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Updated: May 11, 2026

Broth Microdilution In Vitro Screening: An Easy and Fast Method to Detect New Antifungal Compounds
Published on: February 14, 2018
Multicenter study of isavuconazole MIC distributions and epidemiological cutoff values for Aspergillus spp. for the
A Espinel-Ingroff1, A Chowdhary, G M Gonzalez
1VCU Medical Center, Richmond, Virginia, USA. avingrof@vcu.edu
Abstract:
Epidemiological cutoff values (ECVs) were established for the new triazole isavuconazole and Aspergillus species wild-type (WT) MIC distributions (organisms in a species-drug combination with no detectable acquired resistance mechanisms) that were defined with 855 Aspergillus fumigatus, 444 A. flavus, 106 A. nidulans, 207 A. niger, 384 A. terreus, and 75 A. versicolor species complex isolates; 22 Aspergillus section Usti isolates were also included. CLSI broth microdilution MIC data gathered in Europe, India, Mexico, and the United States were aggregated to statistically define ECVs. ECVs were 1 μg/ml for the A. fumigatus species complex, 1 μg/ml for the A. flavus species complex, 0.25 μg/ml for the A. nidulans species complex, 4 μg/ml for the A. niger species complex, 1 μg/ml for the A. terreus species complex, and 1 μg/ml for the A. versicolor species complex; due to the small number of isolates, an ECV was not proposed for Aspergillus section Usti. These ECVs may aid in detecting non-WT isolates with reduced susceptibility to isavuconazole due to cyp51A (an A. fumigatus species complex resistance mechanism among the triazoles) or other mutations.

