Helicobacter pylori is positive for which enzyme used in diagnostic testing?

• A. Catalase
• B. Urease
• C. Lactase
• D. Amylase

Answer: (B)

Urease production by Helicobacter pylori is what makes diagnostic testing possible. The enzyme hydrolyzes urea to ammonia and carbon dioxide, which helps the bacteria survive the acidic stomach by increasing the local pH. This same urease activity is the basis for common tests: in the urea breath test, labeled CO2 is detected in the breath after the patient ingests urea, only if urease is active in the stomach; in the rapid urease test, a gastric biopsy is placed in a urea-containing medium and the pH rise from ammonia production changes the indicator color, signaling infection. Catalase, lactase, and amylase are not used for diagnosing H. pylori because they are not specific diagnostic markers for this bacterium.