Background: Exophiala is the main genus of black fungi comprising numerous opportunistic species. Data on antifungal susceptibility of Exophiala isolates are limited, while infections are potentially fatal.
Materials and methods: In vitro activities of eight antifungal drugs (AMB, five azoles, two echinocandins) against 126 clinical (n = 76) and environmental (n = 47) isolates from around the world were investigated. E. oligosperma (n = 58), E. spinifera (n = 33), E. jeanselmei (n = 14) and E. xenobiotica (n = 21) were included in our dataset.
Results: The resulting MIC90 s of all strains were as follows, in increasing order: posaconazole 0.063 μg/ml, itraconazole 0.125 μg/ml, voriconazole and amphotericin B 1 μg/ml, isavuconazole 2 μg/ml, micafungin and caspofungin 4 μg/ml, and fluconazole 64 μg/ml. Posaconazole, itraconazole and micafungin were the drugs with the best overall activity against Exophiala species. Fluconazole could not be considered as a treatment choice. No significant difference could be found among antifungal drug activities between these four species, neither in clinical nor in environmental isolates.
Conclusion: Antifungal susceptibility data for Exophiala spp. are crucial to improve the management of this occasionally fatal infection and the outcome of its treatment.
Keywords: Exophiala spp.; antifungal susceptibility; black yeast; posaconazole.
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