Comparison of three stool antigen tests for Helicobacter pylori detection

BACKGROUND: Active Helicobacter pylori infection can be diagnosed by invasive (biopsy based) or non-invasive methods, such as stool antigen testing. AIMS: To compare three stool antigen enzyme immunoassay kits--Premier Platinum Hp SA, FemtoLab Cnx, and Hp Ag--with biopsy based methods for the detection of H pylori in previously undiagnosed patients. METHODS: One hundred and eleven adults with dyspepsia referred for endoscopy provided a stool sample for testing and had biopsies taken. Patients were considered H pylori positive if two out of three invasive tests were positive or if culture alone was positive. RESULTS: The sensitivities and specificities of the Premier Platinum Hp SA, FemtoLab Cnx, and Hp Ag stool antigen kits when compared with biopsy based diagnosis were, 63.6%, 88.0%, and 56.0% and 92.6%, 97.6%, and 97.6%, respectively. CONCLUSIONS: FemtoLab Cnx may be considered as an alternative to urea breath testing in the initial diagnosis of patients with dyspepsia who do not require immediate endoscopy. Stool testing has the potential advantages of being simple to perform, relatively cheap, and samples can be submitted directly from primary care.     

Which test is best for Helicobacter pylori? A cost-effectiveness model using decision analysis

GPs face a potential dilemma in deciding which test to use for detection of Helicobacter pylori. For patients with dyspepsia, the National Institute for Health and Clinical Excellence (NICE) advises primary care practitioners to adopt a 'test and treat' policy before considering a referral for gastroscopy. There are many ways of testing: serology, urea breath test, and faecal antigen test. NICE does not advocate any preferred single test for detecting H. pylori. In the current study a multi-stakeholder 2-day workshop was established to agree and populate a cost-effectiveness decision analysis model. The aim was to analyse the three types of tests available for H. pylori and to determine which is the most practical and cost effective. Agreement on the costs and diagnostic values to be entered into the decision-analytic model was achieved. Results indicate that the faecal antigen test was the most effective in terms of true outcomes and cost. One thousand virtual patients were allocated to each of the three tests. Serology had 903, urea breath test had 961, and the faecal antigen test had 968 true positive outcomes. Data indicate that the faecal antigen test is the preferable strategy for diagnosis of H. pylori in primary care. This has implications for implementing new testing processes and for commissioning new diagnostic pathways for use in primary care.     

Evaluation of the Helicobacter pylori stool antigen (HpSA) test in routine clinical practice--is it patient-friendly?

A new immunoassay has been developed to detect the presence of Helicobacter pylori antigens in stool specimens. The aim of our study was to assess the accuracy and utility of the H. pylori stool antigen (HpSA) test in routine clinical practice. Dyspeptic patients undergoing endoscopy were studied. H. pylori status was defined before treatment by CLOtest and histology, and by 13C urea breath test (UBT) after eradication therapy. A standard universal container was provided for stool collection and the HpSA test was performed by an investigator blind to the results of the other diagnostic tests. Patients also provided a venous blood sample prior to endoscopy for H. pylori serology. Sixty patients (30 M : 30 F: mean age 47 yr) were enrolled in the study. The pretreatment sensitivity, specificity, positive and negative predictive value of the HpSA test were respectively, 93%, 94%, 96%, and 90%. Twenty five patients returned for post treatment 13CUBT, but only 14 (56%) provided a stool sample for analysis. The post treatment sensitivity, specificity, positive and negative predictive value of the HpSA test were respectively, 67%, 100%, 67%, and 92%. The HpSA test was negative in 19% of the patients found positive for anti-H. pylori antibodies on serology testing. All H. pylori antibody-negative patients had a negative HpSA test. Our results suggest that the HpSA test provides accurate pretreatment diagnosis of H. pylori infection but the reliability of the test after treatment is uncertain. A potential problem with the HpSA test appears to be patient reluctance about stool handling and this could prove a significant obstacle to patient compliance and the acceptability of the test in everyday clinical practice.     

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.     

