[Dormancy of Candida albicans ATCC10231 in the presence of amphotericin B. Investigation using the scanning electron microscope (SEM)]

Abstract

Objectives: The aim of this study was to visualize the morphology of Candida albicans ATCC10231 in the absence and in the presence of amphotericin B at 0.4 μg/mL, to better understand the phenomenon responsible for a large portion of cases of treatment failure called "dormancy phenomenon". The main objective was to determine the morphological changes adopted by C. albicans in the lag phase extended before resuming normal growth.

Materials and methods: In order to define the morphological characteristics and surface properties of the cells in the absence and in the presence of amphotericin B at 0.4 μg/mL, cells were cultured in Sabouraud medium at 30°C, and the morphology index was determined by reference to the classification of forms in C. albicans determined by Merson-Davies and Odds. Then, the technique of scanning electron microscopy (SEM) coupled with image analysis was used to measure the surface and determined the morphological properties using the plugin analysis three-dimensional (3D) integrated into the ImageJ software.

Results: The dormant phase in C. albicans ATCC10231 grown in Sabouraud liquid at 30°C in the presence of amphotericin B at 0.4 μg/mL extends to 21 hours. The index morphology obtained for the two samples (in the absence and presence of amphotericin B) indicates that the cell even in the presence of amphotericin B retains its yeast form (Mi<1.5) The analysis of microphotography obtained by scanning electron microscopy (SEM) has shown that the cell in the presence of amphotericin B is partially deformed; the deformation is estimated at 33.25%, with various changes in the cell surface.

Conclusion: This study showed that the morphology of C. albicans ATCC10231 in the presence of amphotericin B at 0.4 μg/mL changes with partial deformation of the cell. This rate is insufficient to induce cell death, which partly explains the phenomenon of dormancy adopted by C. albicans prior to cell repair and resume normal growth.

Keywords: Amphotericin B; Amphotéricine B; Candida albicans; Cell deformation; Dormance; Dormancy; Déformation cellulaire; ImageJ; Indice de morphologie; Microscopie électronique à balayage (MEB); Morphology index; Scanning electron microscopy (SEM).