Pfaller M A, Barry A L
Department of Pathology, University of Iowa College of Medicine, Iowa City 52242.
J Clin Microbiol. 1994 Aug;32(8):1992-6. doi: 10.1128/jcm.32.8.1992-1996.1994.
A comparative evaluation of two broth microdilution methods for antifungal susceptibility testing of 600 clinical yeast isolates (Candida spp., Torulopsis glabrata, and Cryptococcus neoformans) against amphotericin B, fluconazole, and flucytosine (5FC) was conducted. Microdilution testing was performed according to National Committee for Clinical Laboratory Standards (NCCLS) recommendations (NCCLS document M27-P). By using the growth control for comparison, reference microdilution MIC endpoints for amphotericin B were scored as the lowest concentration at which a score of 0 (complete absence of growth) was observed, and those for 5FC and fluconazole were scored at the lowest concentration at which a score of 2 (prominent decrease in turbidity) (MIC-2) was observed. The second microdilution method employed a colorimetric endpoint using an oxidation-reduction indicator (Alamar Biosciences, Inc., Sacramento, Calif.) and was assessed independently of the reference microdilution MICs. The MICs for the two microdilution test systems were read after 24 and 48 h of incubation. Excellent agreement between the reference and colorimetric microdilution MICs was observed. Overall agreement was > or = 95% for all three drugs at 24 h. At 48 h, agreement was > or = 98% for amphotericin B and 5FC but dropped to 84% for fluconazole. Given these results it appears that the colorimetric microdilution approach to antifungal susceptibility testing may be viable alternative to the NCCLS reference method for testing yeasts.
对600株临床酵母分离株（念珠菌属、光滑球拟酵母菌和新型隐球菌）针对两性霉素B、氟康唑和氟胞嘧啶（5FC）进行抗真菌药敏试验的两种肉汤微量稀释法进行了比较评估。微量稀释试验按照美国国家临床实验室标准委员会（NCCLS）的建议（NCCLS文件M27 - P）进行。通过使用生长对照进行比较，两性霉素B的参考微量稀释MIC终点被记为观察到评分为0（完全无生长）的最低浓度，而5FC和氟康唑的参考微量稀释MIC终点被记为观察到评分为2（浊度显著降低）（MIC - 2）的最低浓度。第二种微量稀释法采用了使用氧化还原指示剂的比色终点法（Alamar Biosciences公司，加利福尼亚州萨克拉门托），并且独立于参考微量稀释MIC进行评估。两种微量稀释测试系统的MIC在孵育24小时和48小时后读取。观察到参考微量稀释和比色微量稀释MIC之间具有极好的一致性。在24小时时，所有三种药物的总体一致性≥95%。在48小时时，两性霉素B和5FC的一致性≥98%，但氟康唑的一致性降至84%。基于这些结果，看来用于抗真菌药敏试验的比色微量稀释方法可能是替代NCCLS参考方法用于酵母测试的可行方法。
