Comparison of a monoclonal with a polyclonal antibody-based enzyme immunoassay stool test in diagnosing Helicobacter pylori infection before and after eradication therapy

Diagnosis of Helicobacter pylori Infection and Recent Advances

BACKGROUND

Helicobacter pylori (H. pylori) infects approximately 50% of the world population. Its infection is associated with gastropathies, extra-gastric digestive diseases, and diseases of other systems. There is a canonical process from acute-on-chronic inflammation, chronic atrophic gastritis (CAG), intestinal metaplasia (IM), dysplasia, and intraepithelial neoplasia, eventually to gastric cancer (GC). H. pylori eradication abolishes the inflammatory response and early treatment prevents the progression to preneoplastic lesions.

METHODS

the test-and-treat strategy, endoscopy-based strategy, and screen-and-treat strategy are recommended to prevent GC based on risk stratification, prevalence, and patients' clinical manifestations and conditions. Challenges contain false-negative results, increasing antibiotic resistance, decreasing eradication rate, and poor retesting rate. Present diagnosis methods are mainly based on invasive endoscopy and noninvasive laboratory testing.

RESULTS

to improve the accuracy and effectiveness and reduce the missed diagnosis, some advances were achieved including newer imaging techniques (such as image-enhanced endoscopy (IEE), artificial intelligence (AI) technology, and quantitative real-time polymerase chain reaction (qPCR) and digital PCR (dPCR).

CONCLUSION

in the article, we summarized the diagnosis methods of H. pylori infection and recent advances, further finding out the opportunities in challenges.

Clinical Performance of the Automated LIAISON® Meridian H. pylori SA Stool Antigen Test

Background

Antigens derived from Helicobacter pylori can be used as stool biomarkers to assist in the diagnosis of H. pylori infection. Since current assays have variable performance, we assessed the clinical performance of the automated LIAISON® Meridian H. pylori infection. Since current assays have variable performance, we assessed the clinical performance of the automated LIAISON® Meridian

Methods

This prospective multisite study enrolled patients undergoing an esophagogastroduodenoscopy with collection of biopsy and stool specimens. Adult patients (≥22 years) participated in the study from February 2017 to August 2018. Specimens of the stomach were tested by three methods, known as the Composite Reference Method: (1) histological evaluation, (2) culture of the organism, and (3) rapid urease detection test. H. pylori infection. Since current assays have variable performance, we assessed the clinical performance of the automated LIAISON® Meridian H. pylori infection. Since current assays have variable performance, we assessed the clinical performance of the automated LIAISON® Meridian

Results

277 patients (63% female) were included in the study. The prevalence of infected subjects was 24.2% in this study cohort. Clinical performance assessed against the Composite Reference Method showed very good agreement (Cohen′s kappa = 0.922), with good sensitivity (95.5%) and specificity (97.6%). Reproducibility study results showed total imprecision ranging from 3.1% to 13.9% CV.

Conclusion

The automated LIAISON® Meridian H. pylori SA assay brings reliable noninvasive testing for H. pylori to the laboratory that is in very good agreement with the current, more invasive biopsy-based methods such as histology, culture, or rapid urease test. The clinical trial identifiers are NCT03060746 (pretherapy) and NCT03060733 (posttherapy).H. pylori infection. Since current assays have variable performance, we assessed the clinical performance of the automated LIAISON® Meridian H. pylori infection. Since current assays have variable performance, we assessed the clinical performance of the automated LIAISON® Meridian

Recurrent abdominal pain and upper gastrointestinal endoscopy findings in children and adolescents presenting at the Lagos University Teaching Hospital

INTRODUCTION

Recurrent abdominal pain (RAP) is a common reason for referral to the paediatric gastroenterology unit and the attending physician needs to be able to rule out an organic cause when evaluating any child with this condition. The aim of this study was to describe the endoscopic findings in children who presented to the paediatric gastroenterology unit of the Lagos University Teaching Hospital (LUTH) with RAP.

METHODS

This was a prospective descriptive study which was conducted from January 2015 to July 2018 at the Paediatric Gastroenterology unit of the department of Paediatrics and the endoscopy unit of the LUTH, Lagos, Nigeria. All children and adolescents ≤ 19 years old with recurrent abdominal pain who were referred for upper GI endoscopy during the study period, were recruited. Baseline sociodemographic data, dyspepsia and alarm symptoms if present were documented. Results of other investigations namely stool examination for ova, parasites, occult blood and faecal antigen for Helicobacter pylori and abdominal scan were also documented.

