Evaluation of a new enzyme immunoassay for detecting Helicobacter pylori in feces: a prospective pilot study

A Review of Helicobacter pylori Diagnostics in Africa : From the Bedside to the Laboratory

Helicobacter pylori (H. pylori) is endemic in Africa with a prevalence estimate of 79.1%. In addition, there is a significant community burden of dyspepsia in Africa, similar to other western countries. However, the majority of infected persons do not manifest the disease. In Africa, for instance, peptic ulcer disease is prevalent, whereas gastric cancer has reportedly low incidence. Therefore, it is important that testing is focused, targeting individuals most likely to benefit from treatment. In Africa, there are currently no guidelines for H. pylori testing and treatment. Empirical treatment is common due to variable access to diagnostics and health care. To assess the spectrum of H. pylori testing in Africa, we performed a literature search in PubMed over the past 10 years, 2013 to 2023. Histology was the most widely used modality in 16 out of 18 countries. Capacity for culture was shown in 11 studies, importantly across regions of Africa. H. pylori serology was demonstrated in 8 countries, although it has limited sensitivity in identifying active infection. H. pylori test-and-treat strategy has been shown to be cost-effective. Particularly in a region with high antibiotic resistance, adopting this strategy ensures that only confirmed positive patients are treated. Furthermore, test-of-cure ought to be mandatory to guide future therapies. Health authorities can leverage polymerase chain reaction facilities, left behind by the coronavirus disease 2019 pandemic, to make molecular susceptibility testing available in the near future. A systematic approach to testing incorporating indication for endoscopy and medication use is recommended.

Traditional and Modern Diagnostic Approaches in Diagnosing Pediatric Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is the most common bacterial infection worldwide, is usually acquired during childhood and is related to gastric carcinogenesis during adulthood. Therefore, its early proper diagnosis and subsequent successful eradication represent the cornerstones of gastric cancer prevention. The aim of this narrative review was to assess traditional and modern diagnostic methods in terms of H. pylori diagnosis. Several invasive and non-invasive methods were described, each with its pros and cons. The invasive diagnostic methods comprise endoscopy with biopsy, rapid urease tests, histopathological exams, cultures and biopsy-based molecular tests. Among these, probably the most available, accurate and cost-effective test remains histology, albeit molecular tests definitely remain the most accurate despite their high costs. The non-invasive tests consist of urea breath tests, serology, stool antigens and non-invasive molecular tests. Urea breath tests and stool antigens are the most useful in clinical practice both for the diagnosis of H. pylori infection and for monitoring the eradication of this infection after therapy. The challenges related to accurate diagnosis lead to a choice that must be based on H. pylori virulence, environmental factors and host peculiarities.

Current Helicobacter pylori Diagnostics

The high prevalence of Helicobacter pylori and the variety of gastroduodenal diseases caused by this pathogen necessitate the use of only accurate methods both for the primary diagnosis and for monitoring the eradication effectiveness. There is a broad spectrum of diagnostic methods available for detecting H. pylori. All methods can be classified as invasive or non-invasive. The need for upper endoscopy, different clinical circumstances, sensitivity and specificity, and accessibility defines the method chosen. This article reviews the advantages and disadvantages of the current options and novel developments in diagnostic tests for H. pylori detection. The progress in endoscopic modalities has made it possible not only to diagnose precancerous lesions and early gastric cancer but also to predict H. pylori infection in real time. The contribution of novel endoscopic evaluation technologies in the diagnosis of H. pylori such as visual endoscopy using blue laser imaging (BLI), linked color imaging (LCI), and magnifying endoscopy is discussed. Recent studies have demonstrated the capability of artificial intelligence to predict H. pylori status based on endoscopic images. Non-invasive diagnostic tests such as the urea breathing test and stool antigen test are recommended for primary diagnosis of H. pylori infection. Serology can be used for initial screening and epidemiological studies. The histology showed its value in detecting H. pylori and provided more information about the degree of gastric mucosa inflammation and precancerous lesions. Molecular methods are mainly used in detecting antibiotic resistance of H. pylori. Cultures from gastric biopsies are the gold standard and recommended for antibiotic susceptibility tests.

Treatment Approach of Refractory Helicobacter pylori Infection: A Comprehensive Review

H. pylori is the most common infection in the world and is associated with gastrointestinal and extra-gastrointestinal manifestations, including peptic ulcer disease, gastrointestinal bleeding, and lymphoproliferative disorders. Despite being discovered less than half a century ago, antibiotic resistance, exacerbated by medication non-adherence and inefficacy of proton pump inhibitors, has grown substantially, explaining the rising incidence of refractory H. pylori infection. In this review, we discuss risk factors, treatment options, surveillance and follow-up, as well as emerging therapies for refractory H. pylori.

Helicobacter Pylori: a comprehensive review for primary care providers

Helicobacter pylori is the most prevalent bacteria infecting humans resulting in a variety of gastrointestinal and extra gastrointestinal complications. Although most of the infected adults are asymptomatic, the prevalence varies in different parts of the world it is higher in Eastern and Southern Europe. Eradication of Helicobacter pylori is necessary to prevent precancerous conditions like gastric atrophy, gastric intestinal metaplasia and gastric dysplasia. This comprehensive review addresses briefly on: whom and how to test and treat including recommended first line therapies, salvage therapies, testing for eradication and strategy to be used in primary care clinics.

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.

The occurrence of Helicobacter pylori antigens in dental plaque; an association with oral health status and oral hygiene practices

PURPOSE

Helicobacter pylori present in the oral cavity can be a source of gastric infection. Since in the oral cavity H. pylori is mostly found in dental plaque, the aim of the study was to determine whether the oral health status and oral hygiene practices affect the incidence of H. pylori antigens in dental plaque.

MATERIALS AND METHODS

The study was performed in 155 patients aged 19-78 years. Patients who had taken antibiotics within 4 weeks preceding the study and those with a past history of H. pylori eradication were excluded. Each patient filled out a questionnaire on the procedures of dental plaque removal from natural teeth and dentures, and underwent oral examination. H. pylori antigens in supragingival plaque were determined by the immunological method with the use of a kit for detection of H. pylori antigens in stool samples.

RESULTS

The presence of H. pylori antigens in dental plaque was found in 65.6% of the study subjects. The oral health status, frequency of dentist visits as well as the number and technique of dental plaque removal from natural teeth and dentures did not differ significantly between patients with infected and non-infected dental plaque.

CONCLUSIONS

The occurrence of H. pylori antigens in dental plaque of natural teeth is not associated with oral health status or dental plaque removal practices from both natural teeth and removable dentures.

Application of immunoassay for detection of Helicobacter pylori antigens in the dental plaque

PURPOSE

The aim of this study was to determine the viability of the commercial test currently used for detection of H. pylori antigens in the stool for detection of H. pylori antigens in dental plaque.

MATERIALS AND METHODS

A total of 164 dyspeptic patients entered the study; 95 H. pylori infected (positive result of at least 4 of 5 diagnostic tests: Campylobacter-like organisms test (CLO test), histology, culture, stool antigens, serology) and 69 noninfected (negative results of 4 diagnostic tests: CLO test, histology, culture, stool antigens). Dental plaque was collected from natural teeth of the patients and incubated in microaerophilic conditions for 72 hours before immunoassay.

RESULTS

Experimental findings included that optimal dental plaque weight to perform the examination was over 2 mg and that preliminary incubation increased significantly the number of positive results (p<0.002). It was also found that H. pylori antigens in the dental plaque were positive in 81.2% of infected and only 17.7% of non-infected subjects (p<0.001), while the reproducibility of results was 95%.

CONCLUSIONS

The immunoassay for detection of H. pylori antigens in the stool may be used, after minor adaptations (specifically pre-incubation in microaerophilic conditions) for H. pylori antigen detection in dental plaque.

