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Chrysosporium  Mold Species

The U.S. Government's Occupational Safety and Health Administration [OSHA] lists the following as the health effects of Chrysosporium mold: Allergen, Irritant, Hypersensitivity pneumonitis, Dermatitis.

Taxonomic Classification

Kingdom: Fungi
Phylum: Ascomycota
Class: Euascomycetes
Order: Onygenales
Family: Onygenaceae
Genus: Chrysosporium


Culture of Chrysosporium tropicum

Chrysosporium tropicum showing typical pyriform to clavateshaped conidia with truncated bases which may be formed either intercalary, laterally or terminally.

Colonies are moderately fast growing, flat, white to tan to beige in colour, often with a powdery or granular surface texture. Reverse pigment absent or pale brownish-yellow with age. Hyaline, one-celled (ameroconidia) are produced directly on vegetative hyphae by non-specialized conidiogenous cells. Conidia are typically pyriform to clavate with truncate bases (6 to 7 by 3.5 to 4 um) and are formed either intercalary (arthroconidia), laterally (often on pedicels) or terminally. No macroconidia or hyphal spirals are seen.

Description and Natural Habitats

Chrysosporium is a keratinophilic filamentous fungus commonly isolated from soil, plant material, dung, and birds. It lives on remains of hairs and feathers in soil. The telemorphs of Chrysosporium spp. are included in the genera Aphanoascus, Nannizziopsis, and Uncinocarpus. As well as being a common contaminant, Chrysosporium is occasionally isolated from human infections.


The genus Chrysosporium contains several species. The most common ones are Chrysosporium keratinophilum, Chrysosporium tropicum, Chrysosporium merdarium, Chrysosporium inops, Chrysosporium pannicola, Chrysosporium queenslandicum, and Chrysosporium zonatum. Another species of special interest, classified as Emmonsia parva on the ecological basis, is occasionally named as Chrysosporium parvum as well.

The species of Chrysosporium are differentiated from each other by the texture of the colony and morphology, location, and size of the conidia. Also, some species, particularly Chrysosporium pannicola, do not grow at 37C.

Species of Chrysosporium are occasionally isolated from skin and nail scrapings, especially from feet, but because they are common soil saprophytes they are usually considered as contaminants. There are about 22 species of Chrysosporium, several are keratinophilic with some also being thermotolerant, and cultures may closely resemble some dermatophytes, especially Trichophyton mentagrophytes, and some strains may also resemble cultures of Histoplasma and Blastomyces.

Pathogenicity and Clinical Significance


Chrysosporium spp. may cause skin infections and onychomycosis in humans. In addition to these superficial infections, Chrysosporium spp. have occasionally been isolated from systemic infections in bone marrow transplant recipients and in patients with chronic granulomatous disease. The high mortality rate of systemic Chrysosporium infections is noteworthy.

Macroscopic Features

Chrysosporium colonies grow moderately rapidly at 25C. The morphology of the colonies is very variable. They may be granular, woolly, or cottony and flat, or raised and folded in appearance. From the front, the color is white cream, yellow or tan to pale brown. The reverse is white to brown.

Microscopic Features


Chrysosporium produces hyphae, conidia (aleuriconidia), and arthroconidia. Hyphae are septate while the conidia are hyaline, broad-based, one-celled, and smooth- or rough-walled. These conidia are broader than the vegetative hyphae and occur terminally on pedicels, along the sides of the hyphae, or in intercalary positions. The conidia usually have an annular frill which is the reminant of the hyphal wall that remains after detachment from the hypha. Arthroconidia, on the other hand, are abundant and larger than their parent hyphae in diameter. In addition, Chrysosporium parvum forms enlarged, thick-walled cells (adiaspores) at 37-40C.


Laboratory Precautions

No special precautions other than general laboratory precautions are required.


Very limited data are available. Amphotericin B, itraconazole, ketoconazole, and voriconazole tend to yield low MICs for Chrysosporium keratinophilum isolates. Fluconazole MICs are relatively higher than those of the just noted antifungal agents. Flucytosine, on the other hand, appears to have no in vitro activity against these isolates.

The mycological information gathered and organized in this extensive research on different Pathogenic Molds was  sourced out from the list of informative websites below: | | | | | | | | | | | | | | | |


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