CRYPTOCOCCUS

SPECIES

Cryptococcus albidus var. albidus
Cryptococcus albidus var. diffluens
Cryptococcus gastricus
Cryptococcus laurentii
Cryptococcus luteolus
Cryptococcus neoformans
Cryptococcus terreus
Cryptococcus unigluttulatus

MICROSCOPIC APPEARANCE

Hyphae septate, hyaline. Conidiophores hyaline, short and inflated. Conidia black, unicellular, ovoid to ellipsoidal, smooth walled, with a thin equatorial germ slit.

MACROSCOPIC APPEARANCE

Surface: Texture flat, often mucoid and moist with smooth edges; White becoming pinkish-brown with age on surface.
Reverse: Cream to tan.
Growth Rate: Rapid to very rapid growth.

DISTINGUISHING FEATURES

Cryptococcus cells are spherical and may bud at any point on the surface or simultaneously at several points; a prominent feature is a mucoid polysaccharide capsule which may vary in width from very thin to several times the radius of the parent cell and buds combined. All species of Cryptococcus lack fermentative ability.

HABITAT

Once thought to be widespread in nature, its true niche appears to be narrowing to a saprobic association with the manure and nests of pigeons; it is therefore essentially global in distribution.

PATHOGENICITY

A species that causes opportunistic systemic cryptococcosis (torulosis) in man and other mammalians. Cryptococcosis is a subacute or chronic infection most frequently involving the tissue of the central nervous system but occasionally producing lesions in the skin, bones, lungs, or other internal organs. Cryptococcal meningitis is extremely common in AIDS patients. Also, Cryptococcus parasitizes cats in some areas, although strains vary in virulence. The other species of this genus are commonly considered nonpathogenic but may occasionally cause disease in severely immunosuppressed patients.

RECOMMENDED MEDIA

Incubate aerobically at 35 and 25 degrees C. for 72 hours.

Note: C. neoformans grows at both temperatures, other Cryptococcus species are inhibited at 35 degrees C.

REFERENCES

1. Hensyl, William R., et al. 1990. Stedman's Medical Dictionary , 25th ed. Williams & Wilkins, Baltimore, MD.

2. St. Germain, Guy and Summerbell, Richard, Ph.D. Identifying Filamentous Fungi , 1st ed. Star Publishing Company, Belmont, CA, 1996.

3. Larone, Davise H. 1995. Medically Important Fungi, A Guide to Identification , 3rd ed. American Society for Microbiology Press, Washington, D.C.

4. The Oxoid Vade-Mecum of Microbiology . 1993. Unipath Ltd., Basingstoke, UK.


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