What is the diagnostic test for Helicobacter pylori (H. pylori) infection?

From the Guidelines

All patients with bleeding peptic ulcers should undergo H. pylori testing to confirm the presence of the infection and guide treatment decisions. The most recent and highest quality study, published in 2020 by Tarasconi et al. in the World Journal of Emergency Surgery 1, recommends H. pylori testing for all patients with bleeding peptic ulcers. Several testing options are available, including non-invasive methods like the urea breath test (UBT) and stool antigen testing, which have high sensitivity and specificity (>90%) 1.

Testing Options

• Urea breath test (UBT): detects H. pylori infection by measuring the amount of carbon dioxide produced by the bacteria in the breath
• Stool antigen test: detects H. pylori proteins in stool samples
• Blood antibody test: less useful for active infection confirmation as it remains positive even after successful treatment

Recommendations

• Patients should avoid antibiotics for 4 weeks and proton pump inhibitors for 1-2 weeks before testing to prevent false negatives
• After treatment, confirmation of eradication is typically done 4-8 weeks later using the breath or stool test
• Testing is important because H. pylori infection increases the risk of peptic ulcers and gastric cancer, and successful eradication significantly reduces these risks

Clinical Considerations

• The choice of test should depend 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
• Invasive studies, such as endoscopy, may be warranted in patients with alarm symptoms or older patients with new-onset dyspepsia 1

From the Research

H pylori Test Overview

• The "test-and-treat" strategy is the recommended approach for managing H. pylori infection, with the choice of testing method based on patient age, presenting symptoms, and medication use, as well as test reliability, availability, and cost 2.
• Non-invasive tests for H. pylori infection include serology, urea breath test, urine/blood test, and detection of H. pylori antigen in stool specimen, with some tests detecting active infection and others indicating exposure to H. pylori 3, 4.

Types of H pylori Tests

• Invasive tests that accurately identify current infection include the biopsy urease test and histology 5.
• Non-invasive tests that detect active infection include the urea breath test and stool antigen testing, while serology and urine/blood tests are markers of exposure to H. pylori but do not indicate if active infection is ongoing 5, 3, 4.
• Molecular tests based on Real-Time Polymerase Chain Reaction (RT-PCR) in feces can also be used to screen for H. pylori infection and assess Clarithromycin resistance 6.

Test Characteristics and Recommendations

• The urea breath test and stool antigen test have high sensitivity and specificity for detecting H. pylori infection, with the molecular test based on RT-PCR in feces showing 85.71% sensitivity and 100% specificity 6.
• 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 5.
• The choice of an appropriate test depends on the pre-test probability of infection, the characteristics of the test being used, and the cost-effectiveness of the test 3, 4.