Voriconazole is a new triazole antifungal agent with potent activity against yeasts and moulds. We report the in vitro activity of voriconazole against 300 clinical moulds consisting of 50 species belonging to 25 genera. Comparative antifungals were amphotericin B and itraconazole. All isolates were tested by broth microdilution according to the NCCLS M38P methodology. We also attempted to validate a disk susceptibility method to test moulds against voriconazole (10 ug/ml disks) using Mueller-Hinton glucose methylene blue medium. All isolates of moulds tested were able to produce sufficient growth to determine MIC's between 48 and 72 hours. The in vitro activity of voriconazole was more potent or similar to those of itraconazole and amphotericin B for most isolates tested. These results are generally consistent with previous comparisons for the in vitro activity of voriconazole. The following fungi had MIC90's of less than 0.5 ug/ml for voriconazole; Aspergillus fumigatus, A. flavus, A. nidulans, A. niger, A. terreus, Scedosporium apiospermum (Pseudallescheria boydii), Penicillium marneffei, Paecilomyces sp. Bipolaris sp., Curvularia sp., Exserohilum sp., Exophiala sp., Cladophialophora sp., Phialophora sp., Alternaria sp. and Wangiella sp. However, S. prolificans appears to be resistant to all three agents tested. Fusarium isolates were more variable with MIC's ranging from 1-4 uglml, but as with other moulds additional strains need to be tested. Zygomycetous moulds all exhibit elevated MIC's in the range 2-8 ug/ml. voriconazole disk testing was easy to perform and a comparison of zone diameters with MIC's showed the potential of a simple disk test for screening moulds for resistance.
Full conference title:
Focus on Fungal Infections 11, March 14-16 2001
- Focus on Fungal Infection 11 (2001)