RESULTS

A total of 113 children with recurrent abdominal pain was referred during the study period and 87 (76.7%) of them had upper GI endoscopy done. Out of the participants, 38(43.7%) were boys and 49(56.3) girls. Alarm features were present in 15(17.6%) and dyspepsia was seen in 22(25.3%) of the subjects. The main endoscopic findings were: gastritis in 39 (44.8%), gastric erosions in 14(16.2%), hiatus hernia in 7(8.1%), duodenitis in 6 (6.9%), gastric polyp in 4 (4.6%).

CONCLUSION

Upper GI endoscopy remains an invaluable tool in the tool in evaluating RAP in children as it enables accurate diagnosis of GI causes of RAP. There is a need to advocate for easier access to this procedure in the developing countries.

Non-invasive tests for the diagnosis of helicobacter pylori: state of the art

Usually, non-invasive tests are the first methods for diagnosing Helicobacter pylori (HP) infection. Among these, serological test, stool antigen research and urea breath test are the most used. Antibodies anti-HP are not recommended in low prevalence population, moreover they cannot reveal an ongoing infection, but they only prove a contact with the bacterium. Also, they can persist for a long time after the eradication of the infection, therefore, they should not be used to verify the success of eradication therapy. Stool antigen research and Urea Breath Test (UBT) are useful both in diagnosis and during follow-up after eradication treatment. The stool antigen test is cheaper than Urea breath test with similar sensitivity and specificity. Non-invasive tests are not able to diagnose the associated complications to HP infection. (www.actabiomedica.it)

Characteristics of Helicobacter pylori-seropositive subjects according to the stool antigen test findings: a prospective study

BACKGROUND/AIMS

In countries with a higher risk of gastric atrophic gastritis, noninvasive tests are helpful for a more reliable diagnosis of Helicobacter pylori infection. The aim of this study was to evaluate the characteristics of seropositive subjects according to their stool H. pylori antigen test, serum pepsinogen (PG) assay, and endoscopic findings.

METHODS

Consecutive subjects who visited Konkuk University Medical Center for upper gastrointestinal endoscopy for a regular check-up were included in a prospective setting if the serum anti-H. pylori immunoglobulin G assay was positive. A H. pylori antigen stool test was measured using a stool H. pylori antigen enzyme-linked immunosorbent assay kit on the same day as a serum PG assay and endoscopy.

RESULTS

Of 318 seropositive subjects, 256 (80.5%) showed positive stool test findings. Subjects with a negative stool test result showed lower serum PG I (p < 0.001) and PG II (p < 0.001) levels and higher PG I/II ratio (p < 0.001) than those with a positive stool test. Chronic atrophic gastritis was more common in the positive stool test group than the negative stool test group on endoscopic finding (p = 0.009). A higher serum PG I level (p = 0.001) and a lower serum PG I/II ratio (p = 0.001) were independent risk factors for the presence of H. pylori antigen in stool.

CONCLUSION

A high serum PG level denotes an ongoing current H. pylori infection with positive stool H. pylori antigen test findings. Seropositive subjects with increased gastric secreting ability tend to have H. pylori in their fecal material as reflected by a positive stool H. pylori antigen test finding.

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.

Stool antigen detection versus 13C-urea breath test for non-invasive diagnosis of pediatric Helicobacter pylori infection in a limited resource setting

INTRODUCTION

The prevalence of childhood infection with Helicobacter pylori is high, especially in developing countries. Non-invasive methods for detection of infection in children should be inexpensive, easy to perform, well tolerated and have a high diagnostic accuracy. We aimed to compare the reliability, specificity and sensitivity of the H. pylori stool antigen (HpSA) test with the ¹³C-urea breath test (¹³C-UBT) for the diagnosis of H. pylori infection in a limited resource setting.

MATERIAL AND METHODS

The stool samples of 60 symptomatic and dyspeptic children with a mean age of 7.2 ±3.7 years (2-15 years) were evaluated using the rapid One step HpSA test by lateral flow immunoassay. The ¹³C-UBT was used as the gold standard method for the diagnosis of H. pylori infection.

