What is the H. Pylori Stool Antigen Test?


Written by: CDHF

Updated: November 16th, 2022

H. pylori stool antigen test: A non-invasive test for diagnosing H.pylori infection

What is H. Pylori?

H. Pylori (Helicobacter pylori) is a bacteria that can bring about infection within the stomach or duodenum (the first part of the small intestine) causing peptic ulcer disease, as well as gastritis. The presence of the bacteria mostly occurs in children – furthermore, a mere 20% of people with the infection will actually exhibit symptoms.

What are the potential consequences of H. Pylori infection?

H. Pylori infection can lead to ulcers, gastritis (inflammation and irritation of the stomach lining), and in very rare cases (mainly long-term) stomach cancer.

It is worth noting that nearly 50 to 75% of the world’s population have the presence of the H. Pylori bacteria. More common in developing countries, infection is most likely to occur in children who live in crowded conditions, as well as areas with poor sanitation.

H. Pylori can also spread from person to person – the bacteria can be found in saliva, the plaque on teeth, as well as in your stool. Kissing can transmit the infection, as well as improper hand-washing before interactions.

Why should I test for H. Pylori?

The consequences noted above are important for health considerations. Further, testing is key as H pylori infection is curable and the bacteria can be eradicated (testing can confirm eradication).

Are there symptoms for those with an H. Pylori infection?

Most people do not have signs or symptoms – some people are born more resistant to the harmful effects of the bacteria (the medical community is still unclear on why this is. When symptoms DO occur, they may include:

It is extremely important to make an appointment with your doctor if you have severe or persistent abdominal pain, difficulty swallowing, bloody/black tarry stools, or bloody/black vomit.

How do you test for H. Pylori infection?

Testing for the infection can essentially be split into two categories – invasive and non-invasive testing. Invasive testing usually involves an endoscopy. Endoscopy is a nonsurgical procedure used to examine a person’s digestive tract. Using an endoscope, a flexible tube with a light and camera attached to it, your doctor can view pictures of your digestive tract on a color TV monitor. As with any invasive procedure, it may come with some discomfort and risk.

Non-invasive tests bring a few more options – the stool antigen test, serological testing, and a urea breath test.

Stool Antigen Test

Unlike other tests normally used for the diagnosis of the infection, the stool antigen test detects the antigen of the bacterium, as opposed to the antibodies developed as a result. A stool antigen test checks to see if substances that trigger the immune system to fight an H. Pylori infection (H. Pylori antigens) are present in the stool. It is capable of diagnosing an ongoing infection, whereas the serological testing merely diagnoses contact with the bacterium (this can be current or within a whole lifetime).

The stool antigen test has many positive aspects: it is non-invasive, quick, has good sensitivity, specificity and reliability (presents good replication standards). This test can be used both for diagnosis of the infection and for monitoring therapy effectiveness, already four weeks after the end of treatment. Its low cost, easy use and the possibility to collect samples and perform the test at home have increasingly widespread the use of this method.

Serological Testing

Serological testing is a non-invasive test that detects antibodies to H pylori. Most people infected with H. Pylori generally present very specific circulating antibodies, detectable through this type of testing. However, the serological testing cannot distinguish between a previous versus an active infection. Moreover, it cannot confirm the bacteria eradication.

Urea Breath Test

This test is widely available, with a high sensitivity and specificity for diagnosing H. Pylori infection. A urea breath test checks to see if the H. pylori bacteria is present in the stomach. During the test, a patient will be asked to exhale into a test tube, drink a solution, and then exhale into another tube. If the amount of carbon dioxide in your second sample is higher than the amount in your first sample, you have a positive test for the presence of H. pylori. It is a safe and non-invasive test.

In conclusion, there is no ‘gold standard’ for the diagnosis of H. Pylori infection, but the stool antigen test is considered to be a front runner.

Watch our CDHF Talk with Dr. Karen Kroeker from the University of Alberta who explains the important role stool tests play in diagnosis and treatment of digestive disorders.




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