Eradication of Helicobacter pylori in clinical situations

Helicobacter pylori is prevalent worldwide, especially in developing countries, and is associated with several upper gastrointestinal diseases. Since it is present in over 90% of duodenal ulcer patients, empirical eradication in these patients is often recommended. In gastric ulcer patients, eradication is indicated only after the infection is confirmed. Testing for H. pylori infection should be carried out in patients with peptic ulcer hemorrhage, because eradication has been shown to reduce recurrent bleeding. Both H. pylori and NSAIDs are risk factors for peptic ulceration, and it is reasonable to screen for and eradicate H. pylori infection in peptic ulcer patients taking NSAIDs. H. pylori is a group I carcinogen for gastric adenocarcinoma, and should be eradicated for the primary prevention of this cancer. Eradication of this organism has been reported to result in regression of early low-grade mucosa-associated lymphoid tissue lymphoma. The role of H. pylori infection in the causation of gastroesophageal reflux and non-ulcer dyspepsia is not clearly established. Several tests are available for the diagnosis of H. pylori infection. These include invasive tests, such as histology, culture and urease test, and non-invasive tests, such as serology, urea breath test and stool antigen test. The choice of test is determined by clinical indication, pretest probability of infection, as well as the availability, cost, sensitivity and specificity of the test. H. pylori eradication therapy using proton pump inhibitor with clarithromycin and amoxycillin for 7 days has a success rate of 85-90%. Improved living standard and sanitation are vital in the control of H. pylori transmission and infection. Future development may include the use of vaccines against H. pylori, and therapies specifically targeting cagA strains of the bacteria.     

Evaluation of the novel Helicobacter pylori ClariRes real-time PCR assay for detection and clarithromycin susceptibility testing of H. pylori in stool specimens from symptomatic children

The aim of the present study was to evaluate the Helicobacter pylori ClariRes assay (Ingenetix, Vienna, Austria) for the detection of H. pylori infection and the simultaneous clarithromycin susceptibility testing of the H. pylori isolates in stool samples from 100 symptomatic children. The results obtained by this novel biprobe real-time PCR method were directly compared with the results obtained from histological examination of gastric biopsy specimens, culturing, the [13C]urea breath test, and a monoclonal antibody-based stool antigen enzyme immunoassay (EIA). Fecal specimens from all 54 children who were shown to be noninfected by "gold standard" tests gave true-negative PCR results (specificity, 100%). Of the remaining 46 individuals with a positive H. pylori status, 29 were found to be positive by real-time PCR (sensitivity, 63%). For these 29 cases, the H. pylori ClariRes assay confirmed all results from phenotypic clarithromycin susceptibility testing by Etest. In summary, this investigation demonstrates that detection of Helicobacter DNA in stool samples by real-time PCR is a difficult task and that this method cannot replace the stool antigen EIA (sensitivity, 95.7%) for the accurate diagnosis of H. pylori infection in children.     

Evaluation of [13C]urea breath test and Helicobacter pylori stool antigen test for diagnosis of H. pylori infection in children from a developing country

The [(13)C]urea breath test ((13)C-UBT) and Helicobacter pylori stool antigen test (HpSA) for the diagnosis of H. pylori infection in children were validated. The sensitivity, specificity, and positive and negative predictive values were 93.8, 99.1, 97.8, and 98.0%, respectively, for the (13)C-UBT and 96.9, 100, 100, and 98.0%, respectively, for HpSA. Both tests are appropriate for diagnosing H. pylori infection in children.     

Evaluation of a novel rapid one-step immunochromatographic assay for detection of monoclonal Helicobacter pylori antigen in stool samples from children

A new rapid one-step immunochromatographic test using monoclonal antibodies for detection of Helicobacter pylori antigen in stool in children was evaluated on coded stool samples from 159 children (mean age, 9.7 +/- 5.0 years; 118 from Munich, 41 from Vienna): 86 children were H. pylori infected defined by positive culture and/or > or =2 other positive tests ([13C]urea breath test, histology, rapid urease test), and 73 children showed concordant negative results. Seventy-nine patients (12.1 +/- 3.8 years; 42 from Munich; 37 from Vienna) were tested 6 to 8 weeks after anti-Helicobacter pylori therapy with urea breath test and stool test. In Munich, all 160 tests (118 pre- and 42 posttreatment) were independently read by two observers. Equivocal results were excluded for calculation of sensitivity and specificity but were considered as false to assess accuracy. The two observers in Munich agreed in 63 out of 65 positive and 89 out of 95 negative results, while eight times (5.0%) they judged the test as equivocal. Pretreatment and posttreatment results for sensitivity were 88.1% (79.2 to 94.1) and 88.9% (51.8 to 99.7), specificity 88.1% (77.8 to 94.1) and 93.9% (85.2 to 98.3), and accuracy 83.5% and 81.5%, respectively. We conclude that the new monoclonal immunochromatographic quick test shows a good interobserver agreement, but equivocal results occur in 5%. Performance is comparable before and after therapy. The test may become a good alternative in children in settings where a [13C]urea breath test or a reliable enzyme immunoassay stool test are not available.     

