Variable antifungal susceptibility of wild-type Candida albicans phenotypes from neutropenic hosts

The aim of the present study was to investigate the relationship between phenotypes of Candida albicans strains isolated from clinical specimens and susceptibility of the strains to two antifungal agents, itraconazole and fluconazole. Oropharyngeal, gastrointestinal tract, and urogenital tract specimens were collected from 131 neutropenic patients with Candida infection who had received no previous prophylactic treatment. The most frequent species isolated was Candida albicans, followed by Candida glabrata, Candida tropicalis, Candida krusei, and Candida parapsilosis. Each of the 44 Candida albicans strains recovered was found to express one of four phenotypes: smooth, irregular, fuzzy or stipple. Mean minimum inhibitory concentrations (MICs) of itraconazole and fluconazole as determined by the microdilution method and the E-test were consistently higher for Candida albicans strains expressing the stipple phenotype. The mean MICs for the four phenotypes of the Candida albicans strains ranged between 0.35 microgram/ml and 2.41 micrograms/ml for itraconazole and 2.78 micrograms/ml for fluconazole. Antifungal susceptibility of the stipple phenotype requires careful appraisal, especially in patients clinically unresponsive to azole chemotherapy or in cases of life-threatening, deep-seated Candida infections.