ITRACONAZOLE SUSCEPTIBILITIES OF FLUCONAZOLE SUSCEPTIBLE AND RESISTANT ISOLATES OF 5 CANDIDA SPECIES

The in-vitro susceptibilities of 1380 isolates of five Candida species were determined in order to establish whether isolates resistant to f luconazole were cross-resistant to itraconazole. IC50 values were dete rmined by a broth microdilution method. 690 Candida albicans isolates, seven Candida glabrata isolates, seven Candida krusei isolates, 120 C andida parapsilosis isolates and 37 Candida tropicalis isolates were s usceptible to both fluconazole (IC50 less than or equal to 32 mg/L) an d itraconazole (IC50 less than or equal to 4 mg/L). Twenty eight of 16 0 C. albicans isolates (17.5%), 180 of 293 C. glabrata isolates (61.4% ), six of 48 C. krusei isolates (12.5%), and 10 of 18 C. tropicalis is olates (55.5%) resistant to fluconazole (IC(50)greater than or equal t o 64mg/L) were also resistant to itraconazole (IC50 greater than or eq ual to 8 mg/L). In contrast, drug-specific resistance to itraconazole was not observed in any of the isolates tested. However, the itraconaz ole IC(50)s for fluconazole susceptible isolates were lower than those for fluconazole resistant isolates, which suggests that patients who fail fluconazole treatment might require itraconazole at higher dosage s than usual.