In vitro activity of fluconazole on Candida albicans

Fluconazole is a triazole antifungal compound suitable for the treatment of fungal infections, including those caused by Candida albicans. Fluconazole, as all azole antifungals, is a potent inhibitor of ergosterol biosynthesis. The aims of this study are to evaluate the susceptibility of C. albicans strains isolated from clinical specimens against fluconazole, and to assess the decrease in ergosterol produced on these strains when they are incubated in vitro with this antifungal compound. Sixty six yeast strains were isolated and identified from vaginal specimens of 710 women of a tocogynecology surgery (9.3%), C. albicans being the most frequent species (n = 52, ca. 79%). An agar dilution technique was used to determine the minimal inhibitory concentration (MIC) of fluconazole for the C. albicans strains. The MICs rank was between 1 and 20 micrograms/ml (mean = 6.6 micrograms/ml). Ergosterol content from ten C. albicans strains (MIC for fluconazole = 5 micrograms/ml) was assessed using the method proposed by Breivik and Owades, with three concentrations of fluconazole (2.5, 5 and 20 micrograms/ml) and four contact times (1, 6, 12 and 24 h), in comparison to no treated strains (control). The mean content of ergosterol was lower in the treated strains than in the control ones, and became statistically significant after 12 h of incubation.