Kinetic study of antifungal activity of amphotericin B, 5-fluorocytosine and ketoconazole against clinical yeast isolates using liquid-phase turbidimetry.

The fungal growth of clinical yeast isolates and of VW32 clone of Candida albicans were measured in vitro using a liquid-phase turbidimetric system (Bioscreen from Labsystems, France) in defined conditions. Cultures were performed in Shadomy's liquid medium and the fungal growth automatically evaluated every 10 minutes for 24 hours using various concentrations of drugs. The system made it possible to test 200 culture samples in one experiment. Yeast sensitivity to drugs was also measured by using our routine semi-automatic turbidimetric system. We observed that kinetic patterns of activity of each antifungal agent were typical. The in vitro tests showed that of 927 clinical yeast isolates 99.2% were sensitive to amphotericin B, 94.4% to 5-fluorocytosine and 69.7% to ketoconazole.