Michael R. McGinnis

Chromoblastomycosis and phaeohyphomycosis: New concepts, diagnosis, and mycology

The nomenclature for the mycoses caused by dematiaceous fungi should represent the combined clinical, pathologic, and mycologic relationships exhibited in the diseases. Chromoblastomycosis encompasses chronic, localized infections of the cutaneous and subcutaneous tissues that contain sclerotic bodies and histologically show hyperkeratotic pseudoepitheliomatous hyperplasia with keratolytic microabscess formation in the epidermis. In contrast, phaeohyphomycosis is a collective term for a heterogeneous group of mycotic infections that contain dematiaceous yeastlike cells, pseudohyphae-like elements, hyphae, or any combination of these forms in tissue. The terms superficial, cutaneous and corneal, subcutaneous, and systemic phaeohyphomycosis are proposed for the major categories of phaeohyphomycosis. The term chromomycosis is rejected for mycoses caused by the dematiaceous fungi.

Taxonomy of Exophiala werneckii and its relationship to Microsporum mansonii

Study of the neotype culture of Exophiala werneckii (Cladosporium werneckii), as well as additional isolates, has shown that the yeast-like and hyphal conidiogenous cells are annellides. E. werneckii cannot be accommodated in Cladosporium, a genus characterized by catenulate holoblastic coanidia. E. werneckii and the dematiaceous hyphomycete that Castellani misidentified as Microsporum mansonii (Cladosporium mansonii) are two entirely different fungi. M. mansonii is considered to be a synonym of the Malassezia furfur since both names were used to describe in tissue the etiologic agent of pityriasis versicolor.

Taxonomy of Exophiala jeanselmei (Langeron) McGinnis and Padhye

AbstractThe black yeast-like fungus Exophiala jeanselmei (Langeron) McGinnis et Padhye was originally described as Torula jeanselmei by Langeron. Since its original description in 1928, this dematiaceous hyphomycete has been placed in the genera Phialophora, Pullularia and Rhinocladiella by various authors. Study of the type culture of E. jeanselmei has confirmed that the principle conidiogenous cells of this fungus are annellides, thus supporting its current generic disposition.After reviewing the neotype culture of Phialophora gougerotii (Matruchot) Borelli sensu Borelli, the type culture of Torula bergeri Langeron, authentic cultures of Margarinomyces heteromorpha (Nannfeldt) Mangenot sensu Mangenot, the type culture of Trichosporium heteromorphum Nannfeldt and the neotype culture of Exophiala mansonii (Castellani) de Hoog sensu de Hoog, as well as additional cultures, it was concluded that P. gougerotii sensu Borelli, T. bergeri and M. heteromorpha sensu Mangenot pro parte are conspecific with E. jeanselmei.nTrichosporium heteromorphum and E. jeanselmei are not conspecific as suggested by some workers, Tr. heteromorphum is a distinct species and should be referred to as Phialophora heteromorpha (Nannfeldt) Wang. Sporotrichum gougerotii Matruchot is considered to be a later synonym of Sporothrix schenckii Hektoen et Perkins and E. mansonii sensu de Hoog as a later synonym of Microsporum mansonii Castellani. M. mansonii is held to be a later synonym of Malassezia furfur (Robin) Baillon. The neotype culture of E. mansonii produces phialides without collarettes.

Serodiagnosis of histoplasmosis, blastomycosis and coccidioidomycosis

Summary To make a serological diagnosis of histoplasmosis, blastomycosis or coccidioidomycosis, (a) obtain blood for serological studies prior to or soon after employing skin test antigens. (b) whenever possible, obtain both an acute and a convalescent serum specimen. (c) make sure that each specimen is tested against antigens prepared from each of the three dimorphic fungi. (d) do not rely exclusively upon the results of serological tests for diagnosis. There is no diagnostic test that can fully replace sound clinical judgment and cultural confirmation of the suspected etiological agent (2).