Antifungal Susceptibility testing: New trends

摘要

Development of standardized antifungal susceptibility testing methods has been the focus of intensive research in the last 15 years. Antifungal sensitivity tests were done for selected (46) fungal isolates, (23 dermatophytes and 23 Candida ) by E-test and broth microdilution method. E-test gave better sensitivity results on Candida species than dermatophytes for all drugs expect itraconazole. We compared E-test versus broth microdilution method for testing dermatophytes. The sensitive cases obtained by broth microdilution method were (13% for amphotericin B, 21% for fluconazole, 21% for ketoconazole and 69% for itraconazole) higher than those obtained by E- test (8% for amphotericin B, 8% for fluconazole, 4% for ketoconazole and 34% for itraconazole) for all tested drugs. The difference was significantly higher in broth microdilution method than E-test for itraconazole (P=0.02). On comparing both methods of antifungal susceptibility for Candida species, there was insignificant lower sensitivity to amphotericin B, fluconazole and itraconazole by E-test than broth microdilution (p0.05) with similar sensitivity to ketoconazole.In conclusion - Broth microdilution method is the preferred method for antifungal susceptibility of dermatophytes.- E-test is simple method, easy to perform on both dermatophytes and Candida. However it is expensive and difficult in defining the precise borders of the inhibition zones particularly for fluconazole (fungistatic), and on dermatophytes (unequal distribution of inoculum on agar plates ).