Multicenter evaluation of a broth macrodilution antifungal susceptibility test for yeasts

作者：Robert A. Fromtling, J N Galgiani, Michael A. Pfaller, Ana Espinel‐Ingroff, Ken F. Bartizal, Marilyn S. Bartlett, Barbara A. Body, Claudia Frey, Gerri S. Hall, Glenn D. Roberts · 发表于：Antimicrobial Agents and Chemotherapy · 年份：1993 · DOI：10.1128/aac.37.1.39 · 被引用次数：198 · 研究领域：Mycotoxins in Agriculture and Food、Antifungal resistance and susceptibility、Agricultural safety and regulations

Thirteen laboratories collaborated to optimize interlaboratory agreement of results of a broth macrodilution procedure for testing three classes of antifungal drugs against pathogenic yeasts. The activities of amphotericin B, flucytosine, and ketoconazole were tested against 100 coded isolates of Candida albicans, Candida tropicalis, Candida parapsilosis, Candida lusitaniae, Torulopsis (Candida) glabrata, and Cryptococcus neoformans. Two starting yeast inoculum sizes (5 x 10(4) and 2.5 x 10(3) cells per ml) were compared, and readings were taken after 24 and 48 h of incubation. All other test conditions were standardized. The resultant turbidities in all tubes were estimated visually on a scale from 0 to 4+ turbidity, and MIC-0, MIC-1, and MIC-2 were defined as the lowest drug concentrations that reduced growth to 0, 1+, or 2+ turbidity, respectively. For flucytosine, agreement among laboratories varied between 57 and 87% for different inocula, times of incubation, and end point criteria. Agreement was maximized (85%) when the lower inoculum was incubated for 2 days and the MICs were defined as 1+ turbidity or less. For amphotericin B, variations in test conditions produced much smaller differences in interlaboratory agreement. For ketoconazole, interlaboratory agreement was poorer by all end point criteria. However, MIC-2 endpoints distinguished T. glabrata as resistant compared with the other species. Overall, the studies indicated that readings from the lower inoculum obta...