In vitro activities of isavuconazole against opportunistic filamentous and dimorphic fungi

The in vitro activity of isavuconazole was compared to those of amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, and ravuconazole against 300 clinical isolates of Pseudallescheria boydii, Paecilomyces lilacinus, Fusarium spp., Bipolaris spicifera, Curvularia lunata, Alternaria alternata, Exophiala spp., Rhizopus arrhizus, Mucor circillenoides, Absidia corymbifera, Blastomyces dermatitidis, Histoplasma capsulatum and Coccidioides posadasii. MICs were determined by a broth macrodilution method based on the CLSI M38-A procedure. The triazoles were relatively uniform in that they showed strong in vitro inhibitory activity against most of the tested fungi. In vitro activity was variable with strains of P. lilacinus while with Fusarium spp., the triazoles were found to have limited in vitro activity and amphotericin B was moderately active. The results suggest that isavuconazole is a broad-spectrum antifungal agent, effective against a wide range of moulds in vitro.