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

BACKGROUND

Recently, a novel Helicobacter pylori stool antigen test (Testmate pylori antigen EIA) using monoclonal antibodies against H. pylori catalase has been developed commercially. This study assessed the diagnostic usefulness of the stool antigen test compared with a polyclonal enzyme immunoassay (HpSA test) after H. pylori eradication.

METHODS

A total of 150 patients with H. pylori infection were treated by triple therapy with PPI and amoxicillin with either clarithromycin or metronidazole. H. pylori stool antigen was tested 4 and 8 weeks after eradication. The outcome of H. pylori eradication was assessed by urea breath test (UBT) 8 weeks after the end of therapy. Discordant results were followed by endoscopic examination.

RESULTS

Of 150 patients enrolled, H. pylori status was negative in 122 cases and positive in 28 cases, assessed by the 13C-UBT. On the other hand, the monoclonal stool antigen test results were negative in 126 cases and positive in 24. The polyclonal stool test results were negative in 126 cases and positive in 22. The overall sensitivity and specificity of the monoclonal stool antigen test were 91.6% (95% CI 85.9-97.3%) and 98.4% (95% CI 97.3-99.5%). The overall sensitivity and specificity of the polyclonal stool antigen test were 87.0% (95% CI 86.9-94.0%) and 97.5% (95% CI 96.1-98.9%).

CONCLUSION

The new stool antigen test using monoclonal antibody is useful for the diagnosis of H. pylori eradication 4 weeks after the end of treatment.

Progress in detection of gastric Helicobacter pylori infection

Precise tests or methods are the key points to improve diagnosis of Helicobacter pylori (H pylori) infection and to evaluate clinical therapeutic effect. According to the sampling location, these methods can be classified as: 1) those sampling from stomach, including morphological examination, bacterial culture, urease-dependent assays; and 2) other approaches, including serum test, gene analysis, H pylori stool antigen (H pylori-SA) detection, urine or saliva H pylori antibody detection, etc. This article reviews these methods systematically.

Helicobacter pylori infection in children: management and pharmacotherapy

Helicobacter pylori infection is mainly acquired during childhood: it is recognised as a cause of gastritis and peptic ulcer and it has been classified as a group A carcinogen by the World Health Organisation. The exact mode of transmission is as yet unknown. The aim of this review was to analyse the literature about H. pylori infection in paediatric patients. The large diffusion of H. pylori infection in paediatric patients, the absence of a specific clinical feature, the new non-invasive methods for diagnosis and follow-up, which are still not validated and the different therapeutic schedules have led to the necessity of determining the real clinical outcome in affected children and adolescents. The scope of the review was to identify better eradication therapy and the most important factors in treatment failure. The international literature has shown the importance of culture, antibiograms, the compliance of families and patients and the use of probiotics during triple eradication therapy. The review paid attention to the management, diagnostic techniques and therapy of this infection in paediatric patients.

Spontaneous elimination of Helicobacter pylori infection in a cohort of asymptomatic school children by enzyme-linked immunosorbent assay polyclonal antigen in stool

GOAL

To determine the natural evolution of the Helicobacter pylori infection through the fecal antigen of the H. pylori test in a cohort of school children during 2 consecutive years.

BACKGROUND

Studies have suggested that the spontaneous elimination rate is higher in developing countries, possibly owing to higher incidence rate.

STUDY

One hundred twelve children attending a day care center for the sons and daughters of university employees were evaluated yearly in a 2-year period using the H. pylori stool antigen test. Parents answered a questionnaire with demographic data at baseline. The test was performed according to previously standardized procedures, and results lesser than 0.140 were regarded as negative; higher than 0.016 were regarded as positive.

RESULTS

Age ranged from 0.7 to 7.48 years (3.67+/-1.98 y) at baseline, with 58% female and 42% male. H. pylori prevalence was 12.5% (14/112). There was a trend to associate low income (P=0.06), ethnicity non-white (P=0.075), and smaller house (P=0.079) to H. pylori infection at baseline in univariate analysis. Nevertheless, age was the only variable associated to prevalence at multivariate analysis. There was no significant association between H. pylori infection and intestinal parasites. There was only one new infection during the study period (incidence rate 0.53%), and 4 children cleared the infection (elimination rate 2.15%). All those children were older than 4 years.

CONCLUSIONS

Spontaneous eradication of the infection was more frequent than incidence of infection in this cohort.

Quantitative Correlation of Helicobacter pylori Stool Antigen (HpSA) Test with the Severity of H. pylori-Related Gastritis

The Helicobacter pylori (H. pylori) load in both stomach and stool and the resulting severity of gastritis are important criteria in validating the status of H. pylori infection. We aimed to assess the reliability of the H. pylori stool antigen (HpSA) test for the primary diagnosis of H. pylori infection by calculating the best cut-off value to obtain the highest sensitivity and specificity in dyspeptic patients. We also investigated the correlation of HpSA test with the severity of gastritis and H. pylori load. The H. pylori statuses of 95 patients were evaluated by the positivity of both rapid urease test and microscopic detection of H. pylori in biopsy specimens, 88 subjects of whom were H. pylori positive. The sensitivity and specificity of the HpSA test were 51.1% (45/88) and 100% (7/7), respectively, according to the manufacturer's recommended cut-off value of 0.16. However, with the best cut-off value of 0.048, calculated by receiver operator characteristics analysis, the sensitivity of the test increased to 92.0% (81/88) with the same specificity. High values of the HpSA test were correlated with high scores of corpus H. pylori load and the severity of antrum and corpus inflammation (p < 0.05). With the best cut-off value of the HpSA test, the primary diagnosis of H. pylori infection can be made with higher sensitivity and specificity. The HpSA test is a helpful tool that evaluates the severity of H. pylori infection and the degree of gastric inflammatory activity and gastric H. pylori load.

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

BACKGROUND

Detection of Helicobacter pylori antigen in stool samples has been a subject of controversy. However, it has been included in several clinical guidelines as a recommended non-invasive testing procedure in dyspeptic patients.

AIM

To compare a monoclonal enzyme immunoassay for detection of H. pylori stool antigen (Amplified IDEIA HpStAR, DakoCytomation) with a polyclonal enzyme immunoassay (HpSA test, Premier Platinum HpSA, Meridian Diagnostics) in diagnosing infection and in determining H. pylori status after eradication treatment.

METHODS

We evaluated stool samples of 198 patients diagnosed with H. pylori infection and of 41 patients without infection. The results of the monoclonal enzyme immunoassay HpStAR were compared with those of the polyclonal enzyme immunoassay HpSA.

RESULTS

The sensitivity and specificity of HpStAR were 91.9% and 70.7%, while those of HpSA were 89.4% and 80.5%, respectively. In the 126 patients evaluated 6 weeks after eradication therapy, the overall agreement between urea breath test and HpStAR was 90.5% (P = 0.710) and between urea breath test and HpSA was 76.9% (P = 0.410).

CONCLUSIONS

HpStAR is a rapid and easy-to-perform test with similar sensitivity to HpSA in the diagnosis of H. pylori infection, although it had lower specificity. In contrast, HpStAR is more accurate after eradication therapy than HpSA.

Faecal antigen tests in the confirmation of the effect of Helicobacter eradication therapy

BACKGROUND

The frequent occurrence of Helicobacter pylori infection requires significant health care resources after eradication therapy. Therefore the non-invasive testing methods are required to alleviate the increased work-load of health care personnel and to allow an easy control of eradication therapy. Conventionally, the effect of eradication therapy has been confirmed with 13C-urea breath test 4-6 weeks after a completed eradication.

AIM

To assess the applicability of Helicobacter pylori stool antigen tests as alternatives to the breath test in the control of the effect of eradication therapy.

METHODS

Fifty patients were diagnosed Helicobacter-positive by endoscopy and histology as well as by rapid urease test from mucosal specimen. Four weeks after an eradication therapy the patients were subjected to 13C-urea breath test as well as to faecal Helicobacter pylori antigen tests with mono- and polyclonal primary antibodies.

