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

Sandys reported a new technique where the swarming of Proteus on an agar medium could be prevented by restricting the electrolyte content in the culture medium. Sandys Medium was modified by Mackey and Sandys, by replacing mannitol with lactose and sucrose and elevating the concentration of agar and bromothymol blue. The same authors further modified this medium by retaining the lactose (deleting sucrose) and by including L-cystine for promoting the growth of cystine-dependent dwarf coliform colonies. This later modified medium was designated as C.L.E.D. (CystineLactoseElectrolyte-Deficient) Medium. This medium is recommended for use in urinary bacteriology, promoting the growth of all urinary pathogens. C.L.E.D. Agar Medium is also recommended for dip stick procedures and as dip inoculum transport medium for urine specimens.

C.L.E.D. Agar Medium was further modified by Bevis by incorporation of Andrade’s indicator. This medium provides sharper differentiation between lactose-fermenters (LF) and lactose-non-fermenters (NLF). The addition of Andrades indicator enhances the appearance of the colony and aids in the identification of microorganisms. The essential nutrients are supplied by peptone, tryptone and beef extract. Lactose is the carbohydrate source. L-cystine permits the growth of “dwarf colony” coliforms. Addition of Andrade indicator the appearance of colonies and aids in the identification of microorganisms. At different pH values, the colour of the medium varies from the standard medium.

for isolation and di?erentiation of microorganisms based on lactose fermentation