Urease is an enzyme made by some microorganisms (e.g. Proteus vulgaris) to breakdown/hydrolyze urea into carbon dioxide, water, and ammonia. P. vulgaris happens to be able to do this rather quickly as compared to other Proteus species.
An urea broth with pH indicator phenol red is used. The presence of ammonia will cause the phenol red to change color to a deep pink (positive result). If no deep pink color is detected, the result is negative.
Clinical significance. There are only a few enterics classified as “rapid urease positive” organisms due to their ability to hydrolyze urea.
Reference
Cappuccino, J. G., & Welsh, C. (2018). Microbiology: A laboratory manual.
