[Cryptococcosis]

Cryptococcus neoformans is a ubiquitous encapsulated yeast present in soil. The usual contamination is by the respiratory route with ensuing dissemination in predisposed patients. Acquired immunodeficiency syndrome is the leading predisposing factor and illustrates the role of cellular immunity. Corticosteroid therapy and diseases of the reticulo-endothelial system can also encourage the disease. The most common visceral localization is the central nervous system, with meningo-encephalitis. In AIDS and severely immunocompromised patients multivisceral dissemination may occur. The organism is detected by culture, smear and/or biopsy. The serological test with detection of the cryptococcal polysaccharide capsular antigen is of great help for the diagnosis. The discovery of four serotypes of C. neoformans and of biochemical differences between serotypes has increased our knowledge of the ecology and epidemiology of the organism. Serotype A strains are the most common in both natural and clinical isolates, serotypes B and C are more prevalent in clinical isolates in tropical countries; their ecological site in nature is unknown. The disease bears a poor prognosis, especially in the most immunocompromised patients. The standard treatment is a combination of amphotericin B and flucytosine, but it can be toxic to the bone marrow. Considerable interest has arisen in new potential anticryptococcal agents currently under experimental study, such as itraconazole and fluconazole.