Eukaryotes Genomes - CRYPTOCOCCUS NEOFORMANS

The basidiomycete fungus Cryptococcus neoformans is an opportunistic pathogen of worldwide importance that causes meningitis, leading to death in immunocompromised individuals. Unlike many basidiomycete fungi, C. neoformans is thermotolerant, and its ability to grow at 37°C is considered to be a virulence factor.

Cryptococcus is an encapsulated yeast. Following its first identification in nature from peach juice samples, the major environmental sources of Cryptococcus neoformans have been shown to be either soil contaminated with pigeon droppings ( Cryptococcus neoformans var. neoformans) or eucalyptus trees and decaying wood forming hollows in living trees ( Cryptococcus neoformans var. gattii). It is not part of the normal microbial flora of humans.

The genus Cryptococcus includes around 37 species. Among these, Cryptococcus neoformans is the only species that is pathogenic. Cryptococcus neoformans produces round, budding yeast cells and is the causative agent of cryptococcosis. Given the neurotropic nature of the fungus, the most common clinical form of cryptococcosis is meningoencephalitis. The course of the infection is usually subacute or chronic. Cryptococcosis may also involve the skin, lungs, prostate gland, urinary tract, eyes, myocardium, bones, and joints. The infection commonly starts following inhalation of the organism. The primary infection may remain localised into the lungs or disseminate throughout the body. Cryptococcocal meningitis can only occur once the fungus has reach CNS tissue from the primary point of entry. Based on this, most authors consider any form of extra-pulmonary cryptococcosis to be a form of disseminated disease. Primary pulmonary infections have no diagnostic symptoms and usually are asymptomatic. However, a chronic form may develop producing a variety of lesions.

If untreated, cryptococcal meningoencephalitis is 100% fatal, and even when treated with the most effective antifungal drugs, cryptococcal infections can be fatal if the host does not have adequate T-cell­dependent immune function.

References:

http://www.doctorfungus.org/thefungi/Cryptococcus.htm
http://www.cdc.gov/ncidod/EID/vol4no1/buchanan.htm