From the Guidelines
To diagnose H. pylori infection, the urea breath test (UBT) or stool antigen test is recommended as the initial noninvasive test, as they are highly accurate and reliable, according to the most recent evidence 1. When choosing a diagnostic test for H. pylori, it is essential to consider the clinical indication, local availability, and costs of the different tests, as well as patient preferences.
- The UBT and stool antigen test are susceptible to false negative results if the patient has recently taken antibiotics, bismuth, or proton pump inhibitors (PPIs), so it is recommended to stop these medications for at least 2 weeks before testing 1.
- Serologic tests, such as those for anti-H. pylori IgG antibodies, are not recommended for initial diagnosis due to their low specificity and sensitivity, and the fact that they can remain positive long after the infection has been eradicated 1.
- Endoscopy with biopsy may be necessary in certain cases, such as when invasive testing is required or when the patient has failed eradication therapy and needs culture and antimicrobial sensitivity testing 1.
- The choice of test should be based on the clinical circumstances, the likelihood ratio of positive and negative tests, the cost-effectiveness of the testing strategy, and the availability of the tests 1.
- It is crucial to confirm the presence of an active infection before starting treatment, especially if serology is used, to avoid unnecessary treatment and to ensure the best possible outcome for the patient 1.
From the Research
H pylori Testing
- The "test-and-treat" strategy is the recommended approach for managing H. pylori infection, with the choice of testing method based on patient age, symptoms, and medication use, as well as test reliability and cost 2.
- Invasive tests for H. pylori diagnosis include biopsy urease test and histology, while noninvasive tests include urea breath test and stool antigen testing 3.
- Proton pump inhibitor therapy can lead to false-negative H. pylori test results, and treatment should be stopped for 1-2 weeks prior to testing if possible 3.
Stool Antigen Testing
- Stool antigen testing is a simple, accurate, and non-invasive test for detecting H. pylori infection, with a sensitivity of 95.0% and specificity of 100% 4.
- The use of domestically produced kits for stool antigen testing may be less likely to yield false-negative results, even when patients are taking proton pump inhibitors 5.
- Bioluminescent enzyme immunoassay is a recommended method for stool antigen testing due to its high sensitivity 5.
Comparison of Testing Methods
- The urea breath test and stool antigen test can give discordant or indeterminate results in nearly 8% of patients after treatment, with the stool antigen test being less accurate than the urea breath test 6.
- The accuracy of the stool antigen test can be affected by the presence of coccoid forms of H. pylori, but this does not cause false positive results 6.