What is the recommended approach for investigating Helicobacter pylori (H pylori) infection?

Recommended Approach for Investigating Helicobacter pylori Infection

The urea breath test (UBT) and stool antigen test are the preferred non-invasive diagnostic methods for detecting active H. pylori infection, with both showing excellent sensitivity and specificity of approximately 93-95%. 1, 2

Diagnostic Strategy Based on Patient Age and Symptoms

For Young Patients (<50 years) Without Alarm Symptoms:

• Implement a "test and treat" strategy using non-invasive tests to reduce unnecessary endoscopies 3, 1
• Choose between:
  • Urea Breath Test (UBT) - considered the most accurate non-invasive test with sensitivity of 94.7% and specificity of 95.7% 3, 1
  • Stool Antigen Test - comparable accuracy with sensitivity and specificity of approximately 93% 3, 2

For Patients with Alarm Symptoms or Age ≥50 Years:

• Proceed directly to endoscopy with invasive testing due to increased risk of malignancy 3, 1
• During endoscopy, obtain biopsies for:
  • Rapid urease test - provides quick results during the procedure 1
  • Histology - allows visualization of bacteria and assessment of mucosal damage 1
  • Culture - especially valuable for antimicrobial susceptibility testing after treatment failure 1

Advantages and Limitations of Diagnostic Tests

Non-Invasive Tests:

• Urea Breath Test (UBT):

  • Detects active infection rather than past exposure 1
  • Excellent accuracy with sensitivity 94.7-97% and specificity 95-95.7% 3, 1
  • Available in 13C (non-radioactive) and 14C (radioactive) forms 3
  • False negatives can occur with recent PPI use (discontinue 2 weeks before testing) 3, 1

• Stool Antigen Test:

  • Directly detects H. pylori bacterial antigens in stool specimens 2
  • Comparable accuracy to UBT with sensitivity and specificity around 93% 3, 2
  • More practical than invasive methods, avoiding discomfort and complications 2
  • Laboratory-based validated monoclonal antibody tests are preferred over polyclonal tests 1

• Serologic Tests:

  • Not recommended as primary diagnostic method due to inability to distinguish between active infection and past exposure 1
  • Cannot be used to confirm eradication as antibodies remain elevated after treatment 1
  • Limited accuracy (average 78%, range 68-82%) 1
  • May be useful only in specific situations (large epidemiologic surveys, when other tests might be falsely negative) 1

Invasive Tests (Requiring Endoscopy):

• Rapid Urease Test:

  • Less sensitive but specific 4
  • Provides quick results during endoscopy 4
  • May be followed by histological testing if negative 4

• Histology:

  • Allows assessment of gastric inflammatory mucosal lesions 4
  • Immunohistochemistry with H. pylori specific antibodies is most accurate 3

• Culture:

  • Helpful for determining antimicrobial resistance patterns 4
  • Essential for planning second-line treatment after eradication failure 4

• PCR:

  • Can detect H. pylori and antibiotic resistance directly from biopsies 1
  • Particularly useful for detecting clarithromycin resistance 5

Important Considerations for Testing

• Proton pump inhibitors (PPIs) should be discontinued at least 2 weeks before testing to avoid false-negative results 1
• Antibiotics and bismuth compounds should be stopped at least 4 weeks before testing 1
• For confirmation of eradication, testing should be performed no earlier than 4 weeks after completion of treatment 1, 6
• The UBT or stool antigen test are recommended for determining the success of eradication treatment 1

Special Populations and Indications for Testing

• Primary indications for H. pylori testing include:

  • Active peptic ulcer disease or history of peptic ulcer disease 1
  • Gastric MALT lymphoma 1
  • Patients requiring long-term PPI therapy (>1 year) 1
  • Patients with atrophic gastritis or intestinal metaplasia 1
  • High-risk populations (e.g., first-generation immigrants from high-prevalence countries) 3

• Consider testing family members of infected individuals to prevent person-to-person transmission 3

Common Pitfalls to Avoid

• Using serology as the primary diagnostic method or to confirm eradication 1
• Failing to stop PPIs before testing (can cause false negatives in all tests except serology) 1
• Using rapid in-office serological tests due to their limited accuracy 1
• Testing too soon after completion of eradication therapy (wait at least 4 weeks) 1
• Relying on serologic testing within 6-12 months of eradication therapy 6