Nutrient medium intended for generation of the agents of enteric yersiniosis and pseudotuberculosis. The growth of gram-positive and gram-negative microflora is inhibited. Escherichia coli and Shigella become yellow, via the fermentation of glucose. Yersinia turns yellow within the first 24 hours, as they are also fermented glucose. On the second day of incubation Yersinia breaks down urea and their colonies take on a blue color. Other urea positive microorganisms acquire blue color, slippery, indistinct colonies.