Which enzyme does H. pylori produce that allows the urea breath test to work?

Which enzyme does H. pylori produce that allows the urea breath test to work?

• A. Amylase
• B. Protease
• C. Lipase
• D. Urease

Answer: (D)

The urea breath test hinges on Helicobacter pylori’s urease enzyme. H. pylori makes urease, which hydrolyzes ingested urea into ammonia and carbon dioxide. In the test, the patient drinks urea labeled with a carbon isotope. If the bacteria are present, urease converts the labeled urea, and the labeled CO2 is released into the bloodstream, reaches the lungs, and is exhaled in breath where it can be detected. A positive result reflects active infection because it depends on ongoing urease activity. The other enzymes listed—amylase, protease, and lipase—don’t act on labeled urea to produce detectable breath CO2, so they aren’t used in this assay.

The urea breath test hinges on Helicobacter pylori’s urease enzyme. H. pylori makes urease, which hydrolyzes ingested urea into ammonia and carbon dioxide. In the test, the patient drinks urea labeled with a carbon isotope. If the bacteria are present, urease converts the labeled urea, and the labeled CO2 is released into the bloodstream, reaches the lungs, and is exhaled in breath where it can be detected. A positive result reflects active infection because it depends on ongoing urease activity. The other enzymes listed—amylase, protease, and lipase—don’t act on labeled urea to produce detectable breath CO2, so they aren’t used in this assay.