Abstract: Objective To investigate the pathogenic factors and the visceral involvement in murine disseminated trichosporonosis caused by Trichosporon asahii. Methods Forty-five mice were immunosuppressed with cyclophospamide 3 days hefore and 7 days after inoculation of T. asahii, and were divided into intravenously inoculated group (n=15), intradermal inoculated group (n=7), gastrointestinal infusion group (n=8), intravenously inoculated + treatment group (n=15). In the control groups the mice were not immunosuppressed, and were also divided into intravenous, intradermal, and G.I. infusion groups with the same number of mice respectively. In the treatment group the mice were given both liposomal amphotericin B and fluconazole. The main viscera of the mice were examined by mycologic culture and pathologic sections. Results In the intravenous inoculation group of immunized mice, Trichosporon asahii were isolated from at least one organ in 10/12 mice, while T. asahii were only isolated in 2/14 mice in the control group; in 2/7 mice of the intradermal group of immunosuppressed mice, skin lesion appeared at the inoculation site, but no visceral infection was observed. No visceral infection was found in the groups that T. asahii was inoculated by non-intravenous injection in both immunosuppressed and non-immunosuppressed mice. The number of mice died, the number of visceral organs involved and the incidence of systemic infection were significantly less in the treatment group than those in the non-treatment groups (P<0.01). Histopathology showed acute pyogenous inflammation and granuloma with arthrospores and mycelia in the tissues. Conclusions Trichosporon asahii is an opportunistic pathogen which can lead to the infection of the skin or viscera in immunocompromized host. However, the immnocompetent host may be infected when there are enough Trichosporon asahii present. The most susceptible viscera are liver, lung, kidney, spleen and heart. The combination treatment of the liposomal amphotericin B and the fluconazole can inhibit the infection and dissemination.

Key words: Trichosporon, Trichosporonosis, Animal testing alternative