RESULTS

The monoclonal and polyclonal stool tests had 94% and 88% sensitivity, and 100% and 97% specificity, respectively, in the detection of Helicobacter pylori infection as compared to the 13C-urea breath test. The non-invasive test results were completely parallel in patients with various grades of mucosal atrophy or intestinal metaplasia.

CONCLUSIONS

Monoclonal faecal Helicobacter pylori antigen test is slightly superior to the polyclonal test regarding the sensitivity in the detection of stool Helicobacter antigens. Due to their sufficient sensitivity and specificity, and to their practicability and cost-effectiveness, they can be recommended for non-invasive testing of Helicobacter pylori infection as alternatives to the 13C-urea breath test.

Evaluation of the Ez-HBT Helicobacter blood test to establish Helicobacter pylori eradication

BACKGROUND

The urea blood test (Ez-HBT) has been shown to compare favourably with the urea breath test in the diagnosis of active Helicobacter pylori infection.

AIM

To examine the performance characteristics of the Ez-HBT Helicobacter blood test in establishing success or failure of therapy in H. pylori-infected adults using the 13C urea breath test as the reference method.

METHODS

13C urea breath test and Ez-HBT Helicobacter blood test were performed 4-6 weeks after completion of treatment in H. pylori positive subjects. Basal urea breath samples were collected; basal Ez-HBT Helicobacter blood test samples were not. Ez-HBT Helicobacter blood test results were reported as positive, negative, or indeterminate.

RESULTS

Seventy patients generated 126 measurable sets of urea breath and blood tests. The H. pylori cure rate was 93%. The sensitivity, specificity, and accuracy of the Ez-HBT Helicobacter blood test were 100%, 97%, and 97%, respectively. Six of eight false positive and indeterminate Ez-HBT Helicobacter blood test results could be attributed to incomplete fasting or a 13C enriched diet. After correcting for the non-fasting state, the positive predictive value of the Ez-HBT Helicobacter blood test improved from 56% to 86%.

CONCLUSION

The performance characteristics of the Ez-HBT Helicobacter blood test are comparable with that of 13C-urea breath test in establishing H. pylori eradication after therapy. Errors related to incomplete fasting can be mitigated by collection of a basal blood sample.

Comparison of a monoclonal antigen stool test (Hp StAR) with the 13C-urea breath test (UBT) in monitoring Helicobacter pylori eradication therapy

AIM: To evaluate the agreement between a mAb-based stool test (HP StAR) and the urea breath test (UBT) in monitoring (H pylori) infection after eradication therapy.

METHODS: Patients with discordant results on UBT and Hp StAR underwent endoscopy with biopsies for rapid urease test, culture, and histology to confirm H pylori status.

RESULTS: Among 250 patients (50±14 years), 240 (96.0%) had concordant UBT and Hp StAR tests with a significant correlation between DOB and A values (R = 0.87; P<0.0001). The remaining 10 (4.0%) patients had discordant tests (positive Hp StAR and negative UBT) with the Hp StAR inaccurate in five cases (false positive) and UBT inaccurate in the other five cases (false negative). The “maximal expected” sensitivity, specificity, +PV, -PV, +LR, and -LR were 91%, 100%, 100%, 97.4%, , and 8.2 respectively, for the UBT, and 100%, 97.4%, 91%, 100%, 38.8, and 0, respectively, for the Hp StAR. Overall accuracy for both tests was 98%.

CONCLUSION: Both the UBT and the Hp StAR are equally accurate in monitoring H pylori infection. Nowadays, the choice of the “best” non-invasive H pylori test in the post-treatment setting should be done not only in terms of diagnostic accuracy but also in view of cost and local facilities.

Accuracy of a new monoclonal stool antigen test in post-eradication assessment of Helicobacter pylori infection: comparison with the polyclonal stool antigen test and urea breath test

BACKGROUND AND AIM

The enzyme immunoassay based on polyclonal antibodies (HpSA) represents a valid method for the detection of Helicobacter pylori antigens in stool specimens, but some controversial results were reported in post-eradication setting. A new monoclonal enzyme immunoassay (FemtoLab H. pylori, Connex) has been developed. The present study compares the diagnostic accuracy of the two tests after eradication therapy.

PATIENTS AND METHODS

Stool samples were collected and urea breath test and endoscopy performed in 325 patients (161 F, 164 M, age 17-78 years), 4-8 weeks after standard triple eradication therapy. The FemtoLab and HpSA tests were performed in accordance with the manufacturer's protocol. H. pylori infection was confirmed if culture alone or both urease test and histology were positive and was considered absent if all three tests were negative.

RESULTS

H. pylori was eradicated in 231 patients (71.1%). Urea breath test showed the best performances with sensitivity 98.9% and specificity 99.5%. The sensitivity of FemtoLab was 88.3%, specificity 94.8%, positive and negative predictive values 87.4% and 95.2%. Corresponding HpSA values were 73.4%, 97.8%, 93.2% and 90%. Sensitivity and negative predictive value of FemtoLab were significantly better than HpSA. Adjusting the cut-offs according to a ROC curve improved not significantly the sensitivity of the two tests.

CONCLUSIONS

Urea breath test shows the best accuracy in the assessment of H. pylori infection. Between the stool tests, the FemtoLab due to its higher sensitivity is to prefer in the post-eradication assessment of H. pylori infection.

Evaluation of two enzyme immunoassays for detecting Helicobacter pylori in stool specimens of dyspeptic patients after eradication therapy

The aim of the current study was to assess the reliability of two enzyme immunoassays in detecting the Helicobacter pylori status of stool specimens of Turkish dyspeptic patients in the post-treatment period. Forty-eight patients with non-ulcer dyspepsia who were positive for H. pylori underwent a 1 week regimen of triple therapy. Stool samples of patients were obtained 2 and 6 weeks after eradication therapy and a [13C]urea breath test was performed 6 weeks after therapy in order to assess the reliability of mAb-based (Amplified IDEIA HpStAR, DakoCytomation) and polyclonal-antiserum-based (Premier Platinum HpSA, Meridian Diagnostics) stool antigen test kits and to compare their diagnostic accuracies. Using a minimum cutoff OD450 value of 0.19 for Amplified IDEIA HpStAR and 0.16 for Premier Platinum HpSA the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of the tests were determined 2 and 6 weeks after completion of eradication therapy. At both the second and the sixth week in the post-treatment period the diagnostic accuracy of Amplified IDEIA HpStAR was significantly better than the Premier Platinum's (75% versus 50%, S2=6.4; P=0.011, and 90% versus 69%, S2=6.316; P=0.012, respectively). In light of these findings the mAb-based Amplified IDEIA HpStAR has a high diagnostic accuracy for H. pylori infection in Turkish dyspeptic patients 6 weeks after completion of eradication therapy.

Helicobacter pylori stool antigen test

OBJECTIVE

Helicobacter pylori ( H.pylori ) infection is usually acquired in early childhood. Invasive techniques used for diagnosis of H.pylori infection require endoscopic examination which is expensive and inconvenient and may cause complications. The aim of this study was to evaluate the performance of a new noninvasive diagnostic method, stool antigen test for H.pylori in untreated children with recurrent abdominal pain.

METHODS

Eighty children (35 female, 45 male) who have undergone upper gastrointestinal endoscopy due to recurrent abdominal pain were included in the study. The H.pylori stool antigen test (HpSA) is based on a sandwich enzyme immunoassay with antigen detection. HpSA sensitivity, specificity, and positive and negative predictive values were determined with reference to the results of both histology and rapid urease test as a gold standard ( H. pylori status).

