Black fungi: a survey of dematiaceous hyphomycetes from clinical specimens identified over a five year period in a reference laboratory.

Five hundred and fifty six dematiaceous hyphomycetes, the great majority referred from other laboratories, were identified by us over a five year period. Of these, thirty five were regarded as being of probable pathogenetic significance. These included seven isolates associated with chromoblastomycosis, and seven isolates thought to be causing phaeohyphomycosis. There were six strains of Phaeoannellomyces werneckii and five strains of Sporothrix schenckii. Seven isolates, all strains of Aureobasidium pullulans, were associated with fungal peritonitis in patients on chronic ambulatory peritoneal dialysis. Two Bipolaris isolates were associated with paranasal sinus fungus ball, a condition in which no evidence of tissue invasion by fungi could be found, even though pressure necrosis of bone could lead to very serious consequences. A further seven dematiaceous hyphomycetes, isolated from cases of paranasal fungus ball, keratitis and otitis externa, were thought to be of possible pathogenetic significance. Of the remaining 514 isolates thought to be of no pathogenetic significance, two thirds were made up of strains of Aureobasidium pullulans, Alternaria alternata, Cladosporium cladosporioides, Epicoccum purpurascens and Phoma species. In many cases it was thought that the referring laboratories had allowed insufficient time for development of conidiogenesis in these strains, before sending them to our laboratory for identification.