BILE ESCULIN DISCS

Group D streptococci hydrolyze esculin to esculetin and dextrose. Esculetin reacts with an iron salt such as ferric citrate
to form a blackish brown coloured complex. Rochaix found that esculin hydrolysis is an important criteria in the
identification of enterococci. Meyer and Schonfeld observed that when bile was added to esculin medium, around 60%
enterococci were able to grow and split the esculin while other streptococci could not. When a comparative study was
performed by Facklam and Moody for presumptive identification of Group D streptococci, they found the bile esculin
test as a reliable means of identifying Group D streptococci and differentiating them from other streptococci groups.

For detection of esculin hydrolysis in the presence of bile.