Evaluation of a new dipslide with a selective medium for the rapid detection of beta-glucuronidase-positive Escherichia coli.

A selective medium was incorporated into a new three-media dipslide (Uricult Trio, Orion Diagnostica) to allow rapid identification of Escherichia coli. The medium is supplemented with a recently described chromogenic substrate, hydroxyquinoline-beta-D-glucuronide, for beta-glucuronidase enzyme. The performance of the medium was compared to that of three other beta-glucuronidase detection methods in tests of 602 routine urine samples. Of 324 Escherichia coli strains isolated, 92% grew brown colonies on dipslide, thus being beta-glucuronidase positive. The proportion of beta-glucuronidase-positive Escherichia coli detected by the three methods was 93% for BGA II agar plates (Tammer-Tutka), 91% for PGUA tablets (Rosco) and 84% for Fluorocult Brolacin agar plates (Merck). No false-positive reactions were seen in the case of 209 significant isolates of species other than Escherichia coli grown on the selective medium.