[Rapid differentiation method for Shigella and Escherichia coli--application of Indole (tryptophanase), PGUA (beta-glucuronidase) and ONPG (beta-galactosidase) tests].

For the differentiation of Shigella from Escherichia coli, Indole (tryptophanase), PGUA (beta-glucuronidase) and ONPG (beta-galactosidase) tests were used. A total of 377 Shigella and 124 E. coli strains was examined for each sero- and biosero-type by using these tests. The results were as follows. 1) There were no Shigella strains showing positive reactions for both Indole and ONPG tests. 2) No E. coli strains with Shigella-like characteristics (negative for lysine-decarboxylase, motility and lactose-fermentation tests) showed negative results for both Indole and PGUA tests. 3) The abovementioned strains were classified into twelve types according to the results of these tests. Shigella strains, thus, were differentiated from antigenically Shigella-like E. coli strains. Additional use of these tests together with the conventional methods may valuable for the identification of Shigella strains.