HiCrome MS.0157 Agar is a selective medium recommended for the simultaneous detection of Escherichia coli, Escherichia coli 0157:H7 and coliforms in water and food samples. Escherichia coli 0157:H7 gives colorless colonies because of non-fermentation of sorbitol and absence of β-glucuronidase activity, whereas other strains of Escherichia coli having β-glucuronidase activity and fermenting sorbitol appear as steel blue colored colonies. In absence of tellurite various non Escherichia coli 0157:H7 may have some colony color. Addition of tellurite makes medium much more specific and selective.
