Yeasts (single celled with “buds” ==> blastospores)

An example of yeast is Cryptococcus Neoformans. It causes cryptococcosis (systemic mycosis) and its primary site of infection is the lungs. But it can spread to other parts of the body (leading cause of fungal meningitis in AIDS patients). The organism grows as a budding yeasts (blastospores), contains a polysaccharide coat important for diagnosis.

Diagnosis is by detection of crypto coccal polysaccharide antigens in CSF. A latex compound with antibodies to Cryptococcus organism is present, and the antigenic polysaccharide coat binds to this. Culturing on Sabornauds is useful to detect the specific organism.

Treatment is by Amp B (but poor penetration through CSF) + 5-fluorocytosine (good penetration into CSF but resistance is problem).

Category: Microbiology Notes