[Study of in vitro activity of caspofungin on non-Candida albicans yeast strains determined by two methods: M27-A2...

The in vitro activity of caspofungin against 147 non-Candida albicans yeasts isolated from blood culture was studied using two broth microdilution methods: M27-A2 and EUCAST. The minimum concentrations that produced a growth inhibition of > or = 50% and of 100% (MIC2 and MIC0, respectively) and a reduction in the number of viable colonies > or = 99% versus the initial inoculum (MFC) were determined for all strains. Caspofungin demonstrated good activity (MIC2 and MIC0 < or = 2 mg/l for 90% of the strains) against the species studied, including those that are normally resistant or have a high percentage of azole resistance (Candida krusei, Candida glabrata, Candida tropicalis). Nevertheless, the antifungal activity is lower (MFC < or = 2 mg/l in 73.47% of the strains with the M27-A2 method versus 62.59% with EUCAST), particularly for Candida guilliermondii and Candida parapsilosis. The two methods tested demonstrated good correlation for the MIC and lower correlation for the MFC. Essential agreement and concordance (+/- 2 log) between both methods for all strains tested were: 73.47% and 93.20% for MIC2; 74.8% and 91.84% for MIC0; and 57.1% and 74.15% for MFC, respectively. MICs determined by the EUCAST method are one- to three-fold dilutions lower, while the MFC are higher than those obtained by the M27-A2 method.