Specific antifungal susceptibility profiles of opportunists in the Fusarium fujikuroi complex

The aim of the present study was to evaluate and assess the in vitro activity of eight drugs, including the new azole isavuconazole, against 81 strains representing 13 species of the Fusarium fujikuroi species complex. A total of 81 Fusarium spp. isolates, within the F. fujikuroi species complex, were identified by molecular methods and tested according to CLSI M38-A2. Eight antifungal compounds, including the new azole isavuconazole, were tested. Isolates were selected to represent the widest variety of geographical regions and to include clinical as well as environmental strains. Susceptibility profiles differed between and within species, with Fusarium verticillioides showing the lowest MICs and Fusarium nygamai the highest MICs. Amphotericin B was the most active drug, followed by voriconazole, posaconazole, isavuconazole and natamycin. The remaining antifungals (fluconazole, itraconazole and micafungin) showed poor activity with MIC/minimum effective concentration values of ≥ 32, ≥ 16 and >8 mg/L, respectively. Resistance patterns in the F. fujikuroi species complex are species specific and therefore identification down to species level is important for the choice of antifungal treatment.