Comparison of NCCLS microdilution method and Etest in antifungal susceptibility testing of clinical Trichosporon asahii isolates

• Published in: Diagnostic microbiology and infectious disease 2002-06, Vol.43 (2), p.107-111
• Main Authors: Arikan, Sevtap, Hasçelik, Gülşen
• Format: Article
• Language: English
• Subjects: Amphotericin B - pharmacology; Antibiotics. Antiinfectious agents. Antiparasitic agents; Antifungal agents; Antifungal Agents - pharmacology; Biological and medical sciences; Culture Media; Drug Resistance, Fungal; Fluconazole - pharmacology; Humans; Itraconazole - pharmacology; Medical sciences; Microbial Sensitivity Tests - methods; Pharmacology. Drug treatments; Sensitivity and Specificity; Trichosporon - drug effects
• ISSN: 0732-8893; 1879-0070
• DOI: 10.1016/S0732-8893(02)00376-0

We investigated the in vitro activity of amphotericin B, fluconazole, and itraconazole against clinical Trichosporon asahii isolates ( n = 43) by NCCLS M27A reference microdilution method and explored the correlation between Etest and NCCLS reference method. Microdilution MIC ranges following 48 h of incubation were 1–8, 0.25–16, and 0.06–4 μg/ml for amphotericin B, fluconazole, and itraconazole, respectively. The corresponding Etest MIC ranges were determined as 0.125- > 8, 0.25- > 64, and 0.03–8 μg/ml. Of interest, Etest tended to produce lower amphotericin B MICs and widen the MIC range compared to microdilution. The influence of Etest on fluconazole and itraconazole MICs was in contrary with that observed for amphotericin B. Etest MICs of fluconazole and itraconazole tended to be higher than microdilution MICs. The wider range of amphotericin B MICs obtained by using Etest methodology may facilitate discrimination of isolates with reduced susceptibility to amphotericin B. However, clinical significance of these findings remain yet unknown and determination of MIC breakpoint values is required.