Voriconazole and Caspofungin Cidality Against Non-Albicans Candida Species

Caspofungin is generally regarded as fungicidal, and voriconazole is described as fungistatic against Candida species. In this study, we challenged these statements by testing the fungicidal activity of these 2 agents against 197 non-albicansCandida isolates. Minimum inhibitory concentration testing was performed by a microbroth dilution method according to the M27-A2 standard of the Clinical Laboratory Standards Institute, whereas minimum fungicidal concentration determinations were performed by subculturing the contents of each visibly clear well from the minimum inhibitory concentration panel. Fungicidal activity was defined as a 99.9% or greater reduction in the number of colony-forming unit per milliliter. Voriconazole demonstrated greater inhibitory activity than caspofungin against the non-albicans Candida tested and exhibited fungicidal activity against 5% of these strains. Interestingly, almost one third of the non-albicans yeast isolates tested versus caspofungin exhibited fungistatic rather than fungicidal activity. This investigation demonstrates the lack of universal fungicidal and fungistatic activity of caspofungin and voriconazole against non-albicans Candida strains.