Evaluation of a commercial medium for identification ofCandida species

Abstract

CHROMagar Candida (CHROMagar, France) was evaluated as a medium for the presumptive identification and isolation of yeasts using 1,537 isolates of medically important yeasts, including 970 Candida albicans, 165 Candida parapsilosis, 131 Candida glabrata, 62 Candida guilliermondii, 35 Candida krusei, 32 Candida tropicalis, 31 Rhodotorula rubra, 23 Trichosporon spp. (17 Trichosporon beigelii), 17 Candida famata, 16 Candida pelliculosa, 10 Pichia etchelsii, 10 Saccharomyces cerevisiae, 8 Candida lusitaniae, 7 Cryptococcus spp., and 20 isolates of other Candida spp. After 48 h of incubation at 37 degrees C, the sensitivity and specificity were, respectively, 99% and 100% for Candida albicans, 93.8% and 99.1% for Candida tropicalis, and 100% and 100% for Candida krusei. In addition to colony color, other colony characteristics were important for identification of some species, such as rough colonies in Candida krusei isolates or the halo around the colonies of Candida tropicalis. A great variety of colors was observed among species other than Candida albicans, Candida tropicalis, and Candida krusei. For identification purposes, CHROMagar Candida medium has an accuracy similar to that of germ-tube tests and chlamydospore development tests for Candida albicans and to that of the ATB ID32C kit (API, bioMérieux, France) for Candida tropicalis and Candida krusei.

The Ins and Outs of DNA Fingerprinting the Infectious Fungi

“…Finally, even if cells are clonally plated, the agar must be of the correct composition to discriminate among species, strains or switch phenotypes. As previously noted, CHROMagar (243,263,324) and similar indicator agars provide a first approximation of heterogeneity in a single plating. Most importantly, multiple clones from each sample should be isolated and analyzed whenever possible to assess the degree of genetic heterogeneity.…”

“…Commercial kits have been available for several years that assess the assimilation of more than 19 carbohydrates as the only source of carbon (50,105,113,120), and their reliability in determining species is quite high (greater than 90%). In addition, an indicator agar referred to commercially as CHROMagar is now available that discriminates colorimetrically between species and is based upon the reduction of unnamed compounds (243,263,324). The CHROMagar method is probably not as discriminatory as the sugar assimilation kits, but the convenience of plating cells on a single indicator agar is unparalleled for preliminary identification of species and as an indicator of population homogeneity.…”

Evaluation of the New Chromogenic Medium Candida ID 2 for Isolation and Identification of Candida albicans and Other Medically Important Candida Species

“…To check the influence of the incubation temperature in the growth of the different species of yeasts on the chromogenic media, 10 l of a yeast suspension that contained between 30 and 300 viable cells grown on Sabouraud agar plates at 37°C was spread on the agar plates, and the number, size, and color of the colonies were registered at different times of incubation (18,24,48, and 72 h) at 37°C or room temperature (18 to 20°C). Growth on Sabouraud glucose agar plates was used as a reference of viability and colony features.…”

Evaluation of Candida ID, a New Chromogenic Medium for Fungal Isolation and Preliminary Identification of Some Yeast Species

“…The importance of identifying the pathogen quickly (20), as well as the difficulty in detecting mixed cultures in the same plate with the traditional Sabouraud glucose agar medium (2), has fostered the development of differential media for the identification of yeasts (1,5,6,8,12,18,19,22). Candida ID (CAID) (bioMérieux, Marcy l'Etoile, France) is a recently commercialized, ready-to-use medium.…”