Mycosis Flashcards
dimorphic fungi
two forms exist for one fungus species depending on temperature and conditions of environment
2 forms of fungi
mycelial and yeast/yeast-like
Dimorphic fungi capable of causing systemic infection
Histoplasma capsulatum Blastomyces dermatitidis Coccidioides immitis Paracoccidioides brasiliensis Sporothrix schenckii
Histoplasma capsulatum
-Associate with Bat guano (Spelunker) and bird
droppings
-Fungal Culture incubated at 30˚ C
Histoplasmosis Disease
Reactivation disease can occur in elderly and
immunosuppressed (AIDS is a good example)
Bone marrow exam is useful in diagnosing disseminated
infections
Mucocutaneous lesions are common
and a site of dissemination
yeast of Histoplasma capsulatum
prefer to
be intracellular and inhabit Macrophages.
Yeast are small 2 – 4 um, regular in size, and
oval to round. Yeast do not have a capsule,
this is just a staining artifact.
Histoplasmosis rapid diagnosis
Antigen detection in urine
Most useful for disseminated infection and chronic
pulmonary disease
Antigen is detectable in >=85% of these infections
Good for immune suppressed patients that do not
produce a detectable antibody response