Stool test for Helicobacter pylori

Approach to Helicobacter pylori infection in geriatric population

The prevalence of Helicobacter pylori (H. pylori) infection and its complications increase with age. The majority of infected individuals remain asymptomatic throughout the life but 10%-20% develops peptic ulcer disease and 1% gastric malignancies. The incidence of ulcers and their complications are more common in the older population resulting in higher hospitalization and mortality rates. The increased use of medications causing gastric mucosal damage and the decreased secretion of protective prostaglandins in elderly are major factors increasing gastric mucosal sensitivity to the destructive effects of H. pylori. Due to higher prevalence of gastrointestinal (GI) malignancies, upper GI endoscopy is mostly preferred in elderly for the diagnosis of infection. Therefore, “endoscopy and treat” strategy may be more appropriate instead of “test and treat” strategy for dyspeptic patients in older age. Urea breath test and stool antigen test can be used for control of eradication, except for special cases requiring follow-up with endoscopy. The indications for treatment and suggested eradication regimens are similar with other age groups; however, the eradication failure may be a more significant problem due to high antibiotic resistance and low compliance rate in elderly. Multidrug usage and drug interactions should always be considered before starting the treatment. This paper reviews briefly the epidemiology, diagnosis, disease manifestations, and treatment options of H. pylori in the geriatric population.

Helicobacter pylori detection and antimicrobial susceptibility testing

The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Stool antigen tests in the diagnosis of Helicobacter pylori infection before and after eradication therapy

AIM

To evaluate two enzyme immunoassay-based stool antigen tests, Premier Platinum HpSA and Amplified IDEIA HpStAR, and one rapid test, ImmunoCard STAT! HpSA, in the primary diagnosis of Helicobacter pylori (H pylori) infection and after eradication therapy.

METHODS

Altogether 1 574 adult subjects were screened with a whole-blood H pylori antibody test and positive results were confirmed with locally validated serology and (13)C-urea breath test. All 185 subjects, confirmed to be H pylori positive, and 97 H pylori-negative individuals, randomly selected from the screened study population and with negative results in serology and UBT, were enrolled. After eradication therapy the results of 182 subjects were assessed.

RESULTS

At baseline, the sensitivity of HpSA and HpStAR was 91.9% and 96.2%, respectively, and specificity was 95.9% for both tests. ImmunoCard had sensitivity of 93.0% but specificity of only 88.7%. After eradication therapy, HpSA and HpStAR had sensitivity of 81.3% and 100%, and specificity of 97.0% and 97.6%, respectively. ImmunoCard had sensitivity of 93.8% and specificity of 97.0%. HpSA, HpStAR, and ImmunoCard had PPV 77%, 80%, and 75%, and NPV 98%, 100%, and 99%, respectively.

CONCLUSION

In primary diagnosis, the EIA-based tests performed well. After eradication therapy, negative results were highly accurate for all the three tests. HpStAR had the best overall performance.

Evaluation of Helicobacter pylori with a stool antigen assay in frail, elderly patients

OBJECTIVE

Helicobacter pylori infection has not been studied thoroughly in elderly patients. The aim of this study was to evaluate the reliability of stool antigen assay (HpSA) in the assessment of H. pylori infection in hospitalized, frail, elderly patients.

MATERIALS AND METHODS

The study population consisted of 85 consecutively recruited elderly patients (> or =65 years old) hospitalized between May 1999 and December 2001 with diagnostic indications for upper gastrointestinal endoscopy. Twenty-nine subjects had been receiving treatment with proton-pump inhibitors (PPIs), such as omeprazole (10-20 mg/day) for 2-15 days, and 56 were not receiving treatment. HpSA was evaluated versus UBT (urea breath test), serology and histology: patients with at least two positive results out of the latter three tests were considered positive for H. pylori infection, while patients with at least two negative tests out of three were considered negative.

RESULTS

The sensitivity and specificity of HpSA in the 56 untreated patients were, respectively, 76% (true positives TP = 22; false negatives FN = 7) and 93% (true negatives TN = 25; false positives FP = 2). The sensitivity and specificity of HpSA in the 29 patients on PPI treatment were, respectively, 82% (TP = 9; FN = 2) and 83% (TN = 15; FP = 3).

CONCLUSIONS

HpSA is an accurate, non-invasive and easy method for diagnosing H. pylori infection in elderly patients.

Helicobacter pylori infection diagnosis in hospitalised elderly patients: the stool antigen test (HpSA) in comparison with other methods

BACKGROUND AND AIMS

Helicobacter pylori (Hp) infection prevalence increases with age. In elderly patients, who often do not collaborate and who are affected by multiple pathologies, worldwide-recognised invasive and non-invasive methods (histology and Urea Breath Test) are not easy to apply. A new test based on the detection of Hp antigens in the stool (HpSA test) is now available. The aim of our study was to evaluate the sensitivity and specificity of the HpSA test, and the interference of drugs (acid suppression, antibiotics) on test performance.

METHODS

Hp infection was detected by UBT, HpSA and histology in 122 hospitalised elderly subjects, divided into two groups according to therapy in the last month. Subjects were classified as being Hp-positive if two test results (histology and UBT) were positive, and Hp-negative if the same two test results were negative.

RESULTS

The sensitivity and specificity of the HpSA test compared with two tests (histology and UBT) were respectively 76 and 95%. In the group of patients who had not received drugs, the sensitivity and specificity of the HpSA test were respectively 76 and 96%. Instead, in the group of patients who had received pharmacological therapy, sensitivity and specificity values were respectively 67 and 100%. HpSA-positive patients had received acid suppression for 9.2 +/- 8.9 days, and false-negative patients for 27.2 +/- 9.9 days.

CONCLUSIONS

The HpSA test is simple, inexpensive, and non-invasive for Hp detection, especially in elderly subjects with no compliance. It is influenced only after several days by therapy common in the elderly.

Stool antigen test for diagnosis of Helicobacter pylori infection in children with symptomatic disease: a prospective study

OBJECTIVE

Noninvasive tests for the diagnosis of Helicobacter pylori (Hp) infection in children are limited by low accuracy rates and lack of validation. Existing studies indicate that the stool antigen test (HpSA) has an acceptable level of accuracy for the diagnosis of Hp infection in adults but not children. The aim of this study was to evaluate the accuracy of the HpSA test for the detection of Hp infection in U.S. children.

METHODS

Children requiring upper endoscopic procedures were prospectively recruited from two pediatric gastroenterology clinics. Stool samples were collected from each participant before endoscopy. The presence of Hp infection was determined by positive histologic findings and positive rapid urease test (RUT). The presence of Hp organisms in stool was determined by an enzyme-linked immunosorbent assay using a commercially available polyclonal antibody kit (Meridian Diagnostics, Cincinnati, OH, U.S.A.). Results of the stool antigen test were compared with histology findings and RUT results.

RESULTS

One hundred twenty-one children (mean age, 10.1 +/- 3.7 years) participated, of whom 9 (7.4%) had Hp infection. Histologic findings and RUT results were concordant in 95% of the children. Per study protocol, HpSA had a sensitivity, specificity, positive and negative predictive value, and accuracy rate of 67%, 99%, 86%, 97%, and 96.5%, respectively.

CONCLUSION

HpSA, a polyclonal antibody test, had a low sensitivity for infection in children in the United States and at present cannot replace histologic findings as the gold standard for the diagnosis of Hp infection in the pediatric population.

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.

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.