In-vitro activities of voriconazole, itraconazole and Amphotericin B against Aspergillus species

In vitro susceptibility testing for filamentous fungi is under development. Using the broth macrodilution method, we compared the in vitro activities of Voriconazole (VCZ), Itraconazole (ITZ) and Amphotericin B (AB) against 216 clinical isolates of Aspergillus spp. (142 isolates of A. fumigatus and 74 of non-fumigatus Aspergillus spp.). 0.5 ml of PYG medium (1 g peptone, 1 g yeast extract and 3 g dextrose per liter distilled water) with various concentrations of the antifungal drug and 0.5 ml conidial suspension (1 × 10⁴ cfu/ml) was incubated at 37 °C for 48 h and MIC endpoints were read visually. The MIC in micrograms/ml (mean+/-SD, range) for A. fumigatus were as follows: VCZ 0.88+/-0.54,0.25-4; ITZ 0.54+/-0.46,0.25-4; AB 2.16+/-1.64, 0.5-8. MIC₉₀ were as follows: VCZ 2, ITZ 1, AB 4. MICs for non-fumigatus Aspergillus spp. were: VCZ 1.57+/-1.17, 0.25-4; ITZ 1.74+/-1.63,0.25-4; AB 2.88+/-1.47,0.5-8. MIC₉₀ for this group were: VCZ 4, ITZ 4, AB 4.The mean MICs of azoles (VCZ and ITZ) were 2 3 times higher for the non-fumigatus Aspergillus spp. Our study shows that VCZ is as effective as ITZ and AB against Aspergillus (fumigatus and non-fumigatus spp.) in vitro and that non-fumigatus Aspergillus is less susceptible than A. fumigatus to the azole antifungals tested.