From the Guidelines
The stool antigen test for H. pylori is a reliable and recommended non-invasive diagnostic method to detect active Helicobacter pylori infection, with high sensitivity and specificity, especially when using a validated laboratory-based monoclonal test. This test is useful for both initial diagnosis and to confirm eradication after treatment, as stated in the Maastricht IV/Florence Consensus Report 1. The test involves analyzing a small stool sample for specific antigens produced by the bacteria, and patients should avoid taking certain medications such as proton pump inhibitors and antibiotics before the test to prevent false negative results.
Some key points to consider when using the stool antigen test include:
- The test has high accuracy, with sensitivity and specificity rates comparable to the UBT, especially when using a validated laboratory-based monoclonal test 1.
- Patients should wait at least 4 weeks after completing treatment before retesting to confirm eradication.
- The test is more accurate than blood antibody tests, which cannot distinguish between current and past infections.
- The use of a validated laboratory-based monoclonal test is recommended over rapid in-office tests, which have limited accuracy 1.
In terms of treatment, if the test is positive, triple therapy for 14 days is typically recommended, consisting of a proton pump inhibitor plus two antibiotics, such as amoxicillin and clarithromycin or metronidazole 1. It is essential to follow the recommended treatment guidelines and to retest after treatment to confirm eradication, as stated in the management of H. pylori infection--the Maastricht IV/Florence Consensus Report 1.
From the Research
Stool Antigen Test for H. pylori
- The stool antigen test is a non-invasive diagnostic tool for detecting H. pylori infection 2, 3, 4.
- A study comparing a monoclonal with a polyclonal antibody-based enzyme immunoassay stool test found that the monoclonal stool antigen test had a sensitivity of 91.6% and specificity of 98.4% 2.
- A meta-analysis of diagnostic test accuracy found that conventional stool antigen tests had superior sensitivity and specificity compared to rapid tests, with a sensitivity of 92.19% and specificity of 92.93% 3.
- The stool antigen test can be used to assess the eradication of H. pylori infection after treatment, with a study finding that high-dose dual therapy with esomeprazole and amoxicillin had an eradication rate of 91.8% as confirmed by the H. pylori stool antigen test 5.
Diagnostic Accuracy
- The diagnostic accuracy of stool antigen tests can vary depending on the type of test and antibodies used, with monoclonal antibodies showing higher sensitivity and specificity in some studies 2, 3.
- The use of stool antigen tests in combination with other diagnostic tools, such as urea breath tests, can improve the accuracy of H. pylori diagnosis 4.
- Studies have shown that stool antigen tests can be a reliable and convenient option for diagnosing H. pylori infection, especially in adults 3, 4.
Clinical Applications
- Stool antigen tests can be used as a first-line diagnostic tool for H. pylori infection, especially in cases where endoscopy is not feasible or available 4.
- The tests can also be used to monitor the effectiveness of treatment and confirm eradication of the infection 2, 5.
- The convenience and non-invasiveness of stool antigen tests make them a valuable tool in clinical practice, particularly in primary care settings 3, 4.