Morphotypes of Candida albicans. Phase-contrast microscopy

Introduction: Mycological literature is still lacking in distinctive and precisely defined criteria of distinguishing between various morphotypes of Candia albicans. Aim of the study: (I) Establishing of the cultural conditions for growth of yeast, germ tube, pseudohyphae and true hyphae of Candida albicans clinical strain. (II) Documentation of the suspension of morphotypes under phase-contrast microscopy. (III) Characterization of particular morphotypes based on phase- -contrast microscopy. Material and methods: Different nutritional regiments as well as ambient pH and temperature were applied to induce the development of morphotypes, i.e., YPG (yeast extract-peptone-glucose broth medium); AMP (arginine-phosphate modified medium); undiluted and diluted human serum (5%). Morphology of each form was photographed under the phase-contrast microscope using a camera (Docuval, Carl Zeiss, Germany). The morphology index (Mi=ls/d2) was applied in this study to depict each of the particular morphotypes. Results: Induction of pleomorphic cell formation by AMP medium and 5% serum was found to generate a slightly different pattern of morphotypes than that found in undiluted serum. Germ tube was created during unipolar growth of blastoconidial cells. Pseudohyphae showed elliptical shapes with visible constrictions at the septal junctions. Long true hyphae exhibited characteristic solid cross-walls. Conclusions: True hyphal cells located at the periphery of the Candida fungus ball-like conglomerate (enzymatically active) may branch human tissue. The present study shows that conditions of undiluted serum, the temperature of 37°C and pH>7.0 were preferable for true hyphae formation and a large fraction of the cells were induced to germinate.