Interaction of the echinocandin caspofungin with amphotericin B or voriconazole against Aspergillus biofilms in vitro.

Aspergillus biofilms were prepared from 22 strains of Aspergillus spp. via a 96-well plate-based method. Using a broth microdilution checkerboard technique with the XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] colorimetric assay, we demonstrated a synergistic antifungal activity against 18 of 22 Aspergillus biofilm strains with a combination of caspofungin and amphotericin B and against 13 of 22 strains with a combination of caspofungin and voriconazole. We did not observe antagonism.