Development of a Peptide Nucleic Acid Probe to Trichosporon Species and Identification of Trichosporonosis by Use of In Situ Hybridization in Formalin-Fixed and Paraffin-Embedded (FFPE) Sections

In order to identify Trichosporon species in formalin-fixed and paraffin-embedded sections fromwhich visual discrimination of non-glabrata Candida species is mostly ineffective but critical for the choice of antifungals, we tested the usefulness of a newly designed peptide nucleic acid probe (PNA) for in situ hybridization (ISH). Results confirmed the usefulness of ISH with our PNA probe in identifying Trichosporon species from Candida albicans. Trichosporon species have been reported as the second or thirdmost common agents of yeast fungemia (1–3), and the preva-lence has increased, particularly in patients with hematologic malignancies (4–6). Since Trichosporon spp. exhibit low suscepti-bility to candins (7), histopathological examination is important as one of the useful diagnostic procedures, even though it is re-garded as poor for the identification of Trichosporon species from other dimorphic yeasts, namely, non-glabrata Candida, species, because of their overall similarities (8–10). Therefore, the estab-lishment of an auxiliary diagnostic method for use in routine pathological laboratories is required for diagnosis of disseminated trichosporonosis. In the present study, we report attempts to de