Multisite reproducibility of MIC results by the Sensititre ® YeaStone Colorimetric Antifungal Susceptibility Panel

Abstract

Reproducibility of MIC results between laboratories, a major performance criterion used for evaluation of any susceptibility test method, was determined at three test sites using the Sensititre ® YeastOne Antifungal Panel, which incorporates Alamar Blue TM as a colorimetric indicator. MICs of five antifungals were determined using a set of 10 isolates of Candida species. Each isolate was tested a total of nine times against each antifungal agent in each of the three laboratories. A total of 1350 MICs were evaluated. MICs were read visually after incubation at 35°C for 24 and 48 h. Overall, 99 to 100% of MIC values were encompassed by a range defined by the modal MIC ± 1 dilution for each antifungal agent tested at both 24 h and 48 h. Replicate testing of the quality control isolates recommended by the National Committee for Clinical Laboratory Standards demonstrated excellent agreement between results obtained with the Sensititre ® YeastOne panel and the MIC reference range for each antifungal agent. These studies demonstrated that the Sensititre ® YeastOne Antifungal Panel may be used to generate MIC values for at least five different antifungal agents with a high degree of intra- and interlaboratory reproducibility.