In vitro interactions of azoles and echinocandins against clinical strains of Aspergillus flavus

Combinations of an azole (itraconazole, voriconazole, or posaconazole) with an echinocandin (caspofungin, micafungin, or anidulafungin) were tested against 20 clinical isolates of Aspergillus flavus according to EUCAST guidelines. The interactions were determined using two endpoints-minimal effective concentration (MEC) and minimal inhibitory concentration (MIC)-via calculation of the fractional inhibitory concentration (FIC) index. A higher prevalence of synergistic interactions was observed for MIC, whereas indifference was the most frequent outcome according to MEC among the 20 strains. Combined treatment of A. flavus with these two important classes of antifungals should be explored further in in vivo studies.