Cellobiose Arginine Lysine Agar (CAL Agar) is recommended for selective isolation and biochemical characterization of Yersinia enterocolitica. This medium was originally formulated by Dudley and Shotts. It is a differential medium as it differentiates Yersinia on the basis of cellobiose fermentation and lysine or arginine decarboxylation. It is generally used for the isolation and characterization of Y.enterocolitica from faecal specimens as the organism is biochemically similar to other Enterobacteriaceae.