RESULTS

While 49 of the 80 children (61%) tested were positive for H.pylori according to the results of both histology and rapid urease test, 28 children had negative H.pylori status. Among those 49 children, 48 were found to be positive by HpSA. Of 28 patients with negative H.pylori status, 28 were H.pylori -negative also in the stool test. The sensitivity, specificity, and positive and negative predictive values of HpSA were found to be 98%, 100%, 100%, and 96.5%, respectively.

CONCLUSION

These findings have demonstrated that HpSA as a relatively simple, inexpensive and time saving noninvasive test is a reliable method for detection of H.pylori infections in children.

A combination of the Helicobacter pylori stool antigen test and urea breath test is useful for clinical evaluation of eradication therapy: a multicenter study

BACKGROUND

Helicobacter pylori stool antigen (HpSA) test is a new tool for evaluating the H. pylori infection. The present study was carried out to investigate the clinical usefulness of the HpSA test in the evaluation of eradication therapy by comparing it with the (13)C-urea breath test (UBT).

METHODS

One hundred and five patients received eradication therapy for H. pylori. After more than 8 weeks, the success of the therapy was evaluated by the HpSA test and the UBT. Concordant results were regarded as a final diagnosis, but when the results were discordant, histological examination was carried out.

RESULTS

Of the 105 patients receiving eradication therapy for H. pylori, 25 patients were regarded as H. pylori positive by the UBT and and 20 patients were regarded as H. pylori positive by the the HpSA test. Nine patients (8.6%) showed discordant results (seven cases with UBT(+) and HpSA(-), and two with UBT(-) and HpSA(+)). Five cases out of nine were ultimately judged as having a false-positive result of the UBT, and in these cases the UBT values were relatively low (below 10 per thousand). The final diagnostic accuracies of the UBT and the HpSA test were 94.3% (88.0-97.9%; 95% CI) and 97.1% (91.9-99.4%), respectively. When we used the HpSA test in cases with weakly positive UBT values, we were able to diagnose the correct status of H. pylori infection after eradication in 99% of all patients (94.8-100.0%).

CONCLUSION

The HpSA test is a useful tool for the evaluation of eradication therapy and a combination of the HpSA test and UBT is clinically recommended.

Evaluation of stool antigen test for Helicobacter pylori infection in asymptomatic children from a developing country using 13C-urea breath test as a standard

OBJECTIVE

Prevalence of asymptomatic Helicobacter pylori infection is very high in infants and children in developing countries. C urea breath test (UBT) is a reliable non-invasive diagnostic test for H. pylori infection in children that avoids invasive endoscopy. We compared a newly introduced H. pylori stool antigen test (with a high sensitivity and specificity in symptomatic children) with UBT in asymptomatic children mostly 1-5 years old, from a population with a high prevalence of infection.

METHOD

Eighty six asymptomatic children (42 boys and 44 girls) were tested for H. pylori infection using the UBT and a stool antigen test (HpSA) based on a sandwich enzyme immunoassay for antigen detection.

RESULTS

Forty five of the eighty-six (52.3%) children tested positive for H. pylori using the breath test. In 34 of these forty-five children, H. pylori antigen was detected in stool (sensitivity = 75.6%, 95% CI = 63 to 88%). Of the 50 of 86 (58%) children positive by HpSA test, 34 were positive for breath test. Of the 41 children with negative UBT test 25 were negative for stool antigen test (specificity = 61%, 95% CI = 46 to 76%).

CONCLUSION

The sensitivity and specificity of the new stool antigen test are lower in asymptomatic children with high H. pylori prevalence rate compared to those reported for children with gastrointestinal symptoms. Its usefulness is limited for diagnosis in an asymptomatic child with H. pylori infection.

Evaluation of the stool antigen test for Helicobacter pylori in children and adolescents

The stool antigen test for Helicobacter pylori is a noninvasive immunoassay to diagnose active infection with Helicobacter pylori in human fecal samples. Its performance in children and teenagers has been tested in some developed countries, showing a sensitivity and specificity above 90%, however, its accuracy in developing countries and in children under 6 years is not well established. To determine the accuracy of the test for diagnosing Helicobacter pylori infection in children and teenagers, we evaluated 133 patients (4 months to 17 years old). The gold standard was a positive culture or positive histology and rapid urease test. The test was done according to the manufacturer's instructions. However, modifications were introduced for better reproducibility. Samples were analyzed twice and results are expressed as optical density (OD) determined spectrophotometrically at 450 nm. HpSA was considered positive at OD > or =0.160 and negative at OD <0.140. One hundred twenty-seven of the 133 (95.5%) patients were included. There were no infected infants. The test showed a 94.6% sensitivity (95% CI: 90.6-98.5) and a 96.5% specificity (95% CI: 93.3-99.7). At ages 2 to 6 years the specificity was 96.4% (95% CI: 85.1-99.2) and the sensitivity was 80.0% (95% CI: 64.8-89.7), at ages 6 to 10 years the sensitivity was 100.0% and the specificity 95.7%, and above 10 years the sensitivity and specificity were 100.0%. We conclude that the test is efficient in adolescents and children, however there is a need for further studies with a greater number of patients for evaluation of its accuracy in infants.

Accuracy of Helicobacter pylori stool antigen for the detection of Helicobacter pylori infection in dyspeptic patients

AIM: The premier platinum Helicobacter pylori (H pylori) stool antigen (HpSA) test is an enzyme immunoassay (EIA) that detects an H pylori antigen present in human stools. However, at present there is no uniformity about the cut off level required to consider the test as positive or negative. So we need the cut off level for our local population. The aim of this study was to evaluate the HpSA for the detection of H pylori infection in dyspeptic patients and to determine the sensitivity, specificity of the HpSA test in the diagnosis of H pylori infection, as compared to other standardized diagnostic techniques.

METHODS: Sixty-three dyspeptic patients were selected from patients who came to the Division of Gastrointestinal Clinic in Cipto Mangunkusumo Hospital, Jakarta, Indonesia. H pylori infection was confirmed in all patients by histology and rapid urease test (CLO test). Positive results for H pylori were based on positive results from both rapid urea test and microscopic detection of H pylori. Stool specimens were analyzed for H pylori antigen using HpSA immunoassay.

RESULTS: A total 63 patients consisted of 31 (49.2%) males and 32 (50.8%) females ranging in ages between 16 and 73 years with a mean age of 42.4±15 years. The mean age of men was 43.2±15.7 years and women was 41.6±14.4 years. Endoscopic findings in this study included gastric cancer 1.6%, peptic ulcer 4.8%, duodenal ulcer 7.9%, esophagitis 6.3%, gastritis 77.7%, and gastroduodenitis 4.8%. According to the predefined study criteria, 6 (9.5%) of 63 patients were positive for H pylori. In the diagnosis of infection, the area under the receiver operating characteristic (ROC) curve for the HpSA test was 0.722 (95% CI, 0.518-0.927). Using a cut-off value of 0.274 instead of 0.16 (as recommended by the manufacturer) the sensitivity and the specificity were 66.7% and 78.9% respectively.

CONCLUSION: The HpSA stool test, using a cut-off value of 0.274, may be useful for the primary diagnosis of H pylori infection, its specificity is similar to other standard tests but its sensitivity was lower.

Evaluation of stool antigen detection for diagnosis of Helicobacter pylori infection in adults

OBJECTIVE

The aims of this study were to evaluate the performance of Helicobacter pylori stool antigen test in the diagnosis of H. pylori infection.

METHOD

The study included 63 out patients attending the ULB-Lothier Clinic between January 1 and July 31, 2002. They underwent an upper endoscopy, as well as biopsies for histological examination and for culture of H. pylori. Stool samples of these patients were collected either the day of the endoscopy or within 24 hours and tested for H. pylori antigen (HpSA Test)

RESULTS

The mean age of study patients included 29 men and 34 women was 51(+/- :16) years. H. pylori infection was detected in 29 cases (46 %) by culture and histology, and in 31 cases (49.2 %) by detection of the antigen in the feces. In 27 patients, all methods were positive whereas 5 in they provided discrepant results. Compared to the reference methods (culture and histology), the HpSA test had a sensitivity of 96.5% and a specificity of 91.2%. PPV of 90.3% and NPV of 96.8%.

