CLSI M51-P

CLSI broth dilution reference methods are available for susceptibility testing of filamentous fungi (see CLSI document M38)1and yeasts (see CLSI documents M27(2) and M44(3)). There still remains, however, a need for an alternative simple, rapid, and costeffectiveapproach to determine the susceptibility of nondermatophyte filamentous fungi (moulds) to various classes of antifungalagents that would make antifungal susceptibility testing more readily available to clinical microbiology laboratories. The CLSISubcommittee on Antifungal Susceptibility Testing developed a disk diffusion method for testing filamentous fungi toamphotericin B, caspofungin, itraconazole, posaconazole, and voriconazole.4 Although clinical breakpoints have not beenassigned, epidemiological cutoff values (ECVs) have been developed based on a comparison of zone diameters vs minimalinhibitory concentrations (MICs) or minimal effective concentrations (MECs) using the rate bounding method; controlparameters for these agents have also been determined.4 The ECVs are used to detect those isolates with reduced susceptibility tothe tested agent compared with the wild-type distribution. ECVs are not used as clinical breakpoints, but rather to detect thoseisolates that are likely to have acquired resistance mechanisms. One significant advantage of this method is that qualitative resultscan usually be determined after only 16 to 48 hours incubation as opposed to 24 to 72 hours with CLSI document M38.1 Thereare more antifungal agents and it is expected that this document will further encourage the development of disk diffusion testingfor some of these agents.

Published:

06/01/2009

ISBN(s):

1562387022

Number of Pages:

36