Helicobacter pylori is characterized by its ability to produce urease, an enzyme capable of breaking down urea into ammonia and bicarbonate, according to the following reaction:
The high local concentration of ammonia allows the bacterium to survive even in a gastric environment with very low pH.
The cleartest test is a rapid qualitative test for the detection of Helicobacter pylori in biopsies.
To selectively identify Helicobacter pylori with high sensitivity, the test uses the pH change caused by the production of ammonia from urease, as demonstrated by the color change of a pH indicator, which shifts from yellow to bright fuchsia (Magenta).
Both the reagent and the ready-to-use device have been designed to maximize the sensitivity and simplicity of the test.