The urease test differentiates bacteria based on their ability to produce urea, which is hydrolyzed into ammonia and CO2. The test uses Christensen's urea agar, with a preparation and incubation process, and results are indicated by a color change in phenol red from light orange to pink. Rapid urease-positive organisms produce a pink color within 24 hours, while negative organisms show no color change.

1. UREASE TEST

2. PRINCIPLE
☺ This test is used to differentiate the bacteria on the
basis of urea production
☺ Urea is the product of decarboxylation
of amino acids
☺ Hydrolysis of urea produces ammonia and CO2

4. MEDIA USED IN UREASE TEST
 Christensen’s Urea Agar
Compositi
on
KH2PO4-
2gm
+
Peptone-
1gm
Dextrose
-1gm
Phenol
red-.01gm
+
Agar-
15gm
Urea-
20gm
+
NaCl-5gm

5. PREPARATION
☺ Dissolve the ingredients in 100 ml of distilled water and filter
sterilize (0.45-mm pore size).
☺ Suspend the agar in 900 ml of distilled water, boil to dissolve
completely.
☺ Autoclave at 121 degree C and 15 psi for 15 minutes.
☺ Cool the agar to 50 to 55 degree C.
☺ Add 100 ml of filter-sterilized urea base to the cooled agar
solution and mix thoroughly.
☺ Distribute 4 to 5 ml per sterile tube and slant the tubes during
cooling until solidified.

6. PROCEDURE OF UREASE TEST
☺ Streak the surface of a urea agar slant with a portion of a
well-isolated colony of cultured bacteria
☺ Incubate the tube at 35°-37°C for 48 hours to 7 days.
☺ Examine for the development of a pink color for as long as
7 days.

7. +ve
Pink color in
15 min
H.pylori
-ve
No color
change
E.coli
RESULT

9. DISCUSSION
☺ The formation of ammonia alkalinizes the medium, and the pH shift is
detected by the color change of phenol red from light orange at pH 6.8
to magenta (pink) at pH 8.1
☺ Rapid urease-positive organisms turn the entire medium pink within 24
hours
☺ Weakly positive organisms may take several days, and negative
organisms produce no color change or yellow as a result of acid
production

10. THANK YOU