How to Test for H. pylori
For non-invasive testing, use the urea breath test (UBT) or stool antigen test (SAT) as first-line methods, as they accurately detect active infection with high sensitivity and specificity comparable to invasive biopsy-based tests 1, 2.
Testing Algorithm Based on Clinical Context
For Initial Diagnosis (Test-and-Treat Strategy)
Non-invasive tests are preferred:
- Urea Breath Test (UBT): Most accurate non-invasive method for detecting active infection
- Stool Antigen Test (SAT): Equally accurate alternative to UBT, particularly useful in children and mass screening 2, 3
Critical caveat: Stop PPIs for 2 weeks before testing with UBT, SAT, or any biopsy-based test (culture, histology, rapid urease test), as PPIs cause 10-40% false-negative results by decreasing bacterial load 1. If stopping PPIs is not possible, use validated IgG serology instead 1.
For Patients Undergoing Endoscopy
Invasive biopsy-based tests can be performed:
- Rapid Urease Test (RUT): Take biopsies from the greater curvature of both antrum AND corpus for optimal accuracy (κ=0.70) 4. Single-site biopsy from corpus greater curvature alone shows sensitivity of 0.89 4.
- Histology: Can detect H. pylori even with low bacterial load by identifying surrogate features (polymorphonuclear cells) 1
- Culture with susceptibility testing: Essential in high clarithromycin resistance regions before first-line treatment, and recommended before second-line treatment 1
Special Circumstances
If patient is on PPIs and cannot stop them:
- Use validated IgG serology (Grade B recommendation) 1
- Serology remains positive for months after infection and is unaffected by PPI use or low bacterial load 1
- Major limitation: Cannot differentiate current from past infection 2
For antibiotic resistance detection:
- Molecular tests (PCR) can detect H. pylori and clarithromycin/fluoroquinolone resistance directly from gastric biopsies when standard culture is unavailable 1
- Gastric fluid qPCR shows promise with better sensitivity than gastric mucosa qPCR for both infection and resistance detection 5
Key Pitfalls to Avoid
- Do not use serology for test-of-cure: Antibodies persist long after eradication 1
- Do not test while on PPIs (except serology): Results in high false-negative rates across all active infection tests 1
- Do not rely on single antral biopsy for RUT: Bacterial distribution favors greater curvatures; two-site approach (antrum + corpus greater curvatures) maximizes accuracy 4
- H2 blockers have minimal effect: No need to stop them before testing if using citric acid 1
Summary of Test Selection
- Active infection diagnosis without endoscopy: UBT or SAT (stop PPIs 2 weeks prior)
- Patient on PPIs who cannot stop: Validated IgG serology
- During endoscopy: RUT from antrum + corpus greater curvatures, plus culture for resistance testing in appropriate scenarios
- Post-treatment confirmation: UBT or SAT (never serology)
No single test serves as the universal gold standard 6; selection depends on clinical context, PPI use, endoscopy availability, and need for resistance profiling 1, 2.