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

Abstract

Candida ID, a new chromogenic medium, allows identification of Candida albicans (blue colonies) and preliminary identification into a group of four species (pink colonies). In comparison with Albicans ID2 and Sabouraud gentamicin chloramphenicol on 446 fungal strains, Candida ID allowed the isolation of more species than Albicans ID 2 (95.5% versus 91.2%).Mycoses are a growing medical problem requiring prompt diagnosis with species identification and early adapted antifungal therapy (3,7,11,14). 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. CAID was developed to improve the isolation of yeasts, the identification of Candida albicans and C. dubliniensis, the detection of mixed cultures, and the preliminary identification of other species (C. tropicalis, C. guilliermondii, C. kefyr, and C. lusitaniae, which produce pink colonies). Further testing has to be performed to separate these four species. In our study, CAID was compared with Albicans ID2 (AID2) (bioMérieux) and Sabouraud gentamicin chloramphenicol agar (SGC) using 307 collection strains and 139 strains from 220 clinical samples.A total of 307 fungal strains (247 yeasts and 60 filamentous fungi) from bioMérieux and Grenoble hospital collections were tested on the three media. The collection strains were subcultured on Sabouraud agar plates and incubated for 2 to 5 days at 35 or 27°C according to the species. For all isolates, a suspension of the organisms was made in physiological saline and seeded onto three plates (CAID, AID2, and SGC). The plates were incubated at 35°C except for Penicillium and Fusarium spp., which were incubated at 27°C. Equivalent amounts of each of the 220 clinical samples were directly applied to the three media and incubated at 35°C. The reading of the plates and interpretation of the results were carried out after 24, 48, and 72 h of incubation. The determination of the color, the number, and the diameter of the different colonies grown on CAID, AID2, and SGC was performed at each reading step. The colonies showing different morphologies on media inoculated with clinical samples were picked up and identified by conventional mycological methods (15): Bichrolatex albicans, Krusei color (Fumouze, Levallois-Perret, France) (13), ID32C (bioMérieux), and macroscopic and microscopic observations. The colony detections on CAID, AID2, and SGC were compared and analyzed in terms of sensitivity (number of true positives/number of true positives plus the number of false negatives) and specificity (number of true negatives/number of true negatives plus the number of false positives). The data were statistically analyzed by 2 test. C. albicans identification on CAID and AID2 was analyzed in terms o...

Prospective Evaluation of the New Chromogenic Medium Candida ID, in Comparison with Candiselect, for Isolation of Molds and Isolation and Presumptive Identification of Yeast Species

“…The difference was statistically significant (P ϭ 0.003), and the blue staining was stronger after 24 h of culture on CAID. These results are consistent with those of other investigators (3,5,6,8). The nonpigmented C. albicans isolates usually grew as abundant cultures with confluent colonies which more often remained white on CS than on CAID.…”

Characterization and Susceptibility Pattern of Candida Isolates From Hiv - Seropositive Patients in a Tertiary Care Hospital

“…A major advantage is the ability to detection of mixed cultures of yeast in clinical specimens. Hence CHROM agar Candida would be a useful, cost effective tool for rapid identification of various Candida species directly from clinical samples 2,5,9,21 .…”

Identification of Candida glabrata by a 30-Second Trehalase Test

“…Even more effective would be to combine our 30-s trehalase and maltase tests with Candida ID medium as the isolation medium, since the specificity of C. glabrata identification is enhanced on this medium by the appearance of C. glabrata only as white colonies, not pink colonies (6,9).…”

“…Candida ID agar and CandiSelect agar are chromogenic media on which C. albicans colonies develop a characteristic blue color; in addition, Candida ID agar contains a second substrate which allows the classification of several species (but not C. glabrata) in a group with pink colonies (5,9,26). Thus, for yeasts grown on this medium, only white colonies needed to be tested for trehalase and maltase activities to identify a C. glabrata isolate.…”