In vitro interactions of antifungal agents against Fusarium spp. clinical isolates

Abstract

The in vitro activities of amphotericinB(AMB), itraconazole (ITC), voriconazole (VCZ) and terbinafine (TBF) alone and in the combinationsAMB+ VCZ, TBF + ITC and TBF + VCZ were evaluated against 29 clinical isolates of Fusarium spp. (15 Fusarium solani, 7 Fusariumoxysporum, 2 Fusarium decemcellulare, 2 Fusarium dimerum and 3 other Fusarium spp.). Minimum inhibitory concentrations were determinedusing the method of the Clinical and Laboratory Standards Institute and the interaction activity was calculated using the fractional inhibitoryconcentration index. The four antifungal drugs tested alone showed very limited activity against most of the isolates. In contrast, the combinationTBF + VCZshowed synergy for 21 isolates. The combinationAMB+ VCZshowed synergism for only five strains.Nointeraction or antagonismwas observed among the remaining strains. TBF + ITC showed no interaction for 18 strains. The in vitro antifungal activity of the drugs aloneand in combination varied for different species. These results corroborate previous in vitro studies in which the combination TBF + VCZshowed synergy against Fusarium spp., although further studies are needed to elucidate its potential usefulness for therapy.