Nigrospora Species

SEPTATE OPPORTUNISTS

Hyphae of most opportunists molds contain cross-walls. Those of medical importance fall into the phylum Deuteromycota. The septate opportunistic molds may be divided into those that are dematiaceous (dark-colored hyphae and/or conidia), and those that are hyaline (light colored hyphae and conidia). Organisms with dark hyphae on tease mounts also have dark green to black colonies, especially on the colony reverse. The colonial color aids in the initial identification. Hyaline organisms exhibit light-colored colonial aerial hyphae, but they may be covered over with brightly colored comidia; thus, a tease mount is required. In the following descriptions, key identifying features are capitalized.

DEMATIACEOUS OPPORTUNISTS

Opportunists with dark-colored hyphae may cause phaeohyphomycosis (infection caused by dematiaceous fungi).

PATHOGENICITY

Nigrospora has been reported as a causative agent of keratomycosis.

LABORATORY EVALUATION

CULTURE

On SABHI agar at room temperature, a white, woolly colony with a black reverse rapidly fills the plate. With age, the aerial mycelium turns to gray.

MICROSCOPIC

The hyphae are dark. SHORT; FAT CONIDIOPHORES support SINGLE, oval, smooth,walled, BLACK CONIDIA at the tips.