Bile Aesculin Agar

Bile esculin agar (BEA) is a differential and selective medium and is mainly used to discern group D Streptococci and Enterococci based on the organism′s potential to hydrolyze esculin. BEA comprises of oxygall (bile salts, first selective ingredients) and azide (second selective ingredients), former inhibits the growth of gram positive organisms and latter inhibits the growth of gram negative organisms. BEA also comprises of nutrients ferric citrate and esculin, where esculin is a differential ingredient and is also a fluorescent compound, upon hydrolyzation the fluorescence is lost. BEA is used for bile esculin test which is based on the hydrolysis of esculin into esculetin (6, 7-dihydroxy-coumarin) and glucose by a micro-organism that produce an enzyme esculinase.

For the preliminary identification of enterococci (serology group D), as defined by Swan (1954) and Facklam and Moody (1970).

Dissolve 64.5 g in 1 litre distilled water. Bring to a boil while stirring continually. This medium should NOT be autoclaved. Cool to 45-50°C. Mix gently and dispense into sterile Petri dishes.