In vitro Susceptibility Testing of Clinical Zygomyceteous Species isolated in Cairo, Egypt against Ten Antifungal Agents by Broth Microdilution, Disk Diffusion and E-test Methods

HIS study was carried out on ten zygomycetous isolates …….belonging to 5 species namely, Rhizopus oryzae (3), Lechtheimia corymbifera (1), Lechtheimia ramosa (3), Syncephalastrum racemosum (2), Rhizomucor pusillus (1), isolated from clinical specimens in Cairo, Egypt. These isolates are classified in 3 families, mucoraceae, lichtheimiaceae, syncephalastraceae of order mucorales. They were tested for their susceptibility to ten antifungal drugs using broth microdilution, disk diffusion, and E-test methods. The antifungals used were amphotericin B, itraconazole, voriconazole, fluconazole, terbinafine, ketoconazole, griseofulvin, caspofungin, micafungin, and posaconazole. A good level of overall agreement between the disk diffusion and the broth microdilution methods was observed in this study, therefore disk diffusion method could be considered as a good alternative to the broth microdilution method. Members of the three families tested were fully susceptible to amphotericin B and itraconazole and completely resistant to voriconazole, griseofulvin, caspofungin, and micafungin. ketoconazole was active against lichtheimiaceae,andsyncephalastraceae while it showed reduced activity to mucoraceae. Fluconazole showed reduced activity against all tested isolates. Terbinafine was inactive against mucoraceae andsyncephalastraceae while it showed reduced activity against isolates of lichtheimiaceae. Although posaconazole was active against syncephalastraceaeand showed reduced activity to lichtheimiaceae, it was inactive to mucoraceae. Variability of in vitro susceptibility was found in all mucorales genera tested therefore susceptibility profile of the isolated etiologic agents must be known before treatment of infections.