Cryptococcosis

Cryptococcosis is a systemic fungal infection, caused by encapsulated yeast of the genus Cryptococcus, C neoformans and C gattii. These environmental microorganisms live in pigeon and other bird droppings, as well as in the fruit and bark of various trees. Infection in humans and other animal species usually occurs by inhalation and less frequently through the skin and by ingestion of the fungus. Most infections have a benign course and resolve spontaneously; however, the incidence of cryptococcosis has increased considerably, mainly due to diverse causes of immunodeficiency, particularly AIDS. Cryptococcus neoformans infections are common, worldwide, and severe forms are seen in immunocompromised patients. Cases caused by C gattii predominate in tropical or subtropical regions. Cryptococcosis may present as an acute, subacute, or chronic lung disease, as a nonpurulent cerebrospinal fluid meningitis, or as a severe infection with fever, anemia, lymphadenopathy, and hepatosplenomegaly. The eye can be affected, with partial or total loss of vision. Diagnosis is by direct observation of the causative agent, in histopathologic studies, by isolation in culture, and by the presence of capsular antigen. Treatment is the intravenous administration of amphotericin B deoxycholate, alone or combined with 5-fluorocytosine or fluconazole, which can be given orally or intravenously. Itraconazole is less effective when the central nervous system is affected. Voriconazole appears to be a drug that can be used in these patients. In AIDS patients, secondary prophylaxis is administered with fluconazole or amphotericin B and is continued until CD4 cell counts exceed 200 cells/μL. Evaluation of intracranial pressure is important in the first weeks after diagnosis in AIDS patients.