Pharmacotherapy of Candida Infections with Echinocandins

Comparison of micafungin MICs as determined by the Clinical and Laboratory Standards Institute broth microdilution method (M27-A3 document) and Etest for Candida spp. isolates

Micafungin Etest and Clinical and Laboratory Standards Institute (CLSI) MICs were compared for 337 Candida spp. isolates. The performance of Etest for testing the susceptibilities of Candida spp. to micafungin was evaluated by the assessment of both categorical (CA) and essential (EA) agreements. The CA was evaluated 2 ways: (i) by the ability of Etest to separate resistant (nontreatable) from susceptible (treatable) isolates by using the newly adjusted species-specific micafungin clinical breakpoints (CBPs) that are available for most of the common species tested and (ii) by the ability to separate wild type (WT) from non-WT isolates or those harboring FKS mutations (with reduced echinocandin susceptibility) by using micafungin epidemiologic cutoff values (ECVs). Etest and CLSI MICs were in EA when the MICs were within 2 log(2) dilutions. Based on agreement percentages, our data indicated that Etest is suitable to test micafungin for most of the Candida species evaluated (overall EA 94.7%; overall CA according to CBPs 97.2% and according to ECVs 97.3%). However, the number of resistant isolates was small, so further evaluations are needed with a higher number of such isolates including more resistant or those with known mechanisms of resistance (non-WT).

In vitro activity of echinocandins against non-Candida albicans: is echinocandin antifungal activity the same?

The echinocandins anidulafungin, caspofungin, and micafungin have a broad and similar spectrum of in vitro and in vivo activity against most Candida spp. Minimal inhibitory concentrations (MICs) for Candida spp. are usually below 1 μg/mL for most isolates. The exceptions are Candidaparapsilosis and C. guilliermondii. Species-specific clinical breakpoints (CBPs) and epidemiologic cutoff values (ECVs) have been proposed by the Clinical and Laboratory Standards Institute (CLSI) for the eight most common Candida spp. versus each echinocandin; these values are useful to detect in vitro antifungal resistance (CBPs) and to identify isolates harboring fks mutations or having reduced susceptibility (ECVs). This paper presents a review of the literature (2006-2010) regarding the in vitro activity similarities or differences among the three echinocandins against Candida spp.; different parameters or measurements of in vitro potency were evaluated. The focus of the review is the non-Candida albicans species.