CHROMagar™ STEC is designed to detect a wide range of Shigatoxin producing E.coli (STEC).

STEC grow as mauve color colonies, while other bacteria will grow as blue or colourless colonies or are inhibited, making this medium an excellent screening tool, as proven in the recent outbreak of E.coli O104:H4 in Germany (see picture, taken by Dr. Lothar Beutin, from the German Reference Laboratory for E.coli) and another outbreak in Japan with an E.coli O111.