Immunohistochemical identification of Trichosporon beigelii in histologic section by immunoperoxidase method.

An indirect immunoperoxidase method capable of identifying an opportunistic fungus, Trichosporon beigelii, in formalin-fixed, paraffin-embedded tissue has been developed. The authors studied autopsy materials from 19 patients with various fungal infections, including 3 patients with disseminated T. beigelii infection, 8 patients with localized or systemic candidiasis, 4 patients with invasive aspergillosis, 2 patients with pulmonary mucormycosis, and 2 patients with systemic cryptococcosis. T. beigelii could be successfully visualized in tissue sections from all three patients with this infection and a patient with systemic candidiasis who was found to have concomitant infection by T. beigelii. The capsule of Cryptococcus neoformans was also stained, indicating the presence of cross-reactive antigen between T. beigelii and C. neoformans. C. neoformans-absorbed antiserum was reactive with T. beigelii but not with other fungi, including C. neoformans.