Citrate mannitol agar medium for separating Escherichia coli paracolons from Shigella.

A culture medium is described which not only differentiates Shigella from Escherichia coli but also serves as the basis for an extremely simple test which specifically identifies E. coli. A test that will identify an organism as E. coli is more useful than one that merely groups this species with other non-Shigella organisms. The theoretical basis for specificity of the test for E. coli and other uses for the medium are discussed.