New evidence for detecting Helicobacter pylori in clinics

A part of diagnostic tests for Helicobacter pylori was approved as National Health Insurance system in Ministry of Health and Welfare Japan on last November 2000. The gold standard for the presence of most infectious diseases is successful culture of the organism. H. pylori is fastidious and time consuming for growth in media. Instead of bacterial culture of H. pylori from biopsy sample, we need to effort to develop rapid methods to identify gene segment of H. pylori and its antibiotic resistance. Even the genetic methods would be developed, circular antigen product of H. pylori must be important for diagnosis of its clinical pathology. Here we listed the available diagnostic tests for histology, bacterial culture, rapid urease test, urea breath testing, and serological testing for H. pylori in Japan.     

Diagnosis of Helicobacter pylori infections

Hardly any other bacterial infection can be diagnosed with a similar variety of non-invasive and invasive tests as infection with H. pylori. Efficacy and specificity of well-proven tests such as urease test in biopsy specimens, histology, culture, and 13C breath test have been uniformly evidenced in numerous studies. Novel tests include molecular microbiological procedures, providing new opportunities for rapid detection of virulence factors and resistance genes, as well as antigen detection in feces. Though some open questions still need to be clarified, the latter test will gain major importance in the future. With the availability of the breath test and antigen detection in stool the need for the use of serological tests has been reduced, all the more so as the majority of the available quick tests have been shown to be of inadequate reliability. Well defined indications for the treatment of H. pylori infections are a major prerequisite for a reasonable use of this diagnostic armory.     

Estimation of prevalence of Helicobacter pylori infection in an asymptomatic elderly population comparing [14C] urea breath test and serology.

A non-invasive serological assay devised in this laboratory had a sensitivity and specificity of 100% as determined by culture and confirmed by histology in a group of 47 patients who had undergone endoscopy. The correlation between serology and the non-invasive [14C] breath test was very good. Only one of 24 culture positive patients was, while all 23 culture negative patients were, breath test negative. In a group of 46 healthy elderly persons, however, significant anomalies between serology and breath test were observed. Only 83% of the breath test negative persons were seronegative, while only 68% of the breath test positive persons were seropositive. These results can be explained in terms of age related atrophic gastritis and immune incompetence, causing reduced colonisation and decreased antibody production, respectively. These investigations suggest that non-invasive tests for H pylori infection may not be reliable in the elderly.     

Sensitivity of a novel stool antigen test for detection of Helicobacter pylori in adult outpatients before and after eradication therapy

We investigated whether a novel monoclonal stool antigen test for detection of Helicobacter pylori performs with the same accuracy as the (13)C-urea breath test (UBT) for adult outpatients in the setting of a private office. The two tests showed identical levels of sensitivity when used to identify H. pylori-infected patients before and after eradication therapy.     

幽门螺杆菌粪便抗原检测方法学评价

目的 评价幽门螺杆菌粪便抗原（ HpSA）检测在诊断患者幽门螺杆菌（Hp）感染中的价值.方法 以胃镜病理学诊断结果为金标准,对328例有消化道症状患者粪便,同时应用酶联免疫吸附实验检测幽门螺杆菌粪便抗原,计算HpSA检测诊断Hp感染的特异性、灵敏度和准确性等性能指标.结果 幽门杆菌粪便抗原酶免疫检测法对Hp感染诊断与金标准相比无统计学差异（P＞0.05）,其敏感性为94.6％、特异性为96.9％、准确性为96.3％、阳性预期值为89.7％、阴性预期值为98.4％.结论 幽门螺杆菌粪便抗原酶免疫检测是一种简便、易行、准确性高、便宜、易重复的非侵入性检测方法.     

Detection of Helicobacter pylori in faeces by culture, PCR and enzyme immunoassay.

Various techniques such as culture, PCR and enzyme immunoassay have been used to detect Helicobacter pylori infection in human faecal specimens. Attempts to culture H. pylori have had limited success as the bacterium exists predominantly in a non-culturable (coccoid) form in the faeces. Several PCR protocols, differing from each other in the choice of genomic targets and primers, have been used to detect H. pylori infection. Substances in faeces that inhibit PCR have been removed by various pre-PCR steps such as filtration through a polypropylene membrane, biochemical separation by column chromatography and isolation of H. pylori with immunomagnetic beads, the former two techniques yielding results with a high degree of sensitivity and specificity. An enzyme immunoassay based on the detection of H. pylori antigen in faeces has become a convenient tool for the pre-treatment diagnosis of the infection. The stool antigen assay is convenient, especially for children, as it involves neither surgery nor the discomfort associated with the urea breath test. However, its applicability in monitoring eradication therapy has been controversial, as the assay can detect dead or partially degraded bacteria long after actual eradication, thus giving false positive results.     

