[Rapid glutamic acid decarboxylase test for identification of Escherichia coli]

A rapid, one-step glutamic acid decarboxylase test for the identification of Escherichia coli is described. The test gives a positive reaction (definite blue color) after 2 h to 3 h. Disturbing factors were explained. Microorganisms were cultured to Endo agar (SIFIN) supplemented with 1% meat peptone (Berlin-Chemie). For rapid liberation of the enzyme a combination of lytic agents NaCl and Triton X-100 were necessary. A total of 6,867 strains of Enterobacteriaceae of clinically isolates were parallely tested to activity of lactose, indole, citrate respectively biochemical tests with 15 reactions on the one side and activity of lactose and glutamic acid decarboxylase on the other side. 99.2% of the E. coli strains gave a positive reaction with glutamic acid decarboxylase. The rapid test selected E. coli with more reliability than the combination of the lactose, indole and citrate reactions. Expenditure of time and materials was fewer.