Levine Agar or Eosin Methylene Blue Agar (EMB) is a mildly selective medium for the study and differentiation of lactose-fermenting and non-lactose-fermenting Enterobacteriaceae in foods, dairy products and clinical samples. It is used for the examination of samples of sanitary importance for the presence of coliforms. Eosin and methylene blue, contained in the medium, inhibit the growth of Gram-positive bacteria. The good correlation between the two dyes makes it possible to distinguish lactose-fermenting from non-fermenting Enterobacteriaceae, based on the ability of the microorganism to adsorb the dye. Coliforms, which are lactose-fermenting organisms, are identified as blue-black colonies. Non-lactose-fermenting organisms, such as Salmonella and Shigella, have colourless, transparent or amber colonies. Some strains of E. coli, but not all, will produce a "green glow" on this medium.