For isolation and differentiation of Escherichia coli O157:H7 from food and environmental samples
CHROMOGENIC EC 0157: H7 AGAR BASE is used for selective isolation and detection of Escherichia coli 0157: H7. This culture media EC O157:H7 is based on the formulation described by Rappaport and Henigh. The medium contains sorbitol and a chromogenic mixture instead of lactose and indicator dyes respectively, as is conventionally used. The chromogenic substrate is specifically and selectively cleaved by E.coli O157: H7 resulting in a dark purple to magenta coloured moiety. This medium contains Casein enzymatic hydrolysate as a source of carbon, nitrogen and growth nutrients. Bile salts and Sodium lauryl sulphate inhibits the growth of the Gram positive microbial flora. Addition of TS 005 (1% Potassium Tellurite Solution) makes the medium selective. Escherichia coli O157:H7 belongs to the Enterohemorrhagic Escherichia coli (EHEC) group and itexists as a food borne pathogen. E.coli O157: H7 was first recognized as a human pathogen in 1982 when two outbreaks of hemorrhagic colitis were associated with consumption of undercooked ground beef that has been contaminated with this organism .