New Fusarium species causing fungal rhinosinusitis
May 21 2018
Most of the 73 species of Fusarium that have been isolated from human infections belong to the Fusarium solani species complex (FSSC). Invasive fungal rhinosinusitis (FRS) is a particularly rare manifestation seen among some patients with haematological malignancies. Mortality rates are high and there is currently no consensus on treatment timing.
Dr Dallé Rosa and colleagues in Brazil and the Netherlands recently described a new species of Fusarium associated with a case of FRS. An 11-year-old boy presented with a 2-week history of fever, bilateral nasal obstruction and watering from the eyes and nose. Three years earlier he had been diagnosed with acute lymphoblastic leukaemia and had received chemotherapy, and he was neutropenic at presentation (300/mm3). A black-crusted lesion was found inside the nasal fossa which showed the presence of invading hyphae.
Cultures grown on Sabouraud dextrose agar produced curved conidiophores and red pigment typical of Fusarium spp. Multi-locus sequence typing (ITS-LSU, RPB2, TEF-1α) situated the isolate closest to NRRL strain 22178, but all sequences showed >1% similarity, showing that this was indeed a new species.
Antifungal susceptibility was comparable to related species: low to first-generation triazoles, but better towards second-generation triazoles and amphotericin B. In this case, induction treatment with IV voriconazole followed by consolidation with oral voriconazole was successful.
Fusarium riograndense macroconidia (3-6 segments) and microconidia (1-2 segments) stained with lactophenol cotton blue.