Detection of Helicobacter pylori antigen in stool by enzyme immunoassay

Invasive techniques for diagnosis of Helicobacter pylori (H. pylori) infection require an endoscopic examination which is expensive and inconvenient and may cause complications. Stool cultures for H. pylori or a direct detection of H. pylori antigen in stools by PCR are expensive, tedious, and have a low sensitivity. We recently used an enzyme immunoassay (EIA) to detect H. pylori antigen in stool specimens. A total of 41 patients were seen at Inha University Hospital, Inchon, Korea between September and October 1998. There were 26 men and 15 women who had an average age of 37.6 years which ranged from 5 to 71 years in the present study. All of these patients came to the hospital complaining of an upper abdominal discomfort and were subjected to endoscopy and biopsies. Fifteen had a gastric ulcer, 13 had a duodenal ulcer, 1 had an early gastric cancer, and there were 12 chronic gastritis patients as shown by endoscopy. The biopsy specimens were examined by histology, CLO test, and cultures and these results were used as gold standards. Stool specimens were tested for the H. pylori antigen by EIA. A dual wavelength cut-off of 0.100 that was recommended by the manufacturer gave a good performance (87.1% sensitivity, 100% specificity, 100% positive predictive value, 71.4% negative predictive value, and a 90.2% efficiency). But the adjusted cut-off value using the receiver operating characteristic curve improved the performance of the test (using the cut-off value of 0.024, the sensitivity, specificity, PPV, NPV, and efficiency were 100%, 90.0%, 96.9%, 100%, and 97.6% respectively). Re-evaluation of the cut-off value may be needed for Korean patients. This technique is non-invasive, rapid, easy-to-use, and shows good performance characteristics for diagnosis of H. pylori infections. Therefore, this technique may be a substitute for gastric endoscopy especially in children and some patients who are unable to tolerate an endoscopic examination and it may be substituted for a serologic test in epidemiological research.     

Diagnosis of Helicobacter pylori infection in adults with intellectual disability

Helicobacter pylori infection is common among adults with intellectual disability. The acceptabilities and accuracies of different diagnostic tests in this population are unknown. We aimed to determine (i) patient acceptability and (ii) performance characteristics of serology, fecal-antigen, and urea breath tests among adults with intellectual disability. One hundred sixty-eight such adults underwent H. pylori testing with serology and fecal-antigen tests, and a portion underwent treatment. One year later, the participants were retested with fecal-antigen, serology, and urea breath tests. The numbers of specimens obtained and difficulties in collection reported by caregivers were noted. Test performance characteristics were assessed among participants and 65 of their caregivers, using serology as the reference. All participants provided at least one specimen, despite reported collection difficulties for 23% of fecal and 27% of blood specimens. Only 25% of the participants provided breath specimens; failure to perform this test was associated with lower intellectual ability and higher maladaptive behavior. The sensitivity, specificity, and positive and negative predictive values of the fecal test (baseline and 12 months versus caregivers) were 70 and 63 versus 81, 93 and 95 versus 98, 96 and 92 versus 93, and 53 and 74 versus 93%, respectively; those of the urea breath test (12 months versus caregivers) were 86 versus 100, 88 versus 95, 75 versus 89, and 94 versus 100%, respectively. With assistance, fecal or blood specimens for H. pylori assessment can be provided by most patients with intellectual disability regardless of their level of function or behavior. Only those with greater ability can perform the urea breath test. Using serology as the reference test, the limitations of performance characteristics of the fecal-antigen and urea breath tests are similar to those among a control group of caregivers.     

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 ¹⁴C 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.     

Helicobacter pylori test and medical reimbursement

There are an estimated 60 million people with Helicobacter pylori(H. pylori) infection who occupied 50% of the population of Japan. In Japanese medical reimbursement H. pylori tests were introduced on November 1, 2000 and they are able to use only to patients with gastric and duodenal ulcer. H. pylori tests were composed of rapid urease test, urea breath test, antibody test, bacterial culture and pathologic test. Payment of each test is 700 Yen. Classification and cost of H. pylori tests are shown. Usage of laboratory tests for H. pylori infection is mentioned. Those particular tests are useful to decrease the number of gastric and duodenal ulcer in Japan.     

Detection of Helicobacter pylori antigen in faeces by enzyme immunoassay

The detection of Helicobacter pylori antigen directly in faecal specimens may offer an alternative non-invasive method for determining the presence of H. pylori infection. This study compared the performance of the Premier Platinum HpSA enzyme immunoassay (HpSA) with histology and CLOtest, a rapid urease test. Of 134 patients undergoing upper gastrointestinal endoscopy, 37 (28%) were H. pylori-positive by histology and CLOtest. Using the HpSA test, H. pylori was detected in 35 H. pylori-positive patients (95% sensitivity) and one H. pylori-negative patient (99% specificity). The positive and negative predictive values for HpSA were 97 and 98%, respectively. HpSA is a rapid, easily performed, non-invasive method for detecting H. pylori.