detection in PPI consumption using culture, rapid urease test and smear examination

BACKGROUND

Culture, rapid urease test (RUT) and smear examination have been used as reliable methods for diagnosis of H. pylori infection. Accurate performance of these tests requires good quality biopsies with considerable number of bacterial cells. However, consumption of proton pump inhibitors (PPIs) affects growth and urease activity of H. pylori, leading to false negative results. In this study the efficacy of culture, RUT and smear examination was assessed and the effect of PPI consumption was evaluated.

METHODS

Two antral biopsies from 530 dyspeptic patients with and without PPI consumption were used for RUT, culture and smear examination. Statistical analysis was used to determine the association between results of culture, RUT or smear examination and PPI consumption. Sensitivity and specificity of three tests were calculated by standard methods.

RESULTS

H. pylori infection was detected in 40% of patients by culture, 48.3% by RUT and 21.1% by smear examination and the overall detection rate was 54%. A strong correlation was found between PPI consumption and negative results of culture and RUT (P<0.05) but not smear examination. The sensitivity of RUT was reduced as a result of PPI consumption. This reduction was more profound in 1-hr RUT (92.2% to 74.4%) compared with 24-hr RUT (93.9% to 81.6%).

CONCLUSIONS

Prevalence of H. pylori was declined, compared with previous studies. This decrement could be due to false negative results of H. pylori diagnostic tests, among which culture and RUT are mostly affected by PPI. Accordingly, PPI consumption should be stopped before performance of endoscopy.

Helicobacter pylori infection - recent developments in diagnosis

Considering the recommended indications for Helicobacter pylori (H. pylori) eradication therapy and the broad spectrum of available diagnostic methods, a reliable diagnosis is mandatory both before and after eradication therapy. Only highly accurate tests should be used in clinical practice, and the sensitivity and specificity of an adequate test should exceed 90%. The choice of tests should take into account clinical circumstances, the likelihood ratio of positive and negative tests, the cost-effectiveness of the testing strategy and the availability of the tests. This review concerns some of the most recent developments in diagnostic methods of H. pylori infection, namely the contribution of novel endoscopic evaluation methodologies for the diagnosis of H. pylori infection, such as magnifying endoscopy techniques and chromoendoscopy. In addition, the diagnostic contribution of histology and the urea breath test was explored recently in specific clinical settings and patient groups. Recent studies recommend enhancing the number of biopsy fragments for the rapid urease test. Bacterial culture from the gastric biopsy is the gold standard technique, and is recommended for antibiotic susceptibility test. Serology is used for initial screening and the stool antigen test is particularly used when the urea breath test is not available, while molecular methods have gained attention mostly for detecting antibiotic resistance.

3rd Brazilian Consensus on Helicobacter pylori

Signicant progress has been obtained since the Second Brazilian Consensus Conference on Helicobacter pylori Infection held in 2004, in São Paulo, SP, Brazil, and justify a third meeting to establish updated guidelines on the current management of H. pylori infection. The Third Brazilian Consensus Conference on H pylori Infection was organized by the Brazilian Nucleus for the Study of Helicobacter, a Department of the Brazilian Federation of Gastroenterology and took place on April 12-15, 2011, in Bento Gonçalves, RS, Brazil. Thirty-one delegates coming from the five Brazilian regions and one international guest, including gastroenterologists, pathologists, epidemiologists, and pediatricians undertook the meeting. The participants were allocated in one of the five main topics of the meeting: H pylori, functional dyspepsia and diagnosis; H pylori and gastric cancer; H pylori and other associated disorders; H pylori treatment and retreatment; and, epidemiology of H pylori infection in Brazil. The results of each subgroup were submitted to a final consensus voting to all participants. Relevant data were presented, and the quality of evidence, strength of recommendation, and level of consensus were graded. Seventy per cent and more votes were considered as acceptance for the final statement. This article presents the main recommendations and conclusions to guide Brazilian doctors involved in the management of H pylori infection.

Helicobacter pylori infection in laryngeal diseases

Clinical studies have shown that Helicobacter pylori can be found not only in the mucosa of the stomach, but in the pharyngeal and laryngeal regions as well. The aim of this prospective case-control study was to identify H. pylori infection in the biopsy material from the larynx of the patients suffering from benign laryngeal diseases (vocal fold polyps, laryngitis) and laryngeal cancer and to investigate the possible relationships between the laryngeal H. pylori and patients' socio-demographic data and laryngopharyngeal reflux. The results of the biopsy material from 67 adult patients treated for benign laryngeal diseases and laryngeal cancer and 11 individuals of the control group revealed that H. pylori infection could be identified in more than one-third of the patients. In the majority of cases H. pylori was found in the patients with chronic laryngitis (45.5%) and laryngeal cancer (46.2%). The findings of these sub-groups significantly differed from those of the control group (9.1%) (p < 0.05). No significant relationships between H. pylori infection found in the laryngeal region and patients' demographic data, their unhealthy habits and reflux-related symptoms or signs were obtained. It could be concluded that H. pylori can colonize in the larynx of patients with benign laryngeal diseases and laryngeal cancer. To clarify the role of H. pylori as a risk factor for laryngeal diseases further research is needed.

Comparison of the 13C-urea breath test and the endoscopic phenol red mucosal pH test in the quantification of Helicobacter pylori infection loading

BACKGROUND/AIMS

The (13)C-urea breath test (UBT) is a semiquantitative test for measuring Helicobacter pylori infection loading. H. pylori produces ammonia, which elevates the pH of the gastric mucosa and is detectable via endoscopy using a phenol red indicator. We evaluated whether this test could be used to diagnose H. pylori infection and whether phenol red staining was correlated with (13)C-UBT results.

