Quality Control and Reference Guidelines for CLSI Broth Microdilution Susceptibility Method (M38-A Document) for Amphotericin B, Itraconazole, Posaconazole, and Voriconazole

Abstract

Although standard conditions are available for testing the susceptibilities of filamentous fungi to antifungal agents by the Clinical and Laboratory Standards Institute (CLSI; formerly National Committee for Clinical Laboratory Standards) broth microdilution assay, quality control (QC) MIC limits have not been established for any mold-agent combination. This multicenter (eight-center) study documented the reproducibility of tests for one isolate of Paecilomyces variotii ATCC MYA-3630 and 11 other mold isolates (three isolates of Aspergillus fumigatus; two isolates of A. terreus; one isolate each of A. flavus, A. nidulans, Fusarium moniliforme, and F. solani; and two isolates of Scedosporium apiospermum) by the CLSI reference broth microdilution method (M 38-A document). Control limits (amphotericin B, 1 to 4 microg/ml; itraconazole, 0.06 to 0.5 microg/ml; posaconazole, 0.03 to 0.25 microg/ml; voriconazole, 0.015 to 0.12 microg/ml) for the selected QC P. variotii ATCC MYA-3630 were established by the analysis of replicate MIC results. Reference isolates and corresponding MIC ranges were also established for 6 of the 12 molds evaluated. MIC limits were not proposed for the other five molds tested due to low testing reproducibility for these isolates.