Comparison of Eucast and CLSI Broth Microdilution Methods for the Susceptibility Testing of 10 Systemically Active Antifungal Agents against Candida spp

M. A. Pfaller, S. A. Messer, R. N. Jones, M. Castanheira

Abstract: 

Background: The need for reproducible, clinically relevant antifungal susceptibility testing of Candida spp. has been promoted by the increasing number of infections, the expanding use of new and established antifungal agents, and recognition of antifungal resistance or mechanism as an important clinical problem. Currently, there are two independent standards for clinical susceptibility testing of Candida: the Clinical and Laboratory Standards Institute (CLSI) method and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) method. These methods have been harmonized so that there is a close agreement between MIC results obtained when testing fluconazole (FLC) against Candida.
Methods: due to the international importance of these two methods for surveillance of antifungal resistance there is a need to continue the process of harmonization for the testing of other new and established antifungal agents. The present study examines the essential agreement (EA; ± log2 dilutions) between the methods for testing 10 antifungal agents (amphotericin B, 5-flucytosine [5FC], anidulafungin [ANF], caspofungin [CSF], micafungin [MCF], FLC, itraconazole, posaconazole [PSC], voriconazole [VRC], and Isavuconazole [ISA]) against a collection of 468 clinical isolates of Candida spp.
Results: C. albicans (CA; 156 isolates), C. glabrata (CG, 98 isolates), C. parapsilosis (CP, 98 isolates), C. tropicalis (CT, 74 isolates) and C. krusei (CK, 42 isolates) were concurrently tested by both methods. Excellent EA between CLSI and EUCAST MIC results was observed. The overall EA between EUCAST and CLSI results ranged from 81.2% [ANF] to 99.6% [5FC]. The EA was >90% for 5FC (99.6%), CSF (96.4%), MCF (98.8%), FLC (99.2%), VRC (98.9%) and ISA (93.1%).
Conclusions: These results suggest that the CLSI and EUCAST methods provide comparable results for a wide range of antifungal agents and may be used effectively in resistance surveillance and clinical testing of the five most common species of Candida.

abstract No: 

M-1349
    • ICAAC 53rd (2013)