CONCLUSION

The good correlation found between the results of the HpSA test and the methods based on endoscopy supports its use as an alternative to invasive methods of diagnosis of H. pylori infection and therapeutic follow-up.

Evaluation of Helicobacter pylori stool antigen test before and after eradication therapy

BACKGROUND AND AIM

The Helicobacter pylori stool antigen (HpSA) test is useful for initial diagnosis of H. pylori infection, but there is disagreement regarding its diagnostic accuracy after eradication therapy. The aim of the present study was to evaluate the diagnostic accuracy of the HpSA test before and after eradication therapy.

METHODS

One hundred and thirty-six patients underwent upper gastrointestinal endoscopy with biopsies for the diagnosis of H. pylori infection using culture, histology and the rapid urease test. Fifty-four H. pylori-positive patients were treated with 1-week triple therapy. Six to 10 weeks after the end of therapy, the patients underwent re-endoscopy and received the same biopsy-based methods. In addition, the 13C-urea breath test was performed. The HpSA test was performed before and 6-10 weeks after the end of therapy. In 23 patients, the HpSA test was also performed at the end of therapy.

RESULTS

Before therapy, the sensitivity and specificity of the HpSA test was 98.3% (95% confidence interval (CI): 95.9-100%) and 95.0% (95% CI: 75.1-99.9%), respectively. At the end of therapy, the HpSA tests were all negative both for eradication and non-eradication patients. The sensitivity and specificity of the HpSA test after eradication therapy were 90% (95% CI: 55.5-99.7%) and 97.7% (95% CI: 93.3-100%), respectively.

CONCLUSIONS

The HpSA test is a useful method for the diagnosis of H. pylori infection before and after eradication therapy.

Review article: clinic-based testing for Helicobacter pylori infection by enzyme immunoassay of faeces, urine and saliva

Enzyme immunoassays have been used to detect Helicobacter pylori infection in human body materials such as faeces, urine and saliva. The stool antigen assay (HpSA), which uses polyclonal anti-H. pylori antibody as a capture reagent, has been widely used in the pre-treatment diagnosis of the infection in adults and children. Although the assay has the potential for monitoring eradication therapy, there are controversies over its use, especially at an early stage after treatment. The efficacy of the stool antigen assay can be modified by using monoclonal antibodies towards well characterized H. pylori faecal antigens. Two types of enzyme immunoassays (enzyme-linked immunosorbent assay [ELISA] and immunochromatography) have been used to detect antibodies to H. pylori in urine. Immunochromatography of urine is a rapid assay well suited for epidemiological studies. The salivary ELISA, used in a number of studies, has shown inconsistent results with less than optimum sensitivity and specificity. Urinary and salivary immunoassays may not distinguish between past and present infections, thus limiting their potential to monitor eradication therapy.

Antigen stool test for assessment of Helicobacter pylori infection in patients with upper gastrointestinal bleeding

BACKGROUND

Re-bleeding of Helicobacter pylori-associated peptic ulcer disease is reduced by H. pylori eradication.

AIM

To validate a non-invasive test, the Premium Platinum HpSA stool test, in patients with upper gastrointestinal bleeding.

METHODS

Stool samples of consecutive patients with relevant bleeding from gastric or duodenal ulcers or erosions were collected at initial endoscopy and during the following week. Samples were assessed using the HpSA test. H. pylori status was defined by three biopsy-based reference methods: culture, rapid urease test and histology. It was positive if culture was positive or if rapid urease test and histology were positive.

RESULTS

One hundred and fourteen patients (mean age, 66 years) were included. In accordance with the definition, 56 (49%) were H. pylori positive. The sensitivity and specificity of the first stool sample were 84% and 90%, respectively. The respective values for two samples from consecutive days were 91% and 86%. In comparison with a serum immunoglobulin G antibody enzyme-linked immunoabsorbent assay, the HpSA test showed superior specificity.

CONCLUSIONS

The diagnostic accuracy, in particular the sensitivity, of the HpSA stool test is reduced by upper gastrointestinal bleeding. The positive predictive value of 89%, however, justifies the initiation of eradication therapy on the basis of a positive stool test. A negative test result should be confirmed by a further diagnostic method.

Stool antigen assay (HpSA) is less reliable than urea breath test for post-treatment diagnosis of Helicobacter pylori infection

BACKGROUND

The diagnostic yield of the stool antigen test (HpSA) in evaluating the results of Helicobacter pylori eradication therapy is controversial, but many studies have used only the 13C-urea breath test (13C-UBT) as a gold standard which has greatly reduced their relevance.

AIM

To compare the reliability of HpSA and 13C-UBT in patients post-treatment using biopsy-based methods as reference tests.

METHODS

A total of 100 consecutive dyspeptic patients (42 male and 58 female; mean age, 56 +/- 18 years) were enrolled in our study. All patients were H. pylori positive on the basis of at least two biopsy-based methods, and underwent 1 week of treatment with various triple therapies. They were again endoscoped 4 weeks after completing therapy and six biopsy specimens were taken from the gastric antrum and corpus for rapid urease test, histology and culture. HpSA and 13C-UBT were also performed within 3 days of the second endoscopy.

RESULTS

On the basis of biopsy-based tests, infection was eradicated in 77 patients but continued in 23. Three false negatives were observed with HpSA and two with 13C-UBT. In contrast, the number of false positives was significantly higher (P < 0.01) with HpSA than with 13C-UBT (nine vs. one), confirming the lower specificity of the former test. The overall accuracy of HpSA was 88% vs. 97% for 13C-UBT (P < 0.02).

CONCLUSIONS

HpSA has lower diagnostic value than 13C-UBT in the evaluation of the outcome of anti-H. pylori therapy. 13C-UBT remains the first-line diagnostic method to monitor eradication results. The use of HpSA should be reserved for those settings in which 13C-UBT is not available.

Efficacy of enzyme immunoassay for the detection of Helicobacter pylori antigens in frozen stool specimens: local validation

AIM

To investigate the efficacy of measurement of Helicobacter pylori stool antigen (HpSA) using stored frozen stool specimens, and to assess whether there were factors affecting efficacy in Hong Kong.

METHODS

Patients undergoing upper endoscopy at Tuen Mun Hospital were recruited. Stool samples were saved for HpSA testing and questionnaires were completed. Stool samples were frozen immediately upon receipt and stored at -70 degrees C until tested. HpSA results were compared with rapid urease test and histology.

RESULTS

One hundred and eighty-one patients were recruited. One hundred and seventy-eight patients were suitable for analysis. Eighty-three were H. pylori positive and 95 were H. pylori negative. The mean duration of storage of the stool samples was 120 days (range, 40-225 days). The sensitivity, specificity and positive and negative predictive values were 84.3%, 97.9%, 97.2% and 88.6%, respectively. In patients with a false negative HpSA test, there was a significant delay in collecting the stool specimen after endoscopy when compared with those with a true positive HpSA test (4.2 vs. 2.3 days; P < 0.05). However, the duration of storage of the specimens was not longer, and consumption of coffee or tea and smoking habits were similar.

CONCLUSIONS

HpSA testing showed good sensitivity and specificity, even with frozen stool samples stored for up to 225 days. The efficacy was not affected by coffee, tea or smoking.

