CLSI broth dilution reference methods are available for susceptibility testing of filamentous fungi (see CLSI document M38)1
and yeasts (see CLSI documents M27(2) and M44(3)). There still remains, however, a need for an alternative simple, rapid, and costeffective
approach to determine the susceptibility of nondermatophyte filamentous fungi (moulds) to various classes of antifungal
agents that would make antifungal susceptibility testing more readily available to clinical microbiology laboratories. The CLSI
Subcommittee on Antifungal Susceptibility Testing developed a disk diffusion method for testing filamentous fungi to
amphotericin B, caspofungin, itraconazole, posaconazole, and voriconazole.4 Although clinical breakpoints have not been
assigned, epidemiological cutoff values (ECVs) have been developed based on a comparison of zone diameters vs minimal
inhibitory concentrations (MICs) or minimal effective concentrations (MECs) using the rate bounding method; control
parameters for these agents have also been determined.4 The ECVs are used to detect those isolates with reduced susceptibility to
the tested agent compared with the wild-type distribution. ECVs are not used as clinical breakpoints, but rather to detect those
isolates that are likely to have acquired resistance mechanisms. One significant advantage of this method is that qualitative results
can usually be determined after only 16 to 48 hours incubation as opposed to 24 to 72 hours with CLSI document M38.1 There
are more antifungal agents and it is expected that this document will further encourage the development of disk diffusion testing
for some of these agents.
| ISBN(s) : | 1562387022 |
| Number of Pages : | 36 |
| Published : | 06/01/2009 |
