Selective Streptococcus Agar

Streptococcus Selective Agar is a medium used for the isolation of Streptococcus species. Streptococci are commonly isolated from the upper respiratory tract. They are also often isolated from burns and other sites where frequently there is an abundance of competing organisms.

Enzymatic digest of casein and soy peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Organisms positive for esculin hydrolysis hydrolyze the glycoside esculin to esculetin and dextrose. The esculetin reacts with the ferroammonium citrate to form a dark brown or black colony.

Neomycin provides suppression of normal flora for improved recovery of the group A and group B. Colistin breaks the cell membrane of Gram negative microorganisms, especially Pseudomonas species. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bacteriological agar is the solidifying agent.