Catalase, a specific antigen in the feces of human subjects infected with Helicobacter pylori

Recently, we reported the production of three new monoclonal antibodies with high specificity for a Helicobacter pylori antigen suitable for diagnosis of H. pylori infection. The aim of the present study was to identify the antigen recognized by these monoclonal antibodies concerning both H. pylori and the feces of human subjects infected with H. pylori. The cellular antigen was purified from an H. pylori cell extract by immunoaffinity column chromatography with the monoclonal antibody as a ligand. The amino-terminal amino acid sequences (eight residues) of the purified antigen and H. pylori catalase were the same. The molecular weights of native and subunit, specific catalase activity, and UV and visible spectra of the purified antigen were in good agreement with those of H. pylori catalase. The human fecal antigens were purified from two fecal samples of two H. pylori-positive subjects by ammonium sulfate precipitation, CM-Sephadex C(50) chromatography, and the same immunoaffinity chromatography used for the H. pylori cellular antigen. The fecal antigens had catalase activity. The amino-terminal amino acid sequences (five residues) of the human fecal antigen and H. pylori catalase were the same. The monoclonal antibodies reacted with the native cellular antigen, but did not react with the denatured antigen, human catalase, and bovine catalase. The results show that the target antigen of the monoclonal antibodies is native H. pylori catalase and that the monoclonal antibodies are able to specifically detect the antigen, which exists in an intact form, retaining the catalase activity in human feces.

[Stool antigen test for initial Helicobacter pylori diagnosis and for confirmation of eradication after therapy]

BACKGROUND

: Recently, a new diagnostic method based on the detection of Helicobacter pylori antigen in stools (HpSA) has been developed. Our aim was to prospectively evaluate the accuracy of HpSA both in the initial diagnosis of H. pylori infection and in the confirmation of the eradication after treatment.

PATIENTS AND METHOD

Thirty dyspeptic patients were prospectively evaluated. During endoscopy, biopsies for histology and rapid urease test were obtained, and a 13C-urea breath test was performed. HpSA was determined by radioimmunoassay(Premier Platinum HpSA). Infected patients were administered H.pylori eradication treatment, and breath test and HpSA were performed again 4 weeks after finishing the therapy. Gold standard for H. pylori infection pre-treatment was based on rapid urease test, histology and breath test, whereas 13C-urea breath test was considered the post-treatment gold standard.

RESULTS

Pre-treatment H. pylori prevalence was 57%. Eradication was achieved in 85% of patients. The area under ROC curve for HpSA pre-treatment was 0.98. Cut-off points with best pre-treatment diagnostic accuracy were those between 0.10 and 0.12: positive likelihood ratio (LR), negative LR, 0.06; 94% sensitivity (95% CI, 73-99%),100% specificity (75-100%), 100% positive predictive value (81-100%)and 93% negative predictive value (66-100%). After treatment,the area under ROC curve was 1, and all cut-off points between 0.10 and 0.18 had 100% diagnostic accuracy. HpSA levels decreased from 0.94 (0.9) to 0.08 (0.02) (p < 0.01) in patients withH. pylori eradication success.

CONCLUSIONS

HpSA test can be considered an accurate, non-invasive method for the diagnosis of H. pylori infection both inuntreated patients and in the confirmation of H. pylori eradication after treatment.

Different effects of short-term omeprazole, lansoprazole or pantoprazole on the accuracy of the (13)C-urea breath test

BACKGROUND

Proton pump inhibitors may interfere with the accuracy of the (13)C-urea breath test, but little information is available on the effect of standard doses of various proton pump inhibitors on this test.

AIM

To evaluate the effect of short-term standard doses of omeprazole, lansoprazole and pantoprazole on the accuracy of the standardized (13)C-urea breath test.

METHODS

A total of 124 patients with Helicobacter pylori infection, diagnosed on the basis of gastric histology, rapid urease test and (13)C-urea breath test, were studied. These patients received omeprazole, 20 mg/day, lansoprazole, 30 mg/day, or pantoprazole, 40 mg/day, for 2 weeks according to a randomized protocol. (13)C-Urea breath test was repeated on days 4, 7 and 14 while on therapy and 7 days after proton pump inhibitor withdrawal.

RESULTS

Of the patients receiving omeprazole and lansoprazole, 30% (12/40) and 20% (8/41), respectively, became (13)C-urea breath test negative during therapy, compared with none of the 42 patients treated with pantoprazole (P < 0.05). All the false negative (13)C-urea breath test results returned to positive within 1 week of drug withdrawal, with a mean recovery to 84.7 +/- 15.6% of baseline delta(13)CO(2).

CONCLUSIONS

Short-term omeprazole and lansoprazole interfere with the 13C-urea breath test, although a return to positive test results invariably occurs within 1 week of proton pump inhibitor withdrawal. In contrast, the accuracy of the (13)C-urea breath test does not appear to be significantly impaired by short-term pantoprazole, which therefore may not necessarily be withdrawn before this test.

Helicobacter pylori-associated peptic ulcer disease in older patients: current management strategies

The incidence of peptic ulcer and its severe complications, i.e. bleeding or perforation, is increasing in elderly patients worldwide. The prevalence of Helicobacter pylori infection in patients with peptic ulcer aged over 65 years has been reported to range from 58 to 78%. However, in elderly patients hospitalised for ulcer disease, the rate of diagnostic screening or treatment for H. pylori infection was less than 60%, and only 50 to 73% of patients who had a positive H. pylori test were treated with antibacterials. The eradication of H. pylori infection is known to be of proven benefit for elderly patients with H. pylori-associated ulcer disease. Significant improvement of the clinical outcome, and reduction of ulcer recurrences, symptoms and histological signs of ulcer-associated chronic gastritis activity, as well as decreased costs in elderly healthcare, all result from successful therapy. Proton pump inhibitor (PPI)-based triple therapy regimens including clarithromycin, amoxicillin and/or nitroimidazoles are highly effective and well tolerated in elderly patients, particularly if therapy is of a short duration and low doses of both the PPI and clarithromycin are used. Resistance of H. pylori to antibacterials and low compliance are the major reasons for treatment failure. Surveillance of H. pylori susceptibility to antibacterials at the regional level and enhanced compliance programmes give promising results that suggest new approaches to anti-H. pylori treatment, especially in elderly patients. The role of H. pylori infection in nonsteroidal anti-inflammatory drug (NSAID)-related peptic ulcer still remains controversial. At present, no clear evidence supports the testing and treatment of H. pylori infection for the prevention of drug-related peptic ulcer in elderly patients receiving an NSAID or aspirin (acetylsalicylic acid). After therapy, elderly patients with peptic ulcer may be re-evaluated by invasive methods, i.e. endoscopy and gastric biopsies. or by noninvasive methods. In elderly patients, the 13C-urea breath test demonstrated significantly higher sensitivity, specificity and diagnostic accuracy for detecting H. pylori infection than anti-H. pylori antibodies.

Production and application of new monoclonal antibodies specific for a fecal Helicobacter pylori antigen

The aim of the present study was to establish monoclonal antibodies that could be used to produce a diagnostic test composed of one kind of monoclonal antibody recognizing a fecal Helicobacter pylori antigen. The need to develop such a test arose from disadvantages of the diagnostic test that uses a polyclonal antibody or plural kinds of monoclonal antibodies, such as the lower specificity for H. pylori antigen and the difficulty of reproduction with consistent quality. Mice were immunized with sonicated cells of the coccoid form of H. pylori, and fecal samples from H. pylori-positive subjects were screened by a direct sandwich enzyme immunoassay (EIA) for antibody production from 32 hybridoma clones. The three stable clones produced antibodies (21G2, 41A5, and 82B9) that reacted with the same soluble antigen. Gel filtration chromatography showed that the molecular masses of the cellular antigen and the fecal antigen were the same, 260 kDa. The antigen was labile in response to sodium dodecyl sulfate and heat treatments. A single-step direct sandwich EIA using a single monoclonal antibody, 21G2, was developed. The EIA could detect the antigen in 41 H. pylori clinical isolates and in fecal samples from seven H. pylori-positive subjects. Several kinds of Helicobacter species (Helicobacter felis, Helicobacter hepaticus, Helicobacter mustelae, and Helicobacter cinaedi) except H. pylori, major bacteria in feces (Campylobacter jejuni, Bacteroides vulgatus, Bifidobacterium breve, Bifidobacterium infantis, and Escherichia coli), and fecal samples from six H. pylori-negative subjects showed negative results. These results indicate that the new monoclonal antibodies and the new specific EIA would be useful as a noninvasive method of diagnosis of H. pylori infection.

