The Parasitic Phase of the Fungi of Chromoblastomycosis: Development of Sclerotic Cells in vitro and in vivo

Abstract

Using 19 isolates from chromoblastomycosis, representing the 4 varieties of the species Fonsecaea pedrosoi the species F. compacta, Phialophora verrucosa, and Torula bergeri, and also one isolate each of the saprophytic species Pleurage curvula, P. zygospora and two of Cladosporium spp., attempts were made to induce in vitro and in vivo the parasitic - "sclerotic-cell" - type of morphology. Three culture media were tested: a "synthetic lymph" imitating the composition of human cutaneous tissue fluids; the triple-peptone medium of Salvin; and Francis'' glucose-cystine blood agar. Partial induction of sclerotic cells was obtained with various isolates on the first 2 media; on the third, almost complete conversion to the parasitic type of growth was obtained with one isolate of P. verrucosa. The experiments in vivo made use of the chick chorioallantois, the pupae of 2 species of silkworm (Platysamia cecropia and Philosamia cynthia), and young albino mice. Conversion from the filamentous to the parasitic type of morphology was obtained in varying degree, depending on the isolate as well as conditions of culture: one isolate converted best on the chick embryo; another on mice. Conversion in all cases took place by formation by chlamydospores which gradually increased in numbers, became independent from the filamentous mycelium, and eventually replaced it.