[In vitro evaluation of the sensitivity to fluconazole of different species of yeasts isolated in pathology]

In a previous study, the authors developed a technique for evaluating the in vitro susceptibility (or resistance) of Candida albicans to fluconazole, using casitone broth and agar. Photometric readings of growth in liquid media proved more accurate for evaluating antifungal activity and consistently agreed with clinical findings in all studied cases. This method was consequently extended from C. albicans to other yeasts recovered from high-risk patients (C. glabrata, C. famata, C. tropicalis, C. krusei, C. pseudotropicalis, C. parapsilosis, etc...). High resolution antifungal assay medium (broth and agar) and casitone medium (broth and agar) with or without agitation (Autobac System) were used to study the activity of fluconazole against approximately one hundred yeast strains. MICs above 3.12 micrograms/ml were found for several strains, particularly belonging to the C. glabrata and C. krusei species. These values are equal to or greater than serum levels achieved during treatment with fluconazole, a fact which raises practical questions concerning fluconazole therapy and may explain the failure of fluconazole to eradicate yeasts in some patients.