In vitro investigation of antifungal activities of phenotypic variation Candida albicans strains against fluconazole, itraconazole and voriconazole.

The aim of this study was to investigate the susceptibility of the different phenotypes of Candida albicans strains isolated from clinical specimens to three antifungal agents, fluconazole, itraconazole and voriconazole. Totally 215 specimens were collected from oropharyngeal, gastrointestinal and urogenital tracts of non-neutropenic patients who had received no previous prophylactic treatment. Each of the 215 C. albicans strains recovered was found to express one of the six phenotypes: smooth 73%, fuzzy 10.7%, irregular 2.3%, star 2.8%, ring 6% or stipple 5.1%. The mean MICs for the six phenotypes of C. albicans strains ranged between 0.25 microg/ml and 64 microg/ml for fluconazole, 0.03 microg/ml and 1 microg/ml for itraconazole and 0.03 microg/ml and 0.5 microg/ml for voriconazole. The mean minimum inhibitory concentration (MIC) of fluconazole was consistently higher for C. albicans strains expressing the stipple phenotype. The antifungal susceptibility of the phenotypic switching requires attention, especially in patients who are clinically unresponsive to fluconazole chemotherapy or in cases of serious C. albicans infections of immunocompromised hosts.