[Sporotrichosis and dematiaceous fungal skin infections].

Sporotrichosis is a chronic infectious granuloma of skin. The detection of fungal elements in pathological examination and the isolation of Sporothrix schenckii from the lesion are requisite for diagnosis. The sporotrichin test is useful as an auxiliary examination, but a false-negative reaction might occur in some cases. Oral potassium iodide is first choice of treatment, because of its modest cost and usefulness, although gastrointestinal disorder is a frequent side effect. Itraconazole should be the second selection, and then terbinafine. Local thermotherapy is also effective as an additional therapy. Dematiaceous fungal skin infections are divided into two groups by their parasitic form, chromoblastomycosis and phaeohyphomycosis. Chromoblastomycosis is also called chromomycosis in Japan. It is most important for clinical diagnosis to detect dark brown spores in the scale of chromoblastomycosis and dark brown hyphae in the pus of phaeohyphomycosis by microscopic examination. Both morphological and molecular biological approaches are recommended for identification of fungi. In treatment, the drug appropriate in each case should be selected, and the combination of surgical excision, local thermotherapy, laser therapy or cryotherapy must be considered.

Effects of hyperthermia on phagocytosis and intracellular killing of Sporothrix schenckii by polymorphonuclear leukocytes.

The effects of hyperthermia on phagocytosis and killing of Sporothrix schenckii by polymorphonuclear leukocytes (PMNs) were investigated in order to clarify the mechanism of local thermotherapy for sporotrichosis. Yeast cells of S. schenckii, PMNs and serum were incubated at 37 degrees C or 40 degrees C for 2 or 4 hours. Rate of phagocytosis and killing rate (rate of germination) were estimated, and their processes were observed by transmission electron microscopy. There was no effect of hyperthermia on the phagocytosis rate, but the killing rate increased significantly at 40 degrees C. Electron microscopic examination showed an increase of granularity in the yeast cytoplasm, elongation and fragmentation of the cell membrane. The ultrastructural changes were basically identical under both temperatures, but the degree of these changes was higher at 40 degrees C than at 37 degrees C. Although both intact and degenerated yeasts were found in the same conditions, their transient forms were few, suggesting that the PMN-killing process was completed promptly.

The effects of heat on Sporothrix schenckii in vitro and in vivo.

In order to clarify the mechanism of action of topical thermotherapy on sporotrichosis, the effects of heat on Sporothrix schenckii in vitro and in vivo were investigated by observing the percentage germination and the ultrastructure. When the spores were heated to 42 degrees C, it took 10 hr with the conidia, 2 hr with the yeast-like cells and 1 hr with the spores in vivo to reduce the germination rates to 10%. The percentage germination curves were reduced slowly at first but later exponentially. Changes in the ultrastructure became evident in 2 hr with the yeast-like cells and in 8 hr with the conidia. The ribosome count declined and amorphous dense materials appeared in the cytoplasm and mitochondria. In vivo, the outstanding feature of the heated spores was the diversity of internal ultrastructural changes encountered and morphological changes. These were observed at 1 hr post treatment.