Diagnosis of Helicobacter pylori infection

A number of invasive and non-invasive techniques are available for the diagnosis of infection with Helicobacter pylori. These can be used to establish whether infection is present and to confirm that eradication has been achieved after treatment. Invasive techniques require biopsy of the gastric mucosa; such techniques include histology, bacterial culture, the rapid urease test and the polymerase chain reaction (PCR) technique. The principal non-invasive techniques are the 13C-urea breath test and serological assays in serum or saliva samples. Histological examination of gastric biopsy samples should be mandatory at the initial presentation of the patient because it also gives insight on the status of the gastric mucosa. The rapid urease test can be used to give a rapid diagnosis of infection. Eradication should also be confirmed by histological examination, though other sensitive tests such as bacterial culture, PCR or the 13C-urea breath test may also be used.

Posttreatment follow-up of Helicobacter pylori infection using a stool antigen immunoassay

The Helicobacter pylori stool antigen enzyme immunoassay (HpSA) was evaluated during posttreatment follow-up of patients in a country with a very high prevalence of H. pylori infection. From among 273 dyspeptic individuals (18 to 55 years) initially recruited from a shantytown in Lima, Peru, 238 participants who met the inclusion criteria and were suspected to be H. pylori positive based on (14)C urea breath test (UBT) results underwent endoscopy. Participants with endoscopy-proven infections received standard eradication therapy and were monitored by UBT and HpSA at 1 month following treatment and at 3-month intervals for 9 months posttreatment. A second endoscopy was performed if UBT results showed evidence of treatment failure or H. pylori recurrence. Biopsy results were considered the "gold standard" in all analyses. Among patients who underwent endoscopy, HpSA had a pretreatment sensitivity of 93%. Two-hundred thirty patients completed the treatment regimen, of whom 201 (93%) were considered to have had successful treatment outcomes based on a negative follow-up UBT. Thirty-two patients with UBT-defined treatment failures or H. pylori recurrences at any point during the 9-month follow-up underwent a second endoscopy. In the posttreatment setting, HpSA had an overall sensitivity of 73% and a specificity of 67%. Agreement between UBT and HpSA diminished throughout the follow-up. Among 14 participants in whom HpSA remained positive at 1 month following treatment despite UBT evidence of treatment success, 12 (86%) became HpSA negative within 3 months posttreatment. Although this study confirmed the validity of the HpSA in the initial assessment of dyspeptic patients, the test demonstrated a reduced overall accuracy in the detection of treatment failures and H. pylori recurrences during 9 months of posttreatment follow-up. Furthermore, in some patients it may take up to 3 months after successful eradication for antigen shedding to diminish to levels within the negative HpSA range.

Validity of a Helicobacter pylori stool antigen assay for the assessment of H. pylori status following eradication therapy

BACKGROUND

A Helicobacter pylori stool antigen (HpSA) test has been proposed as a valid alternative to the 13C-urea breath test (13C-UBT) for the non-invasive detection of H. pylori infection in primary diagnosis. Published reports show conflicting results with regard to the test's diagnostic accuracy after eradication therapy. The aim of the present study was to assess the diagnostic value of the HpSA test and to determine the optimal discriminating cut-off value in patients following H. pylori eradication therapy.

METHOD

Stool samples were collected and the 13C-UBT was performed in 113 patients 4-6 weeks after eradication therapy. A validated test protocol for the 13C-UBT was used. Stool specimens were analysed with the Premier Platinum HpSA enzyme immunoassay (EIA). A receiver operator characteristics (ROC) analysis was performed to define the optimal cut-off value on the basis of the results of the 13C-UBT.

RESULTS

The results of the 13C-UBT showed that H. pylori eradication was successful in 83/113 (73%) patients. According to the manufacturer, the cut-off value for the HpSA test is 0.14 optical density, but this does not appear to be valid after eradication therapy (sensitivity 76.7%, specificity 98.8%). On the basis of ROC analysis, the optimal cut-off value after therapy was determined to be 0.11 optical density, giving a sensitivity of 93.3% and a specificity of 93.9%.

CONCLUSION

The HpSA test is a valid test for the assessment of H. pylori status after eradication therapy, provided an adjusted cut-off value is applied.

Post-treatment diagnostic accuracy of a new enzyme immunoassay to detect Helicobacter pylori in stools

BACKGROUND

Helicobacter pylori has attracted increasing attention among gastroenterologists because of its pathogenic potential, stimulating the search for non-invasive diagnostic tests.

AIMS

In this study the efficacy of a new enzyme immunoassay designed to detect H. pylori antigens in stools (HpSA) was evaluated before and after eradication therapy.

METHODS

HpSA was performed on stool samples collected from 268 patients whose H. pylori status was defined on the basis of concordant results for the (13)C-urea breath test, rapid urease test and histology. The H. pylori-positive patients were treated with a 1-week triple therapy to eradicate the infection. One (T30) and 3 months (T90) after the end of therapy, (13)C-urea breath test and HpSA were repeated in the treated patients.

RESULTS

The overall diagnostic accuracy of HpSA at T30 (83%, 95% confidence interval (CI) 77--89%) was significantly lower in comparison to the values obtained at baseline (94%, 95% CI: 91--97%) and at T90 (97%, 95% CI: 94--99%). No significant difference was found between the diagnostic accuracy of HpSA at baseline and at T90 (P=0.253).

CONCLUSIONS

The present data suggest that HpSA provides a low diagnostic accuracy when used shortly after treatment. It needs a longer period of follow-up (8--12 weeks) to reach a reliability comparable to the (13)C-urea breath test.

[Helicobacter pylori infections: antigen detection in stool samples]

BACKGROUND

The aim of this study is to evaluate a new diagnostic test to detect Helicobacter pylori antigen in stool samples (HpSA), and compare the results with those obtained by standard techniques (rapid urease test,culture, histological examination of gastric biopsy specimens,13C-urea breath test and serology), in a paediatric population with gastrointestinal symptomatology.

PATIENTS AND METHODS

Sixty patients with dyspeptic symptoms (37 females and 23 males;mean age 10.9 years) attending the Gastroenterology Service were included in the study. Exclusion criterium was previous treatment with proton pump inhibitors, bismuth compounds or antibiotics. Rapid urease test, culture and histologic study of gastric biopsies,13C-urea breath test and serology, as well as HpSA, were performed to all patients.

RESULTS

Forty seven patients were considered infected by H.pylori on the basis of bacterium isolation and 13C-urea breath test positivity. HpSAwas detected in 45 of the 47 H.pylori positive patients(95.7%). There were no HpSA false positive.

CONCLUSION

Our results show that this new test is highly sensitive (95%) and specific(100%) for detection of H. pylori infection. It has some advantages over other non invasive techniques: it is easy to perform,requires no blood samples and its cost is lower than that of 13C-urea breath test.

Usefulness of Helicobacter pylori stool antigen test to monitor response to eradication treatment in children

BACKGROUND

The monitoring of the results of eradication treatment is a crucial step for patients with Helicobacter pylori gastritis. A non-invasive test for H. pylori antigens in stools (HpSA) was recently validated for children.

AIM

To evaluate the accuracy of HpSA in monitoring eradication treatment in children.

METHODS

In 60 children, H. pylori gastritis was diagnosed by endoscopy and the 13C-urea breath test. The children were treated and returned for a follow-up (13)C-urea breath test 6 weeks after the end of treatment. Children were considered cured when the (13)C-urea breath test was negative. Stool were collected at baseline, and at 2 and 6 weeks. Stool antigens were measured by HpSA.

