[Emerging deep-seated fungal infection, trichosporonosis]

Deep-seated trichosporonosis is a lethal opportunistic infection occasionally found in immunocompromised patients, particularly those who are neutropenic due to cytotoxic therapy for hematological malignancies. Trichosporon asahii is considered the principal etiologic agent of non-Candida fungemia and disseminated trichosporonosis in Japan. This infection may disseminate to multiple organs and difficult to diagnosis and treat. Because clinical findings and courses of trichosporonosis are similar to disseminated candidasis, it is impossible to distinguish these infections without fungal isolation. Monotherapy of amphotericin B is thought to be unsuccessful for this infection, and new antifungal agents echinocandins are also not active against Trichosporon species. Some clinical reports and animal models suggest that triazoles and combination therapies are most effective drugs against trichosporonosis. Recently, T. asahii isolates with reduced susceptibility in vitro to multi-antifungal agents are reported. T. asahii is the allergen of summer-type hypersensitivity pneumonitis and sometimes isolated from the houses environments, but it is not clear that the environmental strains directly infect to human. There is no clinical evidence that Trichosporon is the common outbreak pathogen in the hospital. However, it is necessary for a clinician to pay enough care as the lethal infections in immunocompromised patients.