Which non-invasive tests are commonly used to diagnose Helicobacter pylori infection?

• A. Urea breath test and stool antigen test.
• B. Endoscopy with biopsy.
• C. Stool culture.
• D. Urine antigen test.

Answer: (A)

Non-invasive testing for active Helicobacter pylori infection relies on detecting either the bacteria’s activity in the stomach or its components in the stool. The most commonly used tests are the urea breath test and the stool antigen test.

The urea breath test works because H. pylori produces urease in the stomach. When a patient ingests labeled urea, urease splits it and releases labeled carbon dioxide. The patient exhales air containing the labeled CO2, and measuring this in the breath indicates whether the bacteria are present in the stomach. It’s highly accurate, non-invasive, and widely used for initial diagnosis and for confirming eradication after treatment.

The stool antigen test detects bacterial antigens shed in stool, reflecting an active infection. It’s convenient, non-invasive, and useful both for diagnosing infection and for verifying eradication later, with good sensitivity and specificity.

Endoscopy with biopsy is invasive, reserved for cases needing direct visualization or tissue assessment. Stool culture can identify the organism and guide antibiotic choices but is technically demanding and not routinely used for initial diagnosis. Urine antigen tests exist but are not as routinely employed as the breath test and stool antigen in standard practice.

So the best answer highlights the non-invasive, routinely used tests: the urea breath test and stool antigen test.