For the isolation and presumptive identification of Enterococci / Group D Streptococci. The aesculin produced by organisms positive for aesculin hydrolysis reacts with ferric citrate to form a dark brown or black complex. Bile salts inhibit Gram-positive organisms other than Enterococci or Group D Streptococci. This medium can also be used for presumptive differentiation of the Klebsiella-Enterobacter-Serratia group from other Enterobacteriaceae.