Edward's Medium Base, Modified is a selective medium for the rapid isolation of Streptococcus agalactiae and other Streptococci associated with mastitis and also from other clinical samples. Crystal violet and thallous sulphate serve as the selective agents for Streptococci. Supplementation with blood provides additional nutrients in addition to serving as an indicator of haemolysis. Streptococcus agalactiae appears as colorless colony with zone of haemolysis while Enterococcus faecalis froms black colored colony on this medium.