5-15: urea hydrolysis test (urease test)

tests for the decarboxylation of urea into ammonia and carbon dioxide (urea hydrolysis)

what is the overall usage for the urea hydrolysis test or urease test

urease enzyme

what is urea hydrolysis catalyzed by

it is the virulence factor; H. pylori urease produces ammonia which counteracts the gastric acids (anti-acid)

why is urease important in Helicobacter pylori (agent of gastric ulcers)

Proteus spp. (including P. mirabilis and P. vulgaris)

Providencia stuartii

Morganella morganii

name the 3 common UTI agents urease is found in

urea and phenol red

state the components of the urea broth

is a pH indicator

- yellow or orange at pH 8.4 or lower

- red or pink (fuchsia) at pH 8.4 or higher

what is the purpose of the phenol red

yellow to pink (fuchsia) color change; means the microbe has urease enzyme and is able to decarboxylate urea into ammonia and carbon dioxide, thus increasing the pH

what does a positive urease test look like; what does this mean

stays yellow

what does a negative urease test look like

first tube is positive because it is pink (fuchsia) - possible microbe is Proteus vulgaris

means that this microbe has urease enzyme and can decarboxylate urea into ammonia and carbon dioxide

which is the positive result and what is the possible microbe; what does this mean