Wednesday 14 March 2007
Definition: Infection by Cryptococcus neoformans.
Cryptococcosis, or cryptococcal disease, is a potentially fatal fungal disease.
It is caused by members of the Cryptococcus neoformans species complex, comprising the three variants C. neoformans v. gattii (Cryptococcus gattii), C. neoformans v. neoformans, and C. neoformans v. grubii.
Cryptococcosis is believed to be acquired by inhalation of the infectious propagule from the environment. Although the exact nature of the infectious propagule is unknown, the leading hypothesis is the basidiospore created through sexual or asexual reproduction.
Cryptococcosis is a defining opportunistic infection for AIDS. Other conditions which pose an increased risk include certain lymphomas (e.g. Hodgkin’s lymphoma), sarcoidosis, and patients on long-term corticosteroid therapy.
Distribution is worldwide. The prevalence of cryptococcosis has been increasing over the past 20 years for many reasons, including the increase in incidence of AIDS and the expanded use of immunosuppressive drugs.
Cryptococcus gattii causes infections in immunocompetent people (those having a functioning immune system), but C. neoformans v. grubii, and v. neoformans usually only cause clinically evident infections in persons who have some form of defect in their immune systems (immunocompromised persons).
People who have defects in their cell-mediated immunity, for example, people with AIDS, are especially susceptible to disseminated cryptococcosis.
Cryptococcosis can rarely occur in the immunocompetent person without HIV, when it usually goes undiagnosed. Less than 250 cases in all are reported in the medical literature, the majority diagnosed postmortem.
- wound cryptococcosis or cutaneous cryptococcosis
- pulmonary cryptococcosis
- menigeal cryptococcosis (cryptococcal meningitis)
- cryptococcal meningoencephalitis
Symptoms include fever, fatigue, chest pain, dry cough, swelling of abdomen, headache, blurred vision and confusion.
Detection of cryptococcal antigen (capsular material) by culture of CSF, sputum and urine provides definitive diagnosis.
Blood cultures may be positive in heavy infections.
Cryptococcosis is often fatal, especially if untreated.
Treatment options in non-AIDS patients who have reduced immune-system function is not well studied. Intravenous Amphotericin B combined with oral flucytosine may be effective.
Every attempt should be made to reduce the amount of immunosuppressive medication until the infection is resolved.
AIDS patients often have a reduced response to Amphotericin B and flucytosine, therefore after initial treatment as above, oral fluconazole can be used.
Sing Y, Ramdial PK. Cryptococcal inflammatory pseudotumors. Am J Surg Pathol. 2007 Oct;31(10):1521-7. PMID: 17895752