METHODS

One hundred and twenty-three patients participated. The UBT was performed after ingestion of a capsule containing urea. A change in (13)C-UBT >2 ppt was selected as the cutoff value for diagnosing infection. After spraying evenly with a 0.1% phenol red solution, the pH of the gastric mucosal surface was measured using an antimony electrode through the biopsy channel.

RESULTS

The pH of stained mucosa (6.9+/-0.4) was significantly higher than that of unstained mucosa (1.9+/-0.8; p<0.001), and the H. pylori detection rate confirmed via histology was higher in stained versus unstained mucosa (p<0.01). Extensive mucosal staining resulted in a higher detection rate (p<0.001). The UBT produced results were very similar to those obtained via histological detection in stained mucosa (p<0.001). The extent of staining, expressed as a staining score, was positively correlated with the change in (13)C-UBT (r=0.426, p<0.001). A significant correlation was also observed between the histologically determined H. pylori density and (13)C-UBT results (r=0.674, p<0.001).

CONCLUSIONS

H. pylori infection elevates gastric mucosal surface pH, and endoscopic phenol red staining may be an alternative method for the diagnosis of H. pylori infection.

Significantly elevated Helicobacter pylori density and different genotype distribution in erosions as compared with normal gastric biopsy specimen detected by quantitative real-time PCR

BACKGROUND AND AIM

Determination of the local densities of Helicobacter pylori and its genotypic variations in gastric biopsy specimens by using novel real-time PCR-based methods could support the precise diagnosis and understanding of H. pylori infections.

METHODS

Serial dilutions of H. pylori (0.016-16 microg/microl), control, bacterial, and human DNA samples were prepared. Fresh-frozen gastric biopsy specimens were taken from 103 patients, and the DNA was isolated. Quantitative determination of the ureaseA gene using hybridization probes with parallel evaluation of an internal human control gene (beta-globin) was performed by real-time PCR. CagA and VacA s1 genotypic characterizations were also performed. The data were compared with urea breath test (UBT), histology, and serological testing.

RESULTS

The presence of H. pylori could be detected by ureaseA-fluorescence energy transfer (53%), UBT (51%), serological testing (48%), and histology (52%) when compared with the gold standard (54%). A significant correlation was found between the quantitative real-time ureaseA/beta-globin ratio-based H. pylori frequency and the UBT results (P<0.01). Significantly increased bacterial density was found in the erosions when compared with the healthy part of the antrum and corpus (P<0.01). Real-time PCR VacA s1 results were in significant correlation (P<0.01) with those of serological tests, but CagA results were not. The genomic profiles (VAC/GAC) were different in 13.7% of the cases, which involved three different locations in the stomach.

CONCLUSION

Real-time PCR was the most reliable method for H. pylori diagnosis. Furthermore, quantification and genotyping could also be performed using this technique. The density of H. pylori was significantly increased in macroscopic erosions.

A critical evaluation of the evidence on a causal relationship betweenHelicobacter pyloriand otitis media with effusion

Objective:

There is growing interest in the presence ofHelicobacter pyloriin the upper aerodigestive tract, and in the middle ear in patients with otitis media with effusion. Some studies have reported detectingH pyloriin the middle ear, although reports to the contrary exist. In this study, we critically evaluate the evidence for the theory thatH pyloriin the middle ear plays a role in otitis media with effusion.

Material:

We undertook a systematic review of all available studies investigating the presence ofH pyloriin the middle ear of patients with otitis media with effusion. The current literature was critically analysed using the key words and phrases ‘Helicobacter pylori’ ‘otitis media with effusion’, ‘serous otitis media’, ‘glue ear’ and ‘middle ear’. Six original research papers were identified, studying a total of 203 patients and 27 controls; two of these papers were randomised, controlled studies and four were prospective, cohort studies.

Results:

At present, there is poor evidence for the existence ofH pylori-associated otitis media with effusion.

Conclusions:

Further research in the field is needed in order to delineate the presence ofH pyloriand its role in the pathogenesis of otitis media with effusion.

Diagnosis of Helicobacter pylori: invasive and non-invasive tests

Helicobacter pylori infection can be diagnosed by invasive techniques requiring endoscopy and biopsy (e.g. histological examination, culture and rapid urease test) and by non-invasive techniques, such as serology, the urea breath test, urine/blood or detection of H. pylori antigen in stool specimen. Some non-invasive tests, such as the urea breath test and the stool antigen test, detect active infection: these are called 'active tests'. Non-invasive tests (e.g. serology, urine, near-patient tests) are markers of exposure to H. pylori but do not indicate if active infection is ongoing; these are 'passive tests'. Non-invasive test-and-treat strategies are widely recommended in the primary care setting. The choice of appropriate test depends on the pre-test probability of infection, the characteristics of the test being used and its cost-effectiveness.

Diagnosis of Helicobacter pylori infection

A growing interest in non-invasive tests for the detection of Helicobacter pylori has been observed recently, reflecting a large number of studies published this year. New tests have been validated, and the old ones have been used in different clinical situations or for different purposes. Stool antigen tests have been extensively evaluated in pre- and post-treatment settings both in adults and children, and the urea breath test has been studied as a predictor of bacterial load, severity of gastric inflammation, and response to eradication treatment. Several studies have also explored the usefulness of some serologic markers as indicators of the gastric mucosa status. With regard to invasive tests, molecular methods are being used more and more, but the breakthrough this year was the direct in vivo observation of H. pylori during endoscopy.

Diagnosis of Helicobacter pylori Infection

A large number of studies on diagnostic tests have been published this year. New tests were proposed for the detection of Helicobacter pylori antigens in stools and new molecular methods (real-time polymerase chain reaction) to look for antimicrobial susceptibility. The other standard tests have been applied in different situations to improve the diagnosis of the infection.