RESULTS

The HpSA test detected H. pylori antigen in 34 out of 38 positive patients with 4 false-negatives (sensitivity 89.5%, 95% confidence interval (CI): 75.2-97.1%), while 21 patients had true-negative results and one false-positive (specificity 95.5%, 95% CI: 77.2-99.9%), with a strong measure of agreement between the HpSA test and the ¹³C-UBT (κ = 0.83, 95% CI: 68-97%, p < 0.001). It had a positive predictive value of 97.1% (95% CI: 85.1-99.9%), a negative predictive value of 84% (95% CI: 63.9-95.5%) and an accuracy of 91.7%.

CONCLUSIONS

The rapid lateral flow HpSA test is a reliable method for the primary diagnosis of H. pylori infections in children, though not as accurate as the ¹³C-UBT. It is more affordable, simpler to perform and more tolerable, representing a viable alternative, especially in developing countries.

Review article: the global emergence of Helicobacter pylori antibiotic resistance

BACKGROUND

Helicobacter pylori is one of the most prevalent global pathogens and can lead to gastrointestinal disease including peptic ulcers, gastric marginal zone lymphoma and gastric carcinoma.

AIM

To review recent trends in H. pylori antibiotic resistance rates, and to discuss diagnostics and treatment paradigms.

METHODS

A PubMed literature search using the following keywords: Helicobacter pylori, antibiotic resistance, clarithromycin, levofloxacin, metronidazole, prevalence, susceptibility testing.

RESULTS

The prevalence of bacterial antibiotic resistance is regionally variable and appears to be markedly increasing with time in many countries. Concordantly, the antimicrobial eradication rate of H. pylori has been declining globally. In particular, clarithromycin resistance has been rapidly increasing in many countries over the past decade, with rates as high as approximately 30% in Japan and Italy, 50% in China and 40% in Turkey; whereas resistance rates are much lower in Sweden and Taiwan, at approximately 15%; there are limited data in the USA. Other antibiotics show similar trends, although less pronounced.

CONCLUSIONS

Since the choice of empiric therapies should be predicated on accurate information regarding antibiotic resistance rates, there is a critical need for determination of current rates at a local scale, and perhaps in individual patients. Such information would not only guide selection of appropriate empiric antibiotic therapy but also inform the development of better methods to identify H. pylori antibiotic resistance at diagnosis. Patient-specific tailoring of effective antibiotic treatment strategies may lead to reduced treatment failures and less antibiotic resistance.

Development of an immunochromatographic lateral flow device for rapid detection of Helicobacter pylori stool antigen

OBJECTIVE

Helicobacter pylori stool antigen (HpSA) test is a convenient and reliable non-invasive diagnosis for H. pylori infection. The aim of this study is to develop an immunochromatographic testing device for rapid detection of HpSA among Chinese patients.

DESIGN AND METHODS

Monoclonal antibodies (McAb) targeting H. pylori were developed by conventional methods and paired by sandwich ELISA. The lateral flow device (LFD) was prepared using the selected McAb pair. A total of 867 clinically separated bacterial strains, including 56H. pylori strains, were employed to test the sensitivity and specificity. Subsequently, the LFD was used to test 1200 human fecal samples, with a commercial HpSA testing device as comparison.

RESULTS

Two McAb pairs targeting H. pylori, DF2a/EE10b and IH10b/EE10b, were developed and proven to be of high specificity and sensitivity. After testing the cultures of 56 clinically separated H. pylori strains, the final LFD product was prepared using the mixture of DF2a and IH10b as capture antibodies and EE10b as the detection antibody. The testing threshold for H. pylori culture was 1.0 × 10(4)cfu/mL. The sensitivity and specificity were both 100% for the 867 tested bacterial cultures. The testing results of 1200 fecal samples showed that the positive and negative agreement rates between the homemade LFD and the commercial testing device were 99.75% and 99.87%, respectively.

CONCLUSION

Our homemade HpSA LFD can be a very promising testing device for rapid diagnosis and epidemic screening of H. pylori infection among Chinese patients.

Evaluation of an Iranian Home-made Helicobacter pylori Stool Antigen ELISA Kit

Background:

Current diagnosis of Helicobacter pylori infection by biopsy-based tests requires invasive sampling. Non-invasive methods such as the H. pylori stool-antigen (HpSA) test may be the best alternative for diagnosis of active infection. However, due to the presence of antigenic-diversity among the strains, various commercial tests have shown some discrepancies in different geographical-areas.

