DAMAGE TO YEAST-CELLS OF CRYPTOCOCCUS-NEOFORMANS BY VORICONAZOLE AND FLUCONAZOLE - A CULTURE AND MICROSCOPIC STUDY

A systematic cultural, cytological and microscopic study of voriconazo le (VCZ) and fluconazole (FCZ) damage to Cryptococcus neoformans over time was made. When haemocytometer counts were compared with colony-fo rming units (cfu) viability decreased with increased drug concentratio n and prolonged treatment time up to 48 h. Percentage viability by vit al staining correlated with cfu. Concentrations of VCZ were found to b e 10-fold more potent than FCZ. At 72 h, percentage viability increase d in cultures with lower drug concentrations, indicating outgrowth of surviving yeast cells. Drug treatment resulted in a cytological change in a large percentage of yeast cells characterized by a large central vacuole easily observed microscopically. Vital staining showed that t here aias no direct relationship between cytological changes and non-v iability. These novel findings add a new approach for studying the ant ifungal action of VCZ and FCZ against C. neoformans and provide a new perspective on their antifungal action.