The urease test identifies those organisms that are capable of hydrolyzing urea to produce ammonia and carbon dioxide. It is primarily used to distinguish urease-positive Proteeae from other Enterobacteriaceae. Two media types are commonly used to detect urease activity. Christensen’s urea agar is used to detect urease activity in a variety of microorganisms. Stuart’s urea broth is used primarily for the differentiation of Proteus species. For Christensen’s urea agar, urease production is indicated by a bright pink (fuchsia) color on the slant that may extend into the butt after 1-6 hours of incubation. The culture medium will remain a yellowish color if the organism is urease negative. For Stuart’s urea broth, urease production is indicated by a bright pink (fuchsia) color throughout the broth.
