Urea HiVeg™ Agar Base (Christensen) (Autoclavable

Intended Use

Recommended for the detection of urease production, particularly by members of the genus Proteus.

Composition

Ingredients	g/L
HiVeg™ peptone	1.000
Dextrose (Glucose)	1.000
Sodium chloride	5.000
Disodium hydrogen phosphate	1.200
Potassium dihydrogen phosphate	0.800
Phenol red	0.012
Agar	15.000
Final pH (at 25°C)	6.8±0.2

Formula adjusted, standardized to suit performance parameters

Directions

Suspend 24.01 grams in 950 ml purified/distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 10 lbs pressure (115°C) for 20 minutes. Cool to 45-50°C and aseptically add 50 ml of sterile 40% Urea Solution (FD048) and mix well. Dispense into sterile tubes and allow to set in the slanting position. DO NOT OVERHEAT OR REHEAT the medium as urea decomposes very easily.

Principle And Interpretation

Urea Agar is used to detect urease production. Urea Agar described by Christensen (1,2) detected urease activity by all rapidly urease-positive Proteus organisms and also by other members of Enterobacteriaceae (1) that exhibited a delayed urease reaction (3). This was accomplished by :

adding glucose to the medium.
decreasing the peptone concentration and
decreasing the buffering system, as a less buffered medium detects even smaller amount of alkali (4).

Urea HiVeg™ Agar Base is same as Urea Agar Base except that the animal based peptones are completely replaced with vegetable peptones to avoid the BSE/TSE risks associated with animal peptones.

HiVeg™ peptone is the source of essential nutrients. Dextrose is the energy source. Sodium chloride maintains the osmotic equilibrium of the medium whereas phosphates serve to buffer the medium. Urea is hydrolyzed to liberate ammonia. Phenol red indicator detects the alkalinity generated by visible colour change from orange to pink.

Prolonged incubation may cause alkaline reaction in the medium. A medium without urea serves as negative control to rule out false positive results. Also, all urea test media rely on the alkalinity formation and so they are not specific for determining the absolute rate of urease activity. The utilization of proteins may raise the pH to alkalinity due to protein hydrolysis and excess of amino acids liberation results in false positive reaction.

Type of specimen

Isolated Microorganism from samples.

Specimen Collection and Handling

For food and dairy samples, follow appropriate techniques for sample collection and processing as per guidelines(5,6,7).

For water samples, follow appropriate techniques for sample collection, processing as per guidelines and local standards(8).

After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions

Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.

Limitations

Prolonged incubation may cause alkaline reaction in the medium.
Also, all urea test media rely on the alkalinity formation and so they are not specific for determining the absolute rate of urease activity (6).
The utilization of proteins may raise the pH to alkalinity due to protein hydrolysis and excess of amino acids liberation results in false positive reaction.

Performance and Evaluation

Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.

Quality Control

Appearance
Light yellow to light pink homogeneous free flowing powder

Gelling
Firm, comparable with 1.5% Agar gel

Colour and Clarity of prepared medium
Yellowish orange coloured clear to slightly opalescent gel forms in tubes as slants

Reaction
Reaction of 2.4% w/v aqueous solution at 25°C. pH : 6.8±0.2

pH
6.60-7.00

Cultural Response

Cultural characteristics observed on addition of sterile 40% Urea Solution (FD048) after an incubation at 35-37°C for 18-24 hours.

Organism	Urease
Escherichia coli ATCC 25922 (00013*)	negative reaction, no change
# Klebsiella aerogenes ATCC 13048 (00175*)	negative reaction, no change
Klebsiella pneumoniae ATCC 13883 (00097*)	positive reaction, cerise colour
Proteus mirabilis ATCC 25933	positive reaction, cerise colour
$ Proteus hauseri ATCC 13315	positive reaction, cerise colour
Salmonella Typhimurium ATCC 14028 (00031*)	negative reaction, no change

Key: *Corresponding WDCM numbers.
# Formerly known as Enterobacter aerogenes and $ Formerly known as Proteus vulgariserogenes

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition Seal the container tightly after use. Product performance is best if used within stated expiry period.

Disposal

User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (9,10).

More Information
Product Name	Urea HiVeg™ Agar Base (Christensen) (Autoclavable)
SKU	MV112
Product Type	HiVeg™
Physical Form	Powder
Origin	Animal Free (Veg)
Packaging type	HDPE
References	1. Christensen W. B., 1946, J. Bacteriol., 52:461. 2.MacFaddin J. F., 2000, Biochemical Tests for Identification of Medical Bacteria, 3rd Ed., Williams and Wilkins, Baltimore.Md. 3.Farmer J. J. III, McWhorter A. C., Huntley G. A., Catignani J., J. Clin. Microbiol. 1975: 1 (1): 106-107. 4.MacFaddin J. F, 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. 1, Williamsand Wilkins, Baltimore, Md. 5.American Public Health Association, Standard Methods for the Examination of Dairy Products, 1978, 14th Ed., WashingtonD.C. 6.Salfinger Y., and Tortorello M.L. Fifth (Ed.), 2015, Compendium of Methods for the Microbiological Examination ofFoods, 5th Ed., American Public Health Association, Washington, D.C. 7.Baird R.B., Eaton A.D., and Rice E.W., (Eds.), 2015, Standard Methods for the Examination of Water andWastewater, 23rd ed., APHA, Washington, D.C. 8.Isenberg, H.D. Clinical Microbiology Procedures Handbook. 2nd Edition. 9.Jorgensen,J.H., Pfaller , M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015)Manual of Clinical Microbiology, 11th Edition. Vol. 1. 10.Wehr H. M. and Frank J. H., 2004, Standard Methods for the Microbiological Examination of Dairy Products, 17th Ed.,APHA Inc., Washington, D.C.
Customized Product Available	No