NOTES In Vitro Susceptibility of Clinical Isolates of Aspergillus spp. to Anidulafungin, Caspofungin, and Micafungin: a Head-to-Head Comparison Using the CLSI M38-A2 Broth

We determined the in vitro activities of anidulafungin, caspofungin, and micafungin against 526 isolates of Aspergillus spp. (64 A. flavus, 391 A. fumigatus, 46 A. niger, and 25 A. terreus isolates) collected from over 60 centers worldwide from 2001 through 2007. Susceptibility testing was performed according to the CLSI M38-A2 method. All three echinocandins—anidulafungin (50 % minimum effective concentration [MEC50], 0.007 g/ ml; MEC90, 0.015 g/ml), caspofungin (MEC50, 0.015 g/ml; MEC90, 0.03 g/ml), and micafungin (MEC50, 0.007 g/ml; MEC90, 0.015 g/ml)—were very active against Aspergillus spp. More than 99 % of all isolates were inhibited by <0.06 g/ml of all three agents. The echinocandins anidulafungin, caspofungin, and mica-fungin are a group of recently introduced systemically active antifungal agents that inhibit the (1,3)--D-glucan synthase activity of Candida and Aspergillus spp. (3, 7, 12). Although each of these agents has been studied clinically for treatment of invasive aspergillosis (IA) (5, 10) (Pfizer, Inc., unpublished dat