Do incubation temperature, incubation time, and carbon dioxide affect the chromogenic properties of CHROMagar?

Authors: DİLEK YEŞİM METİN, HÜSNÜ PULLUKÇU, SÜLEYHA HİLMİOĞLU POLAT, RAMAZAN İNCİ, ZEKİYE EMEL TÜMBAY

Abstract: On CHROMagar medium Candida species form different colors; thus, the medium enables the differentiation of these species from each other as well as from other Candida species. The aim of this study is to investigate the effect of incubation temperatures, incubation times, and CO_2 on the chromogenic properties of CHROMagar. Materials and methods: A total of 112 strains of Candida spp. were used. A 0.5 McFarland suspension of each strain was inoculated onto CHROMagar with a calibrated loop and incubated at 26 °C and 35 °C for 24-48 h in normal atmosphere and in an atmosphere of 5% CO_2. The results were evaluated at the end of 24 and 48 h by 2 of the authors working in strict separation. Results: The chromogenic property of the medium was best observed at an incubation temperature of 35 °C. Incubation in an atmosphere of 5% CO_2 yielded more prominent colonies at the end of 48 h. The chromogenic differentiation of C. dubliniensis from C. albicans was not easy, for C. albicans yielded a green color and C. dubliniensis a somewhat darker green color. Conclusion: To obtain the best results with CHROMagar, the medium should be incubated at 35 °C for 48 h in an atmosphere of 5% CO_2. A control C. albicans strain should be inoculated on each medium plate to differentiate the color tones of C. albicans and C. dubliniensis.

Keywords: Candida spp., CHROMagar, identification, temperature, incubation time, carbon dioxide

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