Susceptibility of Aspergillus strains from culture collections to amphotericin B and itraconazole.

Susceptibility testing of 27 Aspergillus reference strains belonging to five species was performed using the microdilution broth method with yeast nitrogen broth and RPMI-1640. Similar results were found using the two media. The strains of Aspergillus fumigatus (n = 8) and Aspergillus niger (n = 4) had MICs of amphotericin B in the range 0.125-0.5 mg/L. In contrast, nine out of 13 strains of Aspergillus flavus and Aspergillus nidulans had MICs in the range 2-16 mg/L. All strains had MICs of itraconazole in the range 0.03-0.5 mg/L. It is concluded that both media can be used for testing. Susceptibility testing to amphotericin B is recommended in clinical settings.