What are the methods for diagnosing and treating Helicobacter pylori (H. pylori) infection?

Diagnosis of Helicobacter pylori Infection

The urea breath test (UBT) and stool antigen test are the recommended non-invasive diagnostic methods for H. pylori infection, with UBT demonstrating sensitivity of 94-97% and specificity of 95%, and stool antigen test showing sensitivity and specificity of approximately 93%. 1, 2

Non-Invasive Diagnostic Methods

Preferred First-Line Tests

• The urea breath test (UBT) is considered the most accurate non-invasive test for H. pylori, detecting active infection by measuring urease activity 1, 2
• Laboratory-based validated monoclonal stool antigen test directly detects H. pylori bacterial antigens in stool specimens with comparable accuracy to UBT 1, 2
• Both UBT and stool antigen tests detect active infection rather than just past exposure, making them valuable for both initial diagnosis and confirmation of eradication 1

Serological Testing Limitations

• Serological tests detect anti-H. pylori IgG antibodies but cannot distinguish between active infection and previous exposure 1
• The overall accuracy of commercial ELISA serology tests averages only 78% (range 68-82%), which is inadequate for clinical use 1
• Serology tests should not be used to confirm eradication after treatment as antibodies remain elevated after H. pylori elimination 1

Invasive Diagnostic Methods (Requiring Endoscopy)

• Histological examination requires at least two biopsy samples from the antrum and body for improved sensitivity 2
• Rapid urease test (RUT) has pre-treatment sensitivity of 80-95% with specificity of 95-100%, requiring approximately 10^4 organisms for a positive result 3, 2
• Culture provides definitive proof of infection and allows for antimicrobial susceptibility testing, particularly valuable after treatment failure when antimicrobial resistance is suspected 2

Testing Algorithm

Initial Diagnosis in Primary Care Setting

• For young (<50 years) dyspeptic patients without alarm symptoms: Use UBT or laboratory-based monoclonal stool antigen test 3, 1
• For patients with alarm symptoms (bleeding, weight loss, dysphagia, palpable mass) or age ≥50 years with new-onset dyspepsia: Perform endoscopy with invasive testing 1

Confirmation of Eradication

• Testing should be performed no earlier than 4 weeks after completion of treatment 1
• Use UBT or stool antigen test for confirmation, never serology 1

Important Considerations and Pitfalls

• Proton pump inhibitors should be stopped for at least 2 weeks before testing by culture, histology, rapid urease test, UBT, or stool test to avoid false-negative results 1, 2
• Antibiotics should be discontinued at least 4 weeks before testing 2
• Rapid in-office serological tests have limited accuracy and should be avoided 1
• For patients who have failed eradication therapy, especially when antimicrobial resistance is suspected, endoscopy with culture and susceptibility testing is recommended 1, 2

Treatment Approach

• For H. pylori eradication, combination therapy is required, typically including a proton pump inhibitor with antibiotics 4, 5, 6
• Triple therapy with amoxicillin, clarithromycin, and a proton pump inhibitor (lansoprazole or omeprazole) is a standard first-line regimen in areas with low clarithromycin resistance (<15%) 4, 5, 6, 7
• Dual therapy with amoxicillin and lansoprazole is indicated for patients allergic or intolerant to clarithromycin or when clarithromycin resistance is suspected 4
• Treatment duration of 14 days is generally recommended for optimal eradication rates 7