Multicenter comparison of a colorimetric microdilution broth method with the reference macrodilution method for in vitro susceptibility testing of yeast isolates.
This multicenter study was performed to compare a colorimetric microdilution method with the NCCLS M27-P reference macrodilution method for the testing of yeast isolates against amphotericin B, fluconazole, and 5-fluorocytosine (5FC). Testing was performed on ten yeast isolates in five independent laboratories. All sites tested each isolate a total of 20 times with both methods. MICs were read after 48 h incubation. The macrodilution MIC reference range was defined as the modal MIC +/- 1-log2 dilution for each organism-antifungal agent combination. Agreement between the M27-P reference range results and the microdilution MICs was 86% with amphotericin B, 90% with fluconazole, and 93% with 5FC. Based on these data, it is apparent that new approaches, such as the colorimetric microdilution method, will provide MIC values comparable to the M27-P macrodilution method in a format that is more practical for use in a busy clinical laboratory.
University of Iowa College of Medicine, Iowa City 52242.
M A
MA
Pfaller
B
B
Buschelman
M J
MJ
Bale
M
M
Lancaster
A
A
Espinel-Ingroff
J H
JH
Rex
M G
MG
Rinaldi
D000666:Amphotericin B / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial / Q000379:methods / Q000592:standards*; D003124:Colorimetry; D015725:Fluconazole / Q000494:pharmacology; D005437:Flucytosine / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards*; D012015:Reference Standards; D012016:Reference Values; D015003:Yeasts / Q000187:drug effects*
D000935:Antifungal Agents; D000666:Amphotericin B; D015725:Fluconazole; D005437:Flucytosine