What are the recommended diagnostic tests and treatment options for Helicobacter pylori (H. pylori) infection?

Diagnostic Tests for H. pylori

For initial diagnosis in patients under 50 years without alarm symptoms, use the urea breath test (UBT) or laboratory-based monoclonal stool antigen test as first-line non-invasive tests, both achieving approximately 93-97% accuracy. 1, 2

Non-Invasive Testing Approach

Preferred First-Line Tests

• Urea Breath Test (UBT) demonstrates the highest accuracy among non-invasive methods with sensitivity of 94.7-97% and specificity of 95-95.7%, detecting active infection by measuring urease activity 1, 2

• Laboratory-based monoclonal stool antigen test directly detects H. pylori bacterial antigens with sensitivity and specificity of approximately 93%, comparable to UBT 1, 3, 2

• Both tests detect active infection rather than past exposure, making them valuable for initial diagnosis and confirmation of eradication 1, 3

When Serology May Be Considered (Limited Role)

• Validated IgG serology should only be used in specific circumstances: recent antimicrobial or PPI use, ulcer bleeding, atrophic gastritis, or gastric malignancies where other tests may be falsely negative 4, 1

• Critical limitation: Serology cannot distinguish between active infection and past exposure, with antibodies persisting for months to years after eradication, resulting in an average accuracy of only 78% 1

• Never use serology for confirmation of eradication as antibodies remain elevated long after bacterial elimination 1, 2

Invasive Testing During Endoscopy

When to Proceed Directly to Endoscopy

• Patients ≥50 years with new-onset dyspepsia due to increased malignancy risk 1, 3
• Any patient with alarm symptoms: bleeding, weight loss, dysphagia, palpable mass, anemia, or malabsorption 1, 3
• After treatment failure when culture and antimicrobial susceptibility testing are needed 4, 1

Available Invasive Tests

• Rapid urease test (RUT): Pre-treatment sensitivity 80-95%, specificity 95-100%, provides quick results during endoscopy 2

• Histology: Requires at least two biopsy samples from antrum and body for improved sensitivity, allows visualization of bacteria and mucosal damage 4, 2

• Culture with susceptibility testing: Provides definitive proof and antimicrobial resistance patterns, particularly valuable in regions with high clarithromycin resistance (>15-20%) or after treatment failure 4

• Molecular tests (PCR): Can detect H. pylori and clarithromycin/fluoroquinolone resistance directly from biopsies when culture is not possible 4

Critical Medication Washout Periods

To Avoid False-Negative Results

• Stop PPIs for at least 2 weeks before testing by culture, histology, RUT, UBT, or stool test, as PPIs cause 10-40% false-negative rates by reducing bacterial load 4, 1

• Stop antibiotics and bismuth for at least 4 weeks before testing 1, 2

• H2-receptor antagonists may cause some false-negatives but to a lesser extent; stopping is not mandatory if using citric acid with UBT 4, 5

• Exception: Serology is the only test unaffected by these medications 4

Confirmation of Eradication

• Timing: Test no earlier than 4 weeks after completing treatment 1, 2

• Recommended tests: UBT or laboratory-based monoclonal stool antigen test only—never serology 1, 2

• Post-treatment stool test performance: Sensitivity 91.6%, specificity 98.4% for monoclonal antibody-based tests 1

Common Pitfalls to Avoid

• Avoid rapid in-office immunochromatographic stool tests: These have significantly lower accuracy (sensitivity 68.9-86.7%, specificity 87-92.6%) compared to laboratory-based monoclonal tests 1, 6

• Avoid rapid in-office serological tests: Limited accuracy and should not be used 1

• Do not test patients currently on PPIs unless using serology or after appropriate washout period 4

• Do not use panels of IgG, IgA, and IgM tests: Provides no added benefit over validated IgG tests alone 1

Algorithm for Test Selection

For patients <50 years without alarm symptoms:

1. First choice: UBT or laboratory-based monoclonal stool antigen test 1, 3, 2
2. If recently used antibiotics or PPIs: Either wait 2-4 weeks after stopping medications, or use validated IgG serology 4, 1

For patients ≥50 years or with alarm symptoms:

1. Proceed directly to endoscopy with RUT, histology, or culture 1, 3
2. Consider culture with susceptibility testing in high clarithromycin resistance areas or after treatment failure 4

For confirmation of eradication:

1. Wait at least 4 weeks after completing treatment 1, 2
2. Use UBT or laboratory-based monoclonal stool antigen test only 1, 2