Objectives:

This study evaluates a homemade HpSA kit developed by using the H. pylori antigens from Iranian-isolates for detection of H. pylori in the stool of infected patients.

Patients and Methods:

Based on the endoscopic features and/or a rapid-urease test (RUT), 30 child and 50 adult patients, were recruited. From these candidates, three biopsies for RUT, culture and histology, and a stool-sample, were obtained. Patients were considered as H. pylori-positive if culture alone or RUT plus histology were found to be positive. Presence of H. pylori antigens in their stools was detected by the homemade HpSA test and an imported HpSA kit (Immundiagnostik, Germany).

Results:

Using the biopsy-based tests with RUT, histology and culture, 53% (16/30) of children were diagnosed as H. pylori–positive while using the imported kit 57% and the homemade kit 50% of the candidates showed positive results. Also by the biopsy-based tests, 54% of the adults were diagnosed as H. pylori-positive while by the homemade kit 56% showed positive results. Considering the biopsy-based tests as the gold standard, sensitivity and specificity for the imported kit was 94% and 86%, respectively, while the mean sensitivity and specificity for the homemade kit was 96% and 98%, respectively.

Conclusions:

The homemade kit, compared with the imported kit and biopsy-proven tests may be a valid and reliable method for determining the presence of H. pylori infection in Iran.

Stool antigen tests for the management of Helicobacter pylori infection

Stool antigen tests (SATs) are noninvasive diagnostic modules for Helicobacter pylori (H. pylori) infection. Two types of SATs exist for the diagnosis of H. pylori infection, one based on enzyme immunoassay (EIA) and another on immunochromatography (ICA). SATs do not require expensive chemical agents or specified equipment; hence, they are less expensive compared with the urea breath test. Both European and Japanese guidelines have shown that EIA-based SATs using monoclonal antibodies are useful for primary diagnosis as well as for the assessment of eradication therapy. ICA-based tests do not require particular equipment and are therefore useful in developing countries. SATs are also useful for the diagnosis of H. pylori infection in children and post gastric surgery patients. SATs performed via EIA can assess H. pylori infection in a large number of subjects, almost as well as serology. Thus, SATs would be useful or detecting current infection in such a survey to identify and eradicate H. pylori infection. The accuracy of SATs is lower when the stool samples are unformed or watery, because H. pylori-specific antigens in the stool samples are diluted. Temperature and the interval between stool sample collection and measurement also affect the results of SATs. The choice of test kit depends on the sensitivity and specificity in each region and the circumstances of each patient.

Applicability of a rapid stool antigen test, using monoclonal antibody to catalase, for the management of Helicobacter pylori infection

BACKGROUND

Most monoclonal antibody-based stool antigen tests are of the "send-out" format. Rapid Testmate pylori antigen (Rapid TPAg) uses monoclonal antibody and is an "in-the-office" test. The aim of this study was to examine the usefulness of Rapid TPAg for the management of H. pylori infection.

METHODS

One-hundred and two consecutive patients who received H. pylori eradication therapy underwent both urea breath test (UBT) and Rapid TPAg at 5-6 weeks after finishing the eradication therapy. Stool samples were maintained at -20, 5, 25, and 40°C and subjected to Rapid TPAg after 1-7 days. Stool samples were also tested by enzyme immunoassay (EIA) to quantify antigenicity.

RESULTS

The agreement between Rapid TPAg and UBT in the evaluation of the results of H. pylori eradication treatment was 94.1%. The overall accuracy of Rapid TPAg and UBT to determine H. pylori eradication was 98.0 and 96.0%, respectively. The results of Rapid TPAg were not altered after storage of samples at -20 to 40°C for 7 days. Antigenicity quantified by EIA did not decrease significantly after 7 days.

CONCLUSIONS

Rapid TPAg is a useful diagnostic test for immediate and accurate determination of the results of H. pylori eradication therapy. The antigenicity of stool sample suspensions was preserved for 7 days in the collection devices.

Accuracy of monoclonal stool tests for determining cure of Helicobacter pylori infection after treatment

BACKGROUND

Studies comparing new monoclonal fecal tests for evaluating cure of Helicobacter pylori infection after treatment are scarce. The objective was to compare the diagnostic accuracy of three monoclonal stool tests: two rapid in-office tools -RAPID Hp StAR and ImmunoCard STAT! HpSA - and an EIA test - Amplified IDEIA Hp StAR.

