Eucast Definitive Document

Antifungal susceptibility tests are performed on fungi that cause disease, especially if they belong to a species exhibiting resistance to commonly used antifungal agents. Antifungal susceptibility testing is also important for resistance surveillance, for epidemiological studies and for comparing the in-vitro activity of new and existing agents. Dilution methods are used to establish the MICs of antimicrobial agents. These are the reference methods for antimicrobial susceptibility testing, and are used mainly to establish the activity of a new antifungal agent, to confirm the susceptibility of organisms that give equivocal results in routine tests, and to determine the susceptibility of fungi where routine dilution tests may be unreliable. Fungi are tested for their ability to produce visible growth in microdilution plate wells containing broth culture media and serial dilutions of the antifungal agents (broth microdilution). The MIC is defined as the lowest concentration (in mg ⁄L) of an antifungal agent that inhibits the growth of a fungus. The MIC provides information concerning the susceptibility or resistance of an organism to the antifungal agent and can help in making correct treatment decisions. The method described in this document is intended for testing the susceptibility of yeasts that cause clinically significant infections (primarily Candida spp.). The method encompasses only those yeasts that are able to ferment glucose. Thus, the susceptibility of non-fermentative yeasts, e.g., Cryptococcus neoformans, cannot be determined by the current procedure, and the method is not suitable for testing the yeast forms of dimorphic fungi.