RESULTS

According to (13)C-urea breath test, 6 weeks after the end of treatment 49 children were cured and 11 were still H. pylori-positive. The sensitivity and specificity of HpSA on stools collected 2 weeks after therapy were 100%. At 6 weeks specificity was 93.9 and sensitivity 100%. Results by visual reading were concordant with the plate-reader in all but two cases at baseline.

CONCLUSIONS

HpSA is accurate for monitoring treatment in children as early as 2 weeks after therapy, when information is most useful and unachievable with other tests. Results by visual reading are accurate, and this can make the test cheaper and more practical.

Accuracy of the stool antigen test in the diagnosis of Helicobacter pylori infection before treatment and in patients on omeprazole therapy

AIM

To evaluate the Helicobacter pylori stool antigen (HpSA) test in the assessment of H. pylori infection and the effect of omeprazole treatment on its accuracy.

METHODS

Study 1: 140 dyspeptic patients were enrolled in the study and defined as H. pylori positive if histology and rapid urease test, or culture alone were positive. HpSA was performed on all patients and 13C-urea breath test (UBT) on 87. Study 2: 75 patients testing positive using both UBT and HpSA, were given omeprazole 20 mg for 2 weeks (Group A) or omeprazole 40 mg for 2 weeks (Group B), or OAC for 1 week (group C). A Helicobacter pylori stool antigen test was performed on all patients on days 3, 5, 7 and 14 during treatment, and also on days 7 and 14 post-treatment in groups A and B. UBT was performed in groups A and B on days 7 and 14 during treatment, and days 7 and 14 post-treatment.

RESULTS

80/140 patients were H. pylori positive. The sensitivity and specificity of HpSA were 93.8 and 90%, similar to UBT (93.9 and 92.1%). Omeprazole significantly reduced both HpSA and UBT values, resulting in a decreased accuracy. Of 25 patients receiving 20 mg omeprazole, HpSA gave 5 and 6 false negatives after 7 and 14 days treatment respectively, while UBT gave 4 and 7 false negatives after 7 and 14 days treatment. Of 25 patients receiving 40 mg omeprazole, HpSA gave 7 and 9 false negatives after 7 and 14 days of treatment, while UBT gave 8 and 9 false negatives after 7 and 14 days of treatment. Two weeks after stopping omeprazole treatment, the HpSA and UBT were positive in all cases.

CONCLUSIONS

The Helicobacter pylori stool antigen test is valuable in the assessment of H. pylori infection. Short-term omeprazole treatment decreases the accuracy of both HpSA and UBT in a similar manner.

Review article:invasive and non-invasive tests for Helicobacter pylori infection

There are two general ways in which a diagnosis of infection by Helicobacter pylori can be made: by using either an invasive or non-invasive procedure. The invasive procedures involve an endoscopy and biopsy. A biopsy is essential because often the mucosa may appear macroscopically normal but nevertheless be inflamed. A biopsy is obtained by histological examination, culture, polymerase chain reaction or detection of the presence of urease activity in biopsy material. The non-invasive tests that can be used to diagnose the infection are serology, detection of labelled metabolic products of urea hydrolysis in the breath (13CO2, 14CO2), the urine or the blood, and detection of H, pylori antigen in a stool specimen. At present no single test can be relied upon to detect definitely colonization by H. pylori, and a combination of two is recommended if this is feasible. The choice of the test to be used is not straightforward and may vary according to the clinical condition and local expertise.

Evaluation of a PCR primer based on the isocitrate dehydrogenase gene for detection of Helicobacter pylori in feces

In order to improve detection and identification of Helicobacter pylori in highly contaminated samples, we evaluated new specific primers based on the DNA base sequence within the isocitrate dehydrogenase (icd) gene to amplify a 1,200-bp DNA segment. The specificity of the icd primer was tested against DNA derived from various bacteria, including 7 Helicobacter species and a panel of 1 gram-variable, 2 gram-positive, and 16 gram-negative bacteria, as well as DNA from houseflies and feces from H. pylori-negative patients. The primers permitted the detection of all clinical H. pylori isolates tested, but no reactions were observed with negative controls. Several procedures for DNA extraction from feces were evaluated using PCR with icd primers. The lower limits of detection of H. pylori DNA from two different sources containing the same number of H. pylori organisms, a pure culture and feces spiked with H. pylori, were established for each extraction method tested. The results were 8.0 x 10(3) CFU/ml for cultures of pure H. pylori, and 8.0 x 10(6) CFU/ml for H. pylori from feces, using the phenol-chloroform method; 8.0 x 10(2) and 7.0 x 10(3) CFU/ml, respectively, for a glass matrix and chaotropic solution protocol; 8.0 x 10(2) and 7.0 x 10(3) CFU/ml, respectively, for the QIAamp tissue kit; and 5.0 x 10(2) and 5.0 x 10(3) CFU/ml, respectively, for the XTRAX DNA extraction kit. We conclude that the use of the icd gene as a primer for PCR represents a specific and sensitive assay for detection of H. pylori in highly contaminated samples.

Two enzyme immunoassays and PCR for detection of Helicobacter pylori in stool specimens from pediatric patients before and after eradication therapy

This study of pediatric patients was intended to determine the suitability of stool PCR and two antigen enzyme immunoassays (EIAs; Premier Platinum HpSA and the novel FemtoLab H. pylori), which detect Helicobacter pylori antigens in feces, as pretreatment diagnostic tools and especially as posttreatment control. Forty-nine H. pylori-infected children with dyspepsia received eradication therapy. Successful treatment was determined by a negative [(13)C]urea breath test 4 and 12 weeks after discontinuation of therapy. Fecal specimens were collected prior to eradication therapy as well as 4 weeks after the end of treatment. Successfully treated children delivered stool samples at 6, 8, and 12 weeks posttreatment also. Specimens were examined by seminested PCR and Premier Platinum HpSA and were reexamined by both EIAs as soon as FemtoLab H. pylori was available. In the first test series, the overall sensitivities of PCR and Premier Platinum HpSA were 93.0 and 91.1%, respectively. With specimens collected at 4 weeks after treatment, the respective specificities were 68.8 and 79.3%. After longer follow-up periods, however, they gradually increased to 100 and 96.9%, respectively. In the new test series, Premier Platinum HpSA delivered a considerably lower number of false-positive results (4 versus 18), indicating intertest variations. The overall test sensitivity was 94.6%, and the overall specificity was 97.5%. FemtoLab H. pylori showed an excellent performance with an overall sensitivity and specificity of 98.2 and 98.1%, respectively. Thus, in contrast to PCR, both EIAs were shown to be suitable for early posttreatment control.

Diagnostic accuracy of a new non-invasive enzyme immunoassay for detecting Helicobacter pylori in stools after eradication therapy

BACKGROUND

Helicobacter pylori eradication therapy has been commonly performed for patients with peptic ulcer. An inexpensive, reliable, non-invasive test would be useful for evaluation of the effectiveness of eradication therapy.

AIM

To evaluate the diagnostic potential of a new non-invasive enzyme immunoassay (HpSA) for H. pylori antigen in stools.

METHODS

A total of 112 peptic ulcer patients with H. pylori infection (82 male, 30 female; age range 22-81 years, mean 54 years) received a course of eradication therapy. Four weeks after the end of the therapy, stool samples were collected from all patients and tested using the HpSA. The diagnostic accuracy of the HpSA EIA was evaluated in comparison with the results of a 13C-urea breath test.

RESULTS

The diagnostic sensitivity of HpSA EIA after eradication therapy was 90%, the specificity 98%, the positive predictive value 82% and the negative predictive value 99%.

CONCLUSION

The HpSA stool test is potentially useful for the diagnosis of H. pylori infection 4 weeks after the end of eradication therapy.