Question

what is the substrate in urease test? what is the end products in urease test? Describe the principle of the urease test? what genera is this test helpful in identifying (urease test)?

Answer 1

The substrate in urease test is urea.

The end products in urease test are urea, carbondioxide and water
(NH₂)₂ CO+2H₂O CO2+ H₂O + 2NH₃

Urease test is used to determine the ability of an organism to hydrolyse urea into ammonia and carbon dioxide. The ammonia formed during the reaction turns the media into alkaline, which is indicated by phenol red, changing its color from light orange (at pH 6.8) to pink (at pH 8.1). Rapid urease positive organisms like Helicobacter pylori, turns the medium pink within 24 hours. Weakly positive organisms take several days, whereas negative organisms produce no colour.

Rapid Urease Test (RUT) is a popular and simple test which uses the above principle , for detecting the presence of Helicobacter pylori on gastric mucosa. The test is also known as CLO test (Campylobacter like organism test). It is also useful in identifying several genera and species of Enterobacteriaceae like Proteus spp, Klebsiella spp and Yersinia spp. Also for identifying Cryptococcus spp and Brucella spp.