Damage to yeast cells ofCryptococcus neoformansby voriconazole and fluconazole: a culture and microscopic study

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Abstract
A systematic cultural, cytological and microscopic study of voriconazole (VCZ) and fluconazole (FCZ) damage to Cryptococcus neoformans over time was made. When haemocytometer counts were compared with colony-forming units(cfu) viability decreased with increased drug concentration and prolonged treatment time up to 48 h. Percentage viability by vitalstaining correlated with cfu. Concentrations of VCZ were foundto be 10-fold more potent than FCZ. At 72 h, percentage viability increased 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 cellscharacterized by a large central vacuole easily observed microscopically. Vital staining showed that there was no direct relationship between cytological changes and non-viability. These novelfindings add a new approach for studying the antifungal action of VCZ and FCZ against C. neoformans and provide a new perspective on their antifungal action.

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