Germ Tube Formation of Candida albicans in Corn Meal Broth Using the Non-Slip Slide Glass Incubation Method

Candida albicans IFO 1385 yeast cells dominantly develop germ tubes in a dilute corn meal broth at 37˚C. For germ tube (GT) development the broth concentration is optimal at 75 % of the original, and the inoculum is optimal at 105 cells/mL. Incubation proce-dures were compared and the non-slip slide glass incubation (NSSI) method was found to be more available than the tube incubation method or slid-covered slide glass incu-bation method. The GT formation was completed in 1 to 2 h in the NSSI method and clear-cut GTs were observed under optical microscopy. GTs were formed in all 111 test-strains of C. albicans but not at all in other species of Candida. Therefore, under optimal conditions, the rate of identifying C. albicans is 100%, demonstrating that GT detection with the NSSI method is a rapid and reliable identification method. The humid NSSI method is suited for continuous observation of a GT. The initially formed GT elongated to resemble a true hypha, attaching no chlamydoconidium. The hypha subsequently dissociated yeast-like cells. Key words: Candida albicans; corn meal broth; germ tube formation; non-slip slide glass incubation method Since the germ tube (GT) is a characteristic morphology observed only in C. albicans, con-firmation of GT is available as a rapid method for identifying C. albicans. GT formation was first reported by Reynolds and Braude (1956). They observed yeast cells transforming into filamentation (germ) tubes in human blood, sera, plasma and cerebrospinal fluids. Since then, many substances were reported as GT inducers, such as serum (Taschdjian et al.