Fresh faecal sample, a minimum of 2g.
As of 12/5/25, Vetting restrictions are in place for requests on paediatric samples ? see approval criteria and related information under "Notes on samples for children <16 years of age" below
Principle: Sandwich chemiluminescent immunoassay
Assay: Diasorin
Analyser: Liaison
Uncertainty of Measurement:
Faecal H.pylori antigen is currently reported qualitatively. In addition to analytical variation in the method itself, there is also variation due to stool sampling variability, and variation in antigen excretion from day to day. Further discussions can be directed to the on call Clinical Microbiologist via LabPlus Lablink.
Clinical Use
- Diagnosis of H. pylori infection
- Therapeutic monitoring during treatment of H. pylori infection
- Proof of H. pylori eradication in patients following treatment for H. pylori infection
Background
H. pylori is a micro-aerophilic, spirally-shaped, gram-negative bacterium with unipolar flagella, requiring carbon dioxide and a rich growth media. It lives on the human gastric mucosa, and colonization stops abruptly where gastric mucosa ends. H . pylori causes chronic gastritis, duodenal and stomach ulcers, and is associated with an increased risk of gastric cancer. Transmission is by ingestion, such as via the faecal-oral route. Once colonization in the stomach is established, H. pylori will usually persist indefinitely unless antimicrobial therapy is given. Its elimination allows healing of ulcers without recurrence.
H. pylori colonizes the stomach by the use of its flagella to burrow through the mucus to reach the stomach epithelial cell layer. In addition, urease, produced by H. pylori , is important for its survival in the harsh acidic environment in the stomach as urease is able to degrade urea into carbon dioxide and ammonia, which helps in neutralizing the gastric acid.
Diagnositic Interpretation
A number of methods can be used to diagnose H. pylori infection including:
- Invasive tests: Urease test on biopsy of stomach or duodenum, histology and culture
- Non-invasive tests: Carbon-13 urea breath test, serology and faecal stool antigen testing
The H. pylori faecal antigen test is a chemiluminescent immunoassay (CLIA) with monoclonal antibodies for detection of H. pylori stool antigen. The test can also be used for the therapeutic monitoring and documentation of eradication of H. pylori infection in patients following treatment. The result of the test may be used in conjunction with other laboratory and clinical data to help in making a management decision for the patient.
The test requires the use of fresh faecal sample . The result for the assay can be one of the following:
| Results | Interpretation |
| Negative |
Indicates absence of H. pylori stool antigen, (or the antigen level is below that can be detected by the assay) |
| Equivocal |
For samples with equivocal results on initial testing, a new specimen should be collected |
| Positive |
Indicates the presence of detectable H. pylori stool antigen |
The faecal antigen test has been reported to have a sensitivty of 94-95%, specificity of 94-97%, and positive predictive value of 84%. Sensitivity and specificity of the test are comparable to carbon-13 urea breath testing for H. pylori diagnosis.
False-negative results can occur if the patient has used antimicrobials in the last 4 weeks, or used proton pump inhibitors/bismuth in the last 2 weeks prior to testing. Accuracy of the test can also be reduced if the patient had upper GI bleeding or if the faecal specimen is unformed or watery consistency.
References
- Kit insert
- BPAC 2014
- Mayo Clinic: Mayo Medical Laboratories Online
- UpToDate 2015
|
| Notes on sample for children <16 years of age |
For further information, contact the Microbiology Department via Lablink or the Clinical Microbiologist:
Dr Sally Roberts
, Microbiologist:
ext 22705
Cellphone
021 674 140
Dr Sharmini Muttaiyah
, Microbiologist:
ext 22700
Cellphone
021 615 892
Dr Mary de Almeida
, Microbiologist:
ext 22700
Cellphone
021 170 9117
LabTests Auckland only - samples can be sent refrigerated and will be frozen on arrival at LabPlus (the exception being samples from Northland which should be sent frozen)
All other laboratories - send frozen to ensure the stability of the sample