Voriconazole against fluconazole-susceptible and resistant candida isolates: in-vitro efficacy compared with that of itraconazole and ketoconazole.

We compared the in-vitro activity of fluconazole, itraconazole, ketoconazole and voriconazole against 67 blood isolates of Candida spp. exhibiting a wide range of fluconazole MICs (0.125 to >64 mg/L). Voriconazole was the most potent in vitro, followed by itraconazole, ketoconazole and fluconazole. Itraconazole and voriconazole had in-vitro activity against fluconazole-susceptible and -resistant candida isolates. Higher itraconazole and voriconazole MICs were observed in isolates exhibiting higher fluconazole MICs, suggesting cross-resistance. Itraconazole and voriconazole MICs of > or =16 mg/L were observed only in Candida albicans and Candida tropicalis. Candida krusei and Candida glabrata exhibited itraconazole MICs of 0.5-1 mg/L and voriconazole MICs of 0.25-0.5 mg/L.