MATERIALS AND METHODS

Diagnostic reliability of the three tests was evaluated in 88 patients at least 8 weeks after H. pylori treatment. Readings of immunochromatographic tests were performed by two different observers. Sensitivity, specificity, positive and negative predictive values and 95% confidence intervals were calculated.

RESULTS

All tests presented similar performance for post-eradication testing. Sensitivity for detecting persistent infection was 100% for both Amplified IDEIA and RAPID Hp StAR and 90% for ImmunoCard STAT! HpSA. Respective specificities were 94.9%, 92.3-93.6% and 94.9%. Negative predictive values were very high (100%, 100% and 98.7% respectively). But positive predictive values were lower, ranging from 62.5 to 71.4%.

CONCLUSION

All monoclonal fecal tests in this series presented similar performance in the post-treatment setting. A negative test after treatment adequately predicted cure of the infection. However, nearly a third of tests were false positive, showing a poor predictive yield for persistent infection.

Comparison of a stool antigen test and serology for the diagnosis of Helicobacter pylori infection in mass survey

BACKGROUND

Serum antibody to Helicobacter pylori is tested in mass screening for gastric cancer along with the level of serum pepsinogens (PG) I and II. Recently, stool antigen tests have been developed as a new non-invasive test. We examined H. pylori infection by both serology and stool antigen test in a mass survey and compared the results to estimate applicability of stool antigen test for mass survey.

METHODS

A total of 994 healthy adults who received mass survey in April 2005 were tested. There were 379 men and 615 women, and the mean age was 57.7 years old. Stool samples were used to measure a H. pylori-specific antigen by enzyme immunoassay. Serum samples were tested for the prevalence of IgG antibody to H. pylori, and the level of PGs I and II was also measured to determine the presence of atrophic gastritis.

RESULTS

Infection of H. pylori was defined as positive 61.4% and 56.4% by serology and stool antigen test, respectively. The concordance of both tests was not affected by gender and age of the subjects but difference was seen in subjects with atrophic gastritis. In particular, positivity of stool antigen test (81.8%) was significantly lower than that of serology (88.7%, p < .05) in 303 subjects with severe atrophic gastritis.

CONCLUSIONS

Stool antigen test, which detects present but not previous infection of H. pylori, would be applicable to diagnose H. pylori infection in mass survey. Usefulness of stool antigen tests for the screening of gastric cancer should be examined.

Evaluation of a latex agglutination test (PYLOGEN) for the detection of Helicobacter pylori in stool specimens

The aim of the study was to assess a new latex agglutination (LA) stool antigen assay (PYLOGEN; CerTest Biotec, Zaragoza, Spain) in the diagnosis of Helicobacter pylori infection and to monitor its eradication after treatment. The LA test has been approved for sale in Europe, and its approval from the US Food and Drug Administration is still pending. The individuals enrolled were classified into 3 groups of patients: Group 1 consisted of 38 patients who are H. pylori positive. The diagnosis of H. pylori infection was established if there was concordance between 2 test results (urea breath test [UBT], rapid urease test, and histopathologic study) or if the culture alone was positive. Patients with only 1 positive test were considered indeterminate and were excluded from the study. Group 2 comprised 9 patients without positive tests and who were considered to be H. pylori negative. Group 3 consisted of 57 patients who received eradication treatment. The sensitivity and specificity of the test were 78.9% and 100%, respectively. The results of the UBT of the patients were studied 6 weeks after eradication therapy. The sensitivity and specificity of the LA test relative to UBT for patients after treatment were 75% and 93.3%, respectively.

Evaluation of the monoclonal stool antigen test for Helicobacter pylori in an Asian population with dyspepsia

OBJECTIVE

Although well established in the West, stool antigen tests (SAT) are not widely used in Asia. Data on the accuracy of this test in Asia is sparse and, to date, there have been no studies looking at the more refined monoclonal SAT. The aim of this study is to validate the diagnostic accuracy of a stool antigen test, Hp STAR, for the detection of Helicobacter pylori.

