Cystine lactose electrolyte deficient agar

CLED agar (cystine lactose electrolyte deficient medium) is a valuable non-inhibitory growth medium used in the isolation and differentiation of urinary organisms. Being electrolyte deficient, it prevents the swarming of Proteus species. Cystine promotes the formation of cystine-dependent dwarf colonies. Bromothymol blue is the indicator used in the agar, it changes to yellow in case of acid production during fermentation of lactose or changes to deep blue in case of alkalinization. Lactose-positive bacteria build yellow colonies. Bacteria which decarboxylate L-Cystine cause an alkaline reaction and build deep blue colonies