C-215. A Multi-Site Evaluation of Caspofungin (CAS) on Sensititre® YeastOne® Susceptibility System Compared with the CLSI M27 Reference Broth Micro Dilution (BMD) Plate for Antifungal Susceptibility Testing

N. M. Holliday1, C. C. Knapp1, S. B. Killian1, C. M. Bastulli1, M. A. Ghannoum2, M. A. Pfaller3, S. A. Messer3, D. Diekema3, R. Ramani4, V. Chaturvedi4;
1TREK Diagnostic Systems, Cleveland, OH, 2Case Western Reserve Univ., Cleveland, OH, 3Univ. of Iowa Coll. of Med., Iowa City, IA, 4New York State Dept. of Hlth., Albany, NY.

Background: Caspofungin (Merck & Co. Rahway, New Jersey) is an echinocandin that is currently approved for use in the treatment of fungal infections and invasive aspergillosis. A multi-site evaluation was undertaken to determine the performance of the Sensititre® YeastOne® susceptibility system (TREK Diagnostic Systems, Cleveland, OH) with Caspofungin (CAS) compared to the CLSI Broth Microdilution Method BMD. Materials and Methods: 300 clinical (100 per site) and 100 challenge strains along with 25 reproducibility isolates of Candida spp. were tested at 3 sites comparing the performance of CAS on the Sensititre YeastOne plate with CLSI BMD. The range tested for CAS was (0.008-16ug/ml). CLSI quality control (QC) organisms were tested daily and were within the CLSI expected QC ranges. Results: Clinical isolate comparisons of the Sensititre YeastOne plate to the CLSI BMD resulted in 100% essential agreement (EA) +/- 2 log2 dilutions. Challenge isolates resulted in 100% EA +/- 2 log2 dilutions. YeastOne modal reproducibility MICs +/- 2 fold dilutions between sites for CAS resulted in 97.3% agreement at 24 hours. Three individual site reproducibility MICs yielded results within +/- 2 fold dilutions for CAS (100%, 96% and 96%) respectively. All isolates were susceptible (<2) and resulted in 100% categorical agreement. Conclusions: This evaluation indicates that the Sensititre YeastOne plate with CAS is equivalent to the CLSI BMD and is a potential method for susceptibility testing of CAS.