A comparison of Bacteroides ureolyticus isolates from different clinical sources

Clinical isolates of corroding, gram-negative, anaerobic bacilli (provisionally identified as Bacteroides ureolyticus) from superficial ulcers and soft tissue infections (15), non-gonococcal, non-chlamydial urethritis (12) and adult periodontal disease (14) were compared with reference strains of B. ureolyticus, B. gracilis and Wolinella recta in a series of conventional tests of morphology, biochemical activity, tolerance of dyes and bile salts, and antibiotic sensitivity, gas-liquid chromatographic analysis of metabolic products, and in whole-cell analysis by pyrolysis-mass spectrometry (Py-MS). A numerical taxonomic approach was used with the results of conventional tests and the grouping obtained was compared with that obtained by Py-MS. All the ulcer and soft-tissue isolates and the urethritis isolates were oxidase- and urease-positive and formed a homogeneous set consistent with the reference strain of B. ureolyticus. The dental isolates differed from B. ureolyticus strains and were heterogeneous amongst themselves. None corresponded with the reference strains of B. gracilis or W. recta. The conventional and Py-MS approaches to characterisation produced similar groupings and each distinguished between a single cluster of ulcer-urethritis strains and several clusters of dental strains, although the dendrograms derived from the two approaches differed in the order of the clusters; in the Py-MS dendrogram one subcluster of four dental strains came within the main ulcer-urethritis cluster and a cluster of five ulcer strains was separated as a distinct group.