METHODS

Consecutive new patients with dyspepsia, referred to the endoscopy unit were recruited. At endoscopy, biopsies were taken for rapid urease tests and histology. Stool specimens were collected before any therapy was given and were tested for H. pylori using the monoclonal SAT HpSTAR test. Samples were collected from 90 patients. The stool antigen results were compared with the results of rapid urease tests and histopathology, which were used together as the gold standard test in the diagnosis of H. pylori.

RESULTS

Of the 90 patients tested, 45 were H. pylori positive and 45 were H. pylori negative. There was one false positive and one false negative test. The sensitivity, specificity, positive predictive value and negative predictive value for the Hp STAR were identical: 97.8% with a 95% confidence interval of 88.2-99.9%. The diagnostic accuracy was 97.8% with a 95% confidence interval of 92.2-99.7%.

CONCLUSION

The monoclonal stool antigen test, HpSTAR is a highly accurate test for the diagnosis of H. pylori.

Helicobacter pylori stool antigen assay in hyperemesis gravidarum: a risk factor for hyperemesis gravidarum or not?

OBJECTIVE

To test the hypothesis that Helicobacter pylori (H. pylori) infection may cause hyperemesis gravidarum (HG).

MATERIALS AND METHODS

A prospective-comparative study was performed on 107 pregnant patients from October 2002 to December 2003 in a university-based prenatal care clinic. Blood and stool samples were obtained from 52 patients diagnosed as HG and 55 matched asymptomatic pregnant women. H. pylori stool antigen (HpSA) status of the participants was evaluated using a commercially available enzyme immunoassay-based kit.

RESULTS

The overall prevalence of HpSA positivity appeared as 41.1%. Twenty-two of 52 (42.3%) HG patients and 22 of 55 (40.0%) control subjects were positive for HpSA. The difference was not significant (p>.05).

CONCLUSION

HG seemed to be not associated with H. pylori infection, as indicated by specific stool antigen assay.

Diagnosis of Helicobacter pylori

Although there are attempts to perform Helicobacter pylori diagnosis directly in vivo using magnification endoscopy, most articles on diagnosis this year concerned non-invasive tests and molecular methods. For urea breath tests, there are attempts to have a quicker and cheaper test and to evaluate its role in cases of premalignant lesions. For stool antigens tests, evaluation of kits using monoclonal antibodies was carried out. Molecular tests have been applied for typing and detection of resistant mutants.

Diagnostic accuracy of a rapid fecal test to confirm H pylori eradication after therapy: Prospective comparison with a laboratory stool test

AIM: To investigate the clinical performances of rapid stool test (ImmunoCard STAT HpSA, Meridian Diagnostic Inc.) in the evaluation of eradication therapy of H pylori and to compare it with a well-known and validated laboratory stool test (Amplified IDEA Hp StAR, Dako).

METHODS: Stool samples of 122 patients were evaluated after eradication therapy of H pylori. H pylori status was assessed by 13C-urea breath test (UBT). Stool specimens were tested using either the rapid immunoassay kit or the laboratory immunoassay kit.

RESULTS: Forty-three patients were infected and 79 non-infected. Sensitivity and specificity of ImmunoCard STAT and Hp StAR were 58.14% and 76.4%, and 97.47% and 98.73%, respectively (P > 0.05). Overall agreement between the two tests was 92.6% (113 of 122 cases).

CONCLUSION: ImmunoCard STAT seems to have rather low performances, and it cannot be regarded as a reliable tool in the post-treatment setting. Also Hp StAR cannot be recommended to confirm H pylori eradication after treatment.

The transmission of Helicobacter pylori: the effects of analysis method and study population on inference

Although much is known about the virulence of Helicobacter pylori, the transmission pathways for this bacterium are still unresolved. Transmission has been addressed through: (1) prevalence within families; (2) detection in fecal/oral environments; (3) detection in the abiotic/biotic environment; and (4) direct inference from strain similarity. Here, we review the molecular and biochemical methods used and discuss the relative merits of each. Furthermore, as there are differences between developing and developed nations, we discuss the results obtained from transmission studies in light of the study population. We conclude that H. pylori is probably transmitted person-to-person, facilitated by fecal-oral transmission during episodes of diarrhea or gastro-oral contact during periods of vomiting. The persistence of H. pylori in abiotic and biotic environments remains unproven but possible reactivation from viable, non-culturable coccoid forms should be further investigated. Finally, we speculate on the effect of host-pathogen interactions in confounding the inference of transmission.