title: Comparative and collaborative evaluation of standardization of antifungal susceptibility testing for filamentous fungi.
abstract: The purpose of the study was to evaluate the interlaboratory agreement of broth dilution susceptibility methods for five species of conidium-forming (size range, 2 to 7 microns) filamentous fungi. The methods used included both macro- and microdilution methods that were adaptations of the proposed reference method of the National Committee for Clinical Laboratory Standards for yeasts (m27-P). The MICs of amphotericin B, fluconazole, itraconazole, miconazole, and ketoconazole were determined in six centers by both macro- and microdilution tests for 25 isolates of Aspergillus flavus, Aspergillus fumigatus, Pseudallescheria boydii, Rhizopus arrhizus, and Sporothrix schenckii. All isolates produced clearly detectable growth within 1 to 4 days at 35 degrees C in the RPMI 1640 medium. Colony counts of 0.4 x 10(6) to 3.3 x 10(6) CFU/ml (mean, 1.4 x 10(6) CFU/ml) were demonstrated in 90% of the 148 inoculum preparations. Overall, good intralaboratory agreement was demonstrated with amphotericin B, fluconazole, and ketoconazole MICs (90 to 97%). The agreement was lower with itraconazole MICs (59 to 79% median). Interlaboratory reproducibility demonstrated similar results: 90 to 100% agreement with amphotericin B, fluconazole, miconazole, and ketoconazole MICs and 59 to 91% with itraconazole MICs. Among the species tested, the MICs for S. schenckii showed the highest variability. The results of the study imply that it may be possible to develop a reference method for antifungal susceptibility testing of filamentous fungi.
authors.affiliation: Medical College of Virginia/Virginia Commonwealth University, Richmond, USA.
authors.forename: A
authors.initials: A
authors.lastname: Espinel-Ingroff
authors.forename: K
authors.initials: K
authors.lastname: Dawson
authors.forename: M
authors.initials: M
authors.lastname: Pfaller
authors.forename: E
authors.initials: E
authors.lastname: Anaissie
authors.forename: B
authors.initials: B
authors.lastname: Breslin
authors.forename: D
authors.initials: D
authors.lastname: Dixon
authors.forename: A
authors.initials: A
authors.lastname: Fothergill
authors.forename: V
authors.initials: V
authors.lastname: Paetznick
authors.forename: J
authors.initials: J
authors.lastname: Peter
authors.forename: M
authors.initials: M
authors.lastname: Rinaldi
mesh_terms: D001230:Aspergillus / Q000187:drug effects; D005658:Fungi / Q000187:drug effects*; D008826:Microbial Sensitivity Tests / Q000592:standards*; D011541:Pseudallescheria / Q000187:drug effects; D012233:Rhizopus / Q000187:drug effects; D013053:Spectrophotometry