Fusariosis, a complex infection caused by a high diversity of fungal species refractory to treatment.

In recent years the number of opportunistic invasive fusariosis has increased significantly, the main factors involved in these infections being reviewed here. In spite of the extensive literature published the advances in the management of disseminated fusariosis have been very poor and it remains a severe infection, refractory to treatment and with a high mortality rate. There are no ideal therapies and the presence of neutropenia has a critical part to play in the outcome of the infection. At least 70 species have been involved in fusariosis. Fusarium solani species complex is responsible for nearly 60% of the cases and F. oxysporum species complex for approximately 20% of them. Most of the infections are caused by four species, i.e. F. petroliphilum, F. keratoplasticum and other two unnamed phylogenetic species. The efficacy of amphotericin B and voriconazole, the most used antifungal drugs, for treating invasive fusariosis are controversial but in general the percentage of patients cured in the different clinical trials is low. Infections by Fusarium verticillioides seem to have the best prognosis. The recent release of complete genome sequences of the most clinically relevant species and the emergence of fungal genomics offer excellent opportunities for examining the multifactorial processes of Fusarium pathogenicity. Using knockout mutants of genes encoding sequence-specific proteins, several virulence factors have been characterized.