In vitro, Susceptibilities of Clinical Yeast Isolates to Antifungal Drugs of Polyene, Pyrimidine, and Azoles, and their Effect in Yeast Adhesion and Mycelial Formation

In vitro, susceptibilities were determined for 107 clinical isolates of Candida albicans obtained from the laboratory of King Abdulaziz University Hospital (UHC). The agents tested included amphotericin B (as a polyene), flucytosine (as a pyrimidine), and fluconazole (as an azole). MICs were determined by the broth microdilution technique following National Committee for Clinical Laboratory Standards document, using RPMI 1640 broth medium supplemented with 3 g glucose l-1, and the E-test with solidified RPMI 1640 supplemented with 18 g glucose l-1. The susceptibility tests indicated that amphotericin B is the most active fungicidal drug, fluconazole was with less activity and flucytosine was more effective than the later drug. The appropriate rank order of best agreement between the MIC technique, E-test and disk diffusion methods was amphotericin B flucytosine fluconazole. The influence of the tested drugs in adherence of C.albicans on phenyl sepharose (resin) column indicated that amphotericin B was with high antiadherence activity, followed by fluconazole and flucytosine (47, 33 and 18%, respectively.) The effect of the drugs on mycelial formation by the tested C.albicans isolates revealed that amphotericin B showed 71% inhibition of mycelial formation, fluconazole 58% and flucytosine showed about 40% inhibition of mycelial formation