Bile Esculin Azide Broth, Modified

Bile Esculin Azide Broth,Modified si recommended for differentiating between Enterococci and Group D Streptococci.This medium is similar to the medium developed by Isenberg et. al. but with agar omitted. Tryptone, peptone and yeast extract serve as a source of carbon, nitrogen compounds, long chain amino acids, vitamins and other essential nutrients. Sodium azide inhibits growth of gram-negative organisms and permits the cultivation of Enterococci and group D Streptococci. Bile inhibits gram-positive bacteria other than Enterococci. Sodium citrate acts as a buffering agent. Esculin is hydrolysed by Enterococci and group D streptococci to esculetin which reacts with ferric ammonium citrate to form dark brown or black complex, hence blackening of the medium.