Dimorphic Fungi Flashcards
What makes a fungi “dimorphic”
Grow as a mold at 25-30C and in nature and grow as a yeast (or yeast-like or spherule) at 37C or in tissue
Who can be infected from dimorphic fungi?
“Normal” people
What is the infective stage of the fungi, mold or yeast?
mold stage
What tests can you run on a direct smear?
Giemsa, GMS, H&E, Gram stain, ect.
What temperature and plates do you use for molds?
25-30C usually on SAB, PDA, PFA
What temperature and plates do you use for yeasts?
37C usually on enriched media (BHI with blood)
Name the 6 Dimorphic Fungi
Sporothrix Schenckii Histoplasma capsulatum Blastomyces dermatitidis Paracoccidioides brasiliensis Penicillium marneffei
Sporotrichosis:
- Primary Clinical presentation
non-healing ulcer at inoculation site; finger, hand, arm, leg
Sporotrichosis:
- Secondary Clinical Presentation
linear series of nodules and draining ulcers along lymphatics
(pulmonary form is RARE)
Sporotrichosis:
- At Risk Occupations
Gardeners
Farmers
Florists
Horticulturists
Sporotrichosis:
- what plants cause infections
rose thorns and sphagnum moss
Sporotrichosis:
- Morphology of yeast
small, round or show the “cigar shape”
Sporotrichosis:
- Morphology of mold
septate hyphae with floweriness or rosettes of conidia
Histoplasmosis:
- At risk population and symptoms
Otherwise “healthy” people
- most habe asymptomatic infection
- may have calcification in lungs, liver, spleen
Histoplasmosis:
- clinical presentation in immune suppressed people
disseminated disease
Histoplasmosis:
- endemic area
Mississippi River Valley (Ohio River, Missouri River)
Histoplasmosis:
- What is it associated with?
soil enriched by droppings of blackbirds, chickens and bats (nitrogen content)
“Spelunker’s disease”, “Cave disease”, “Darlings Disease”
Histoplasmosis:
- Should we skin test people from the midwest? Why or why not?
80-85% of people living in the midwest test positive for histoplasma skin test and show antibodies in their serum (so skin test is worthless)
Histoplasmosis:
- Yeast appearance
SMALL yeast inside monocytes or macrophages; usually in clumps; often gives a hint of “halo” but there is NO CAPSULE
Histoplasmosis:
- Mold appearance
shows spiked or “tuberculate” macroconidia
Histoplasmosis:
- Three available tests for diagnosis
- Which one is diagnostic in disseminated disease?
- Skin test
- Serum antibodies
- URINE ANTIGEN TEST (diagnostic)
Blastomycosis:
- Primary clinical presentation
Most asymptomatic; may progress to chronic pulmonary disease, cutaneous ulcers or pustules may mimic cancer!
Blastomycosis:
- Endemic area
States adjacent to Mississippi and Ohio rivers
Blastomycosis:
- Yeast appearance
BIG, thick cell wall, single bud with a BROAD BASE,
