Rapid identification of Capnocytophaga isolated from septicemic patients

Four Capnocytophaga strains from blood cultures of immunocompromised patients with malignant disease and the type strains of three Capnocytophaga species were examined and compared to strains representing five other genera that are hard to differentiate from Capnocytophaga. With three rapid identification methods, negative catalase and oxidase reactions and positive ONPG assay, Capnocytophaga was easily separated from Eikenella corrodens, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, and CDC group DF-2. Haemophilus aphrophilus was excluded by leucine, valine and cystine arylamidase and alpha-glucosidase reactions (API ZYM). Further confirmatory reactions constituted gelatin hydrolysis, haemin requirement, and carbohydrate and esculin breakdown. Although rapid identification of Capnocytophaga to the genus level was feasible, differentiation on a species level proved impossible.