Comparative in vitro activity of voriconazole and itraconazole against fluconazole-susceptible and fluconazole-resistant clinical isolates of Candida species from Spain

The in vitro activity of voriconazole was compared with that of itraconazole against 299 fluconazole-susceptible (MIC less than or equal to 8 mu g/ml) and 130 fluconazole-resistant (MIC greater than or equal to 16 mu g/ml) clinical isolates of Candida spp. An adaptation of the National Committee for Clinical Laboratory Standards reference method was employed for determination of MICs. Voriconazole showed more potent activity than either fluconazole and itraconazole, even against some Candida albicans, Candida glabrata, and Candida krusei isolates resistant to fluconazole, However, for fluconazole-resistant isolates, the MICs of itraconazole and voriconazole were proportionally higher than for fluconazole-susceptible isolates. These data may indicate cross-resistance.