C.L.E.D. AGAR W/ ANDRADE INDICATOR (CYSTINE LACTOSE ELECTROLYTE DEFICIENT AGAR)

C.L.E.D. Agar with Andrade Indicator is a differential culture medium used to isolate and differentiate microorganisms based on lactose fermentation, especially useful for growing pathogens associated with urinary tract infections. This is a modified form of Cystine Lactose Electrolyte Deficient (C.L.E.D.) medium of Brevis. Andrade indicator is added for better differentiation and for better colony appearance.
Beef extract, peptone and tryptone supply the nitrogen, vitamins, amino acids and other nutrients necessary for microbial growth. L-Cystine is a growth supplement for cystine-dependent coliforms, and lactose is the fermentable carbohydrate. The medium contains lactose and a pH indicator that changes color when acid is produced by lactose fermenting microorganisms.
Bromothymol blue acts as a pH indicator, and the Andrade indicator additionally helps to distinguish between microorganisms according to their reactions. Agar contributes the solidifying agent necessary for surface culture.
In general, the medium should not be incubated more than 24 hours for better distinction. A longer incubation time, especially under the dominance of lactose fermenters, could lead to intensive colour changes covering non lactose fermenting bacteria.

Differential culture medium for isolating urinary pathogens and distinguishing microorganisms according to their ability to ferment lactose.