In H. pylori infection, which non-invasive test is the gold standard for confirming eradication after completing treatment, and why is it preferred over serology for this purpose?
- A H. pylori IgG ELISA — because antibody titres fall to negative within 4 weeks of eradication
- B Stool antigen test — because it is cheaper than UBT but equally accurate
- C Urea breath test (UBT) — because it tests for active urease activity and becomes negative after eradication ✓
- D Rapid urease test (CLO test) — because it detects active infection in biopsies
Explanation
The urea breath test (UBT) using 13C- or 14C-labelled urea is the gold standard non-invasive test for confirming H. pylori eradication because it directly tests for active urease activity — labelled CO2 is exhaled only if live H. pylori urease is present. Serological tests (IgG ELISA) cannot confirm eradication as anti-H. pylori IgG antibodies persist for months to years after successful eradication (they decline slowly). The stool antigen test (SAT) using monoclonal antibody ELISA is also acceptable for eradication testing but has slightly lower sensitivity than UBT in practice.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
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