A 52-year-old man completes a 14-day course of bismuth quadruple therapy for Helicobacter pylori-associated duodenal ulcer. He continues taking his proton pump inhibitor. How should eradication be confirmed?

• A Stool antigen test while continuing the PPI, 1 week after therapy
• B Rapid urease test on routine endoscopy performed 2 weeks after therapy
• C Urea breath test at least 4 weeks after finishing antibiotics, with the PPI withheld for 1 to 2 weeks beforehand ✓
• D Serological IgG antibody titre at 6 weeks to document falling titres

Explanation

Eradication is confirmed with urea breath test, stool antigen, or biopsy-based testing at least 4 weeks after completing antibiotics, because earlier testing can give false positives from residual organisms. Proton pump inhibitors suppress bacterial load and cause false negatives, so they must be stopped 1 to 2 weeks before testing. Serology detects past exposure rather than active infection and cannot distinguish current from cleared infection, so it never confirms eradication. Rapid urease testing too soon after therapy is unreliable.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.