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Material Safety Data Sheet

Required Products

Organisms

Organisms in the Clinical sector this product works with:

Dehydrated Culture Media

Sector: Clinical

UREA AGAR BASE

Code: CM0053

An agar base for the preparation of Christensen’s medium to detect rapid urease activity of the Proteae and non-rapid urease activity of some Enterobacteriaceae.

Typical Formula*

gm/litre

Peptone

1.0

Glucose

1.0

Sodium chloride

5.0

Disodium phosphate

1.2

Potassium dihydrogen phosphate

0.8

Phenol red

0.012

Agar

15.0

pH 6.8 ± 0.2

* Adjusted as required to meet performance standards

Directions
Suspend 2.4g in 95ml of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 115°C for 20 minutes. Cool to 50°C and aseptically introduce 5ml of sterile 40% Urea Solution SR0020. Mix well, distribute 10ml amounts into sterile containers and allow to set in the slope position.

Description
Urea Agar Base is recommended for the preparation of Christensen medium1 for the detection of rapid urease activity of the urease-positive Proteae. The urea medium may be used for the detection of urea hydrolysis by some other Enterobacteriaceae but the incubation period is much longer 24-48 hours.

Technique
Heavily inoculate the surface of a Urea Agar slope with a pure culture of the organism to be tested. When inoculated with urease-positive Proteae the reaction is usually complete after 3-5 hours at 35°C: urease-producing organisms hydrolyse the urea to form ammonia, and the medium changes from orange to pink. 40% Urea Solution is supplied, as a sterile solution in ampoules, for the convenient preparation of this medium.

Storage conditions and Shelf Life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Appearance
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Orange coloured gel

Quality control

Positive control:

Expected results

Proteus mirabilis ATCC® 29906*

Urease positive; pink slope

Negative control:

 

Escherichia coli ATCC® 25922*

Urease negative; no colour change

* This organism is available as a Culti-Loop®

Precautions
The alkaline reaction produced in this medium after prolonged incubation may not be caused by urease activity. Check using medium without urea.
Do not heat or reheat the medium because urea decomposes very easily.
For the detection of urease-positive Proteae the reaction must be read within the first 2-5 hours of incubation.

Reference
1. Christensen W. B. (1946) J. Bact. 52. 461-466.

 
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