Curvularia Species

ENVIRONMENTAL

Found worldwide, this fungus is frequently recovered from grass, leaves, and decaying vegetation. These fungi form a rapidly growing phaeoid colony that is cottony and dirty gray to black.

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

Curvularia spp. isolates are usually implicated in chronic sinusitis in immunocompetent patients. It usually causes keratomycosis, but occasionally it may produce mycetoma (draining subcutaneous lesions on the extremities), endocarditis, pulmonary infection, allergies, and infection of the nasal septum.

LABORATORY EVALUATION

CULTURE

On SABHI agar at room temperature, the colony is moderately rapid-growing, cottony, and white, light pink, orange, or green, with a brown reverse.

MICROSCOPIC

The septate mycelium is DARK, Large, four- to five-celled, dark POROCONIDIA are borne on a BENT-KNEE shaped CONIDIOPHORE. The poroconidia are centrally distended owing to an OVER_ENLARGED CENTRAL CELL, and the ends are lighter than the middle. Multicelled conidia are produced on sympodial conidiophores. This genus is among the easiest to identify because of the frequently seen crescent-shaped conidia with three to five cells of unequal size and an enlarged central cell.