BETA-D-GLUCURONIDASE ACTIVITY AMONG PROTOTROPHIC AND AUXOTROPHIC VARIANTS OF ESCHERICHIA-COLI AND OTHER ENTEROBACTERIACEAE COMMONLY IMPLICATED IN URINARY-TRACT INFECTIONS

Glucuronidase (GUD) activity of 102 prototrophic, 91 cysteine-requirin g, and 19 thymidine-requiring strains of Escherichia coli was examined using growth from MacConkey, CLED, and enriched brain heart infusion (BHI) agars. After 24 h incubation, GUD activity was detected in 92%-9 6% of prototrophic strains and a similar proportion of thymidine-requi ring strains with most reactions detectable in shorter incubation peri ods. GUD activity among strains requiring cysteine was significantly l ess than that found amongst prorotrophic strains. The effects of diffe rent sources of inocula were evident in the shorter incubation periods . Other strains of the Enterobacteriaceae and oxidative strains freque ntly implicated in urinary tract infection were also tested. Here, pos itive reactions were detected among Citrobacter and Enterobacter spp, and a strain of Klebsiella oxytoca, but only after 24 h incubation. GU D activity was not detected among the oxidative strains tested under t he same conditions. Although an incubation time of 24 h is necessary t o detect activity in a small number of ''slow hydrolyzing'' E. coli, t he increased sensitivity thus attained compromises the specificity of the test for this organism by simultaneously enhancing detection of th e enzyme in other enterobacteria.