Endemic fungi/Dimorphic fungi Flashcards
Name the 5 endemic “dimorphic” fungi
- Blastomyces dermatitidis
- Coccidiodes immitis
- Histoplasma capsulatum
- Talaromyces marneffei
- Paracoccidiodes brasilensis
Sporothrix - not endemic! just dimorphic
Where is Coccidiodes found?
And what does it cause?
C. immitis found in Central and Southern California
C. posadasii found in Arizona, New Mexico, Texas (El Paso), Mexico, Central and South America
Causes Valley Fever - lung infection after breathing in dush with arthroconidia
What does Coccidiodes look like in pathology?
What does it look like at 30 degrees?
Spherules with endospores (NOT A YEAST at 37)
Barrel-shaped arthroconidia alternating with disjunctor cells (easily break off)
Mimics of Coccidiodes?
Geotrichum (saprophyte) and Malbranchea
Mimics of Coccidiodes?
Geotrichum and Malbranchea (Saprophyte)
Cocci diagnostics?
Week 1-4
After Week 3
Week 1-4: PCR, Culture, Pathology
Week 3 +:
1. Serology enzyme immunoassay
(cross reacts with Histo and Blasto)
- IgG detection by Complement fixation (Ab + Ag complex inactivate complement, so RBC are not lysed in positive samples)
- IgG detection by Immunodiffusion Precipitation (occurs where Ag and Ab merge)
Where is Histoplasma found?
In bird and bat guano, and environment in general
Found in the Eastern and central-ish part of the US, Central America, South America, South Africa
Found in Texas Oklahoma, and upwards
What does Histoplasma look like in pathology and at 30 degrees?
Pathology: very small yeast with narrow based budding, sometimes in macrophages (GMS and PAS positive)
30 degrees: tuberculate macroconidia
Does Histoplasma cause disseminated infections in healthy people?
Not really, only immunocompromised
Immunocompetent: tuberculosis-like illness in lungs with necrotizing granulomas (appears like CAP)
Immunocompromised: lung disease and disseminated disease with poor prognosis (skin lesions/papules)
Histoplasma capsulatum var capsulatum: most common cause of histoplasmosis
Histoplasma capsulatum var duboisii: cause of African histoplasmosis
How is Histoplasma recovered from patient samples?
Isolator tubes-lyze blood cells and prevent coagulation. The organisms inside of RBCs are released and concentrated
Diagnostics for Histo detection?
Serology: EIA, Complement fixation, Immunodiffusion
PCR
MiraVista Antigen (urine more sensitive than serum) but cross-reacts with Blasto. Urinary antigen used to determine if therapy is working….
Antibody testing is not suitable for immunocompromised patients and during acute pulmonary disease
Mimic of Histoplasma?
Sepedonium-soil fungi, not dimorphic
Where is Blastomyces found?
In the Eastern states of the US and Africa
What does Blasto look like in host and at 30 degrees?
Host: Broad based budding yeast (8-15uM) GMS and PAS stain
In culture: lollipop on a string or birds on a wire
Does Blasto affect healthy host?
Not really, just immunocompromised
inhaled spores from soil may spread hematogenously
Common sites: Lung, skin lesions, bone, genitourinary system
Can also infect dogs (human and dog go hiking, both catch Blasto)
Mimic of Blasto? (2)
Chrysosporium (soil saprophyte, sometimes on skin and nails)
and maybe Trichophyton rubrum (dermatophyte)
Diagnostic options for Blasto?
Serology: EIA and Purified antigen A
Which dimorph produces diffusible red pigment
Talaromyces marneffei
(Penicillium before)
Talaromyces marneffei
* yeast/mold
* Treatment
Host/histopathology: yeast growing by BINARY FUSSION arthroconidia (no budding in histopath)
Culture: looks like penicillium
Found in **Southeast Asia, Southern China, and India **
Treatment: amphotericin B and itraconazole
Where is Talaromyces found? and What does it cause?
Southeast Asia, Souther China, and India
Talaromycosis- small bumps on skin in healthy people, but may disseminate