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Three approaches were used to characterise 13 reference strains of non-pigmented Prevotella (Bacteroides) spp. and 91 clinical isolates from 21 adult patients with periodontal diseases. Strains were examined in tests for: (1) biochemical and morphological characters comprising microscopic and colonial appearance, biochemical and fermentation activity, tolerance of bile salts and dyes, susceptibility to antibiotic disks and fluorescence under U.V. light; (2) production of volatile and non-volatile fatty acids by gas-liquid chromatography (GLC); and (3) preformed enzymes profiles. Species were distinguished by: hydrolysis of hippurate, starch and acsculin; fermentation of lactose, sucrose, rhamnose, xylose, arabinose, cellobiose, salicin, inulin and xylan; tolerance of Victoria blue 4R; and fluorescence. In GLC analysis, production of propionic, iso-butyric, iso-valeric and phenylacetic acids gave useful discrimination between species. Discriminatory enzyme profiles were obtained with tests for β-xylosidase, β-glucuronidase, β-glucosidase, α-fucosidase, β-N-acetylglucosaminidase and α-mannosidase. Correlation between the three approaches was good and an identification scheme was designed for non-pigmented Prevotella spp. Of the 91 clinical isolates from adult periodontal diseases, 63 gave results identical with those of reference strains and 21 showed only minor variation. The commonest species were P. buccae (42 isolates), P. veroralis ( I5 isolates) and P. oralis (eight isolates).Keywords: Prevotella; oral flora; periodontal disease; identification; gas-liquid chromatography; enzyme tests. |
