The cultivation and rapid enzyme identification of DF-2

The investigation of two clinical isolates and two reference strains of DF-2 showed that supplementary cysteine and incubation in a humid atmosphere were important growth-promoting factors for these fastidious, gram-negative bacteria. Broth-base media with phenol red indicator were proven to be satisfactory for carbohydrate fermentation tests. Two four-hour enzyme assays (API ZYM and Rosco Diagnostic Tablets) were used to compare the enzymatic activity of DF-2 with that of 27 species of other non-enterobacterial organisms. The Rosco assay revealed that only the DF-2 strains had a positive alpha-fucosidase reaction, suggesting that this character may provide the means for rapid characterization and identification of these bacteria and also be of value for taxonomic classification. The incongruent results of the API ZYM assay seem to be due to the different substrates of the two assay systems.