title: Wild-type MIC distributions and epidemiological cutoff values for amphotericin B and Aspergillus spp. for the CLSI broth microdilution method (M38-A2 document).
abstract: Although clinical breakpoints have not been established for mold testing, epidemiological cutoff values (ECVs) are available for Aspergillus spp. versus the triazoles and caspofungin. Wild-type (WT) MIC distributions (organisms in a species-drug combination with no acquired resistance mechanisms) were defined in order to establish ECVs for six Aspergillus spp. and amphotericin B. Two sets (CLSI/EUCAST broth microdilution) of available MICs were evaluated: those for A. fumigatus (3,988/833), A. flavus (793/194), A. nidulans (184/69), A. niger (673/140), A. terreus (545/266), and A. versicolor (135/22). Three sets of data were analyzed: (i) CLSI data gathered in eight independent laboratories in Canada, Europe, and the United States; (ii) EUCAST data from a single laboratory; and (iii) the combined CLSI and EUCAST data. ECVs, expressed in μg/ml, that captured 95%, 97.5%, and 99% of the modeled wild-type population (CLSI and combined data) were as follows: for A. fumigatus, 2, 2, and 4; for A. flavus, 2, 4, and 4; for A. nidulans, 4, 4, and 4; for A. niger, 2, 2, and 2; for A. terreus, 4, 4, and 8; and for A. versicolor, 2, 2, and 2. Similar to the case for the triazoles and caspofungin, amphotericin B ECVs may aid in the detection of strains with acquired mechanisms of resistance to this agent.
authors.affiliation: VCU Medical Center, Richmond, Virginia, USA. avingrof@verizon.net
authors.forename: A
authors.initials: A
authors.lastname: Espinel-Ingroff
authors.forename: M
authors.initials: M
authors.lastname: Cuenca-Estrella
authors.forename: A
authors.initials: A
authors.lastname: Fothergill
authors.forename: J
authors.initials: J
authors.lastname: Fuller
authors.forename: M
authors.initials: M
authors.lastname: Ghannoum
authors.forename: E
authors.initials: E
authors.lastname: Johnson
authors.forename: T
authors.initials: T
authors.lastname: Pelaez
authors.forename: M A
authors.initials: MA
authors.lastname: Pfaller
authors.forename: J
authors.initials: J
authors.lastname: Turnidge
mesh_terms: D000666:Amphotericin B / Q000494:pharmacology*; D001230:Aspergillus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests
chemical_list: D000666:Amphotericin B