When to Retest for H. pylori After Quadruple Therapy
H. pylori should be retested at least 4 weeks after completion of quadruple therapy using either a urea breath test or a validated monoclonal stool antigen test. 1, 2
Timing of Test of Cure
The minimum waiting period is 4 weeks after treatment completion to allow adequate time for gastric mucosa recovery and to avoid false-negative results from temporary bacterial suppression rather than true eradication 1, 2, 3
In cases of bleeding peptic ulcers specifically, testing may be delayed to 4-8 weeks after the bleeding episode 1, 2
Testing performed earlier than 4 weeks risks false-negative results because the gastric mucosa has not fully recovered from treatment effects 2
Recommended Testing Methods
Non-invasive testing is preferred for confirmation of eradication:
Urea breath test (UBT) is the gold standard with sensitivity of 94.7-97% and specificity of 95-100% 1, 2
Laboratory-based validated monoclonal stool antigen test is an equally accurate alternative with sensitivity and specificity >90%, particularly useful when patients must continue PPI therapy 2, 3
Serology has no role in determining eradication success 1, 2
Critical Pre-Testing Requirements
To ensure accurate results, patients must discontinue medications before testing:
Proton pump inhibitors (PPIs): withhold for at least 7-14 days (preferably 2 weeks) 2
Antibiotics and bismuth: withhold for at least 4 weeks 2
Fasting: patients should fast for at least 6 hours before testing 2
Clinical Scenarios Requiring Mandatory Confirmation
Test of cure is now considered standard of care for all patients, but is absolutely mandatory in:
Gastric ulcer cases: require endoscopic follow-up to ensure complete healing and confirm H. pylori eradication 2
Gastric MALT lymphoma: require upper endoscopy with biopsy-based testing for confirmation 2
Complicated peptic ulcer disease or bleeding ulcers: must confirm eradication before discontinuing PPI therapy 2
Patients with persistent symptoms: indicating possible treatment failure requiring a different eradication regimen 2
Management Based on Test Results
If H. pylori persists after quadruple therapy:
A second, different eradication regimen must be used, as persistent infection is a negative prognostic marker for ulcer recurrence, complications, and treatment failure in MALT lymphoma 2
After two treatment failures, antimicrobial susceptibility testing should be performed whenever possible to guide third-line therapy 1, 3
If susceptibility testing is unavailable, use antibiotics not previously administered or for which resistance is unlikely (amoxicillin, tetracycline, bismuth, or furazolidone) 4
Common Pitfalls to Avoid
Do not test too early: Testing before 4 weeks will yield unreliable results 1, 2
Do not continue PPIs during testing: This causes false-negative results; discontinue for at least 7-14 days 2
Do not use serology: It cannot distinguish active infection from past exposure 1, 2
Do not skip confirmation testing: Even in asymptomatic patients, confirmation provides indirect measurement of resistance patterns in the population and ensures true eradication 2