Method for the determination of minimum inhibitory concentration (MIC) by broth dilution of fermentative yeast

Dilution methods are used to determine the minimum inhibitory concentrations (MICs) of antimicrobial agents and are the reference methods for antimicrobial susceptibility testing. In dilution tests, microorganisms are tested for their ability to produce visible growth in microtitration plate wells of broth (broth microdilution) containing serial dilutions of the antimicrobial agents. The MIC is defined as the lowest concentration of an antimicrobial agent that inhibits the growth of a microorganism. The method described in this document is intended for testing yeasts that cause clinically significant infections (primarily Candida species). This standard encompasses only those yeasts that are able to ferment glucose. Thus, testing the susceptibility of nonfermentative yeasts such as Cryptococcus neoformans var. neoformans cannot be determined by the current procedure nor is the methodology suitable for the yeast forms of dimorphic fungi.