The Journal of Medical Microbiology, Vol 41, Issue 6 389-392, Copyright © 1994 by Society for General Microbiology
Rapid identification of micro-organisms from urinary tract infections by beta-glucuronidase, phenylalanine deaminase, cytochrome oxidase and indole tests on isolation media
G. Giammanco and S. Pignato
Istituto d'Igiene e Medicina Preventiva, Universita di Catania, Italy.
Two commercially available media recommended for the isolation and rapid
identification of Escherichia coli from urinary tract infections were
supplemented with L-phenylalanine and L-tryptophan. The non-selective
medium proved suitable for the direct detection of lactose fermentation,
beta-glucuronidase and phenylalanine deaminase activities, indole
production and the oxidase test. It was highly efficient in making a
presumptive identification at species level of the most common
gram-negative urinary pathogens, E. coli, Proteus mirabilis and Pseudomonas
aeruginosa, that account for c. 85% of all urinary isolates. Among the
gram-positive isolates, most colonies were non-fluorescent and could be
separated into staphylococci and enterococci on the basis of the catalase
test. Fluorescent colonies were found to be Staphylococcus haemolyticus
isolates, 61% of which were fluorescent. The selective medium proved
suitable for the same biochemical tests, with the exception of indole,
which was not visible against the red colour of the medium. Therefore, the
differentiation of P. mirabilis from other Proteus-Providencia species was
impossible on this medium.
