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

Abstract

We conducted a prospective evaluation of Candida ID chromogenic medium (bioMérieux, Marcy l'Etoile, France) with 786 clinical specimens in comparison with Candiselect medium (Bio-Rad, Marnes la Coquette, France). Candida ID chromogenic medium identified 97.7% of Candida albicans strains; enabled presumptive identification of C. tropicalis, C. lusitaniae, C. guillermondii, and C. kefyr and better detection of yeast combinations (11.4% more often); and was more sensitive for the isolation of filamentous fungi (17.7% more often). However, Candida ID chromogenic medium appeared to be less selective vis-à-vis bacteria, with bacterial colonies sometimes pigmented blue.The increasing frequency of fungal infections is being accompanied by a diversification in the fungal species involved (2, 7). While Candida albicans is still the most commonly isolated yeast, the frequencies of isolation of non-C. albicans yeast species are steadily increasing (1). Rapid and accurate diagnosis of mycological infections is required before the appropriate treatment can be instigated. Several chromogenic media for isolation and identification of C. albicans in a single step according to the characteristic pigmentation of the colonies are available; the use of such media also makes it easier to detect yeast combinations (4). Candida ID chromogenic medium (CAID; bioMérieux, Marcy l'Etoile, France) has recently been developed and marketed for the identification of C. albicans (blue colonies) and the presumptive identification of the yeasts Candida tropicalis, Candida lusitaniae, Candida kefyr, and Candida guillermondii (pink colonies). Our aim was to make a prospective evaluation of the performance of CAID in comparison with that of Candiselect medium (CS; Bio-Rad, Marnes la Coquette, France) with clinical specimens. CS is the routine medium used in our laboratory and was considered the reference medium in this study.Seven hundred eighty-six clinical samples (192 respiratory samples, 182 urine samples, 95 stool samples, 149 samples from the mouth and nose, 68 vaginal samples, 34 catheters, 18 skin swabs, 20 peritoneal fluid samples, 28 samples from other sources) were prospectively inoculated on both CS and CAID at the same time. The plates were incubated at 35°C for 7 days and were read every 24 h. All isolates were analyzed macroscopically according to the manufacturers' recommendations and were then identified by conventional methods. The yeasts were identified on the basis of their microscopic morphologies on potato-carrot-bile medium (Bio-Rad) after 48 h at 27°C and on the basis of their physiological characteristics (Galeries Auxacolor [Bio-Rad] and, if necessary, ID 32C [bioMérieux]) and/or immunological characteristics (Bichrolatex albicans and Krusei color; Fumouze, Levallois-Perret, France). Filamentous fungi were identified on the basis of their morphological characteristics directly on the primary culture or after reinoculation at 27°C on 2% malt medium. For each medium, we noted the following parameters: number of positive cultur...

Phenotypic and Molecular Characterization of Candida nivariensis sp. nov., a Possible New Opportunistic Fungus

“…Surface growth on broth cultures was determined with yeast peptone dextrose (YPD) broth incubated at 37°C for 72 h. The strains were subcultured on CHROMagar Candida medium (Becton Dickinson, Heidelberg, Germany), incubated at 37°C, and examined after 24 to 72 h for colony color and morphology. Germ tube tests were performed by inoculating 2.0 ml of fresh, pooled, normal human serum with a fresh colony and incubation at 37°C for 2 h. To induce chlamydospores and pseudohyphal production, yeasts were incubated on potato carrot bile medium (Bio-Rad) and diluted milk medium (170 ml of natural milk, 1 liter of distilled water, and 0.25 g of chloramphenicol) for 24 to 48 h at 30°C (3,4,11,13,17). The induction of a possible ascosporic state was performed by using acetate ascospore agar (potassium acetate, 5.00 g; yeast extract, 1.25 g; dextrose, 0.50 g; agar, 15.00 g; distilled water, 500 ml), Gorodkowa medium (dextrose, 1.25 g; NaCl, 2.60 g; beef extract, 5.00 g; agar, 5.00 g; distilled water, 500 ml), and V-8 medium for ascospores (V-8 vegetable juice, 500 ml; dry yeast, 10 g; agar, 10 g; distilled water, 500 ml) and incubating yeasts for up to 1 month at 25°C (10).…”

Performance of CHROMAGAR candida and BIGGY agar for identification of yeast species

“…Several chromogenic media for isolation and identification of Candida species are available [12]. These media are based on the formation of various colored colonies with different morphology which result from the cleavage of chromogenic substrates by species specific enzymes [13].…”

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

“…Candida ID (CAID) (bioMérieux) differentiates three groups of yeasts based on the color of colonies: blue colonies for C. albicans, pink colonies for C. tropicalis, C. guilliermondii, Candida kefyr, and Candida lusitaniae, and white colonies for the rest of the species (14,21,28).…”