CLED Agar (BROLACIN Agar)

EMD Cat. No. 1.01638.0500

500 g

For the enumeration, isolation and preliminary identification of microorganisms in urine.

Diagnosis of asymptomatic urinary tract infections depends on the detection of a significant bacteriuria, which is defined at the presence of at least 100,000 bacteria in 1 ml of morning urine.

Experimental Procedure and Evaluation	Quality Control
Typical Composition (g/liter)	Literature
Picture/Image

Mode of Action
This culture medium promotes the growth of all microorganisms found in urine. It is also an excellent universal culture medium owing to its wide spectrum of nutrients, lack of inhibitors and the fact that it allows a certain degree or differentiation between the colonies. It contains lactose as a reactive compound which, when degrated to acid, causes bromothymol blue to change its color to yellow. Alkalinization produces a deep blue coloration. The lack of electrolytes suppresses the swarming of Proteus (SANDYS 1960).


Typical Composition (g/liter)
Peptones 7.0; yeast extract 2.0; meat extract 2.0; L-cystine 0.128; lactose 10.0; bromothymol blue 0.03; agar-agar 12.0.


Preparation
Suspend 33 g in 1 liter of purified water. Autoclave (15 min at 121°C), pour plates.
pH: 7.3 ± 0.2 at 25°C.
The plates are clear and bluish green.


Experimental Procedure and Evaluation
Inoculate by spreading a defined quantity (up to 1 ml) of the urine sample (dilute if necessary) or material to be tested on the surface of the plate.
Incubation: 24 hours at 35°C aerobically.

Appearance of Colonies	Microorganisms
Large, golden yellow, surrounding medium is yellow	Escherichia coli, lactose-positive Citrobacter and others
Large, golden yellow, usually mucoid, surrounding medium is yellow	Enterobacter, Klebsiella and others
Large, colouless, surrounding medium is blue	Proteus, Serratia and others
Large, brownish centre, surrounding medium is blue	Pseudomonas
Pale yellow, small, opaque	Streptococci
Deep yellow, very small, opaque	Staphylococci

Quality control (spiral plating method)

Test strains	Inoculum	Recovery	color change	Swarming
	(cfu/ml)	rate (%)
Escherichia coli ATCC 11775	10³-105	70	yellow
Salmonella typhimurium ATCC 13311	10³-105	70	blue
Shigella flexneri ATCC 29903	10³-105	70	blue
Proteus mirabilis ATCC 29906	10³-105	70	blue	none / poor
Proteus vulgaris ATCC 8427	> 105	70	blue	none / poor
Pseudomonas aeruginosa ATCC 27853	> 105	70	blue
Staphylococcus aureus ATCC 6538-P	10³-105	70	yellow

Literature

SANDYS, G.H.: A new method of preventing swarming of Proteus sp. with a description of a new medium suitable for use in routine laboratory practice. - J. Med. Lab. Technol., 17; 224-233 (1960)