Fusarium riograndense sp. nov., a new species in the Fusarium solani species complex causing fungal rhinosinusitis

Summary Invasive fusariosis has a high mortality and is predominantly observed in patients with leukemia. We report the first case of a novel species of Fusarium , Fusarium riograndense sp. nov, isolated from a lesion in the nasal cavity lesion of a patient with acute lymphoblastic leukemia. The etiological agent was identified by Multilocus Sequencing Typing (MLST), including RPB2, TEF-1a, and ITS-LSU sequences, the gold standard technique to identify new species of Fusarium . MLST and phenotypic data strongly supported its inclusion in the F. solani species complex (FSSC). The new species produced a red pigment in the Sabouraud Dextrose Agar similar to other members of the complex. The macroconiodia developed from phialides on multibranched conidiophores which merge to form effuse sporodochia with a basal foot-cell instead of papilla in basal cell shape. The microconidia were ellipsoidal, 0–1-septated, produced from long monophialides. Chlamydospores were produced singly or in pairs. Amphotericin B (MIC 1 µg/mL) was the most active drug, followed by voriconazole (MIC 8 µg/mL). The patient was successfully treated with voriconazole. Our findings indicate another lineage within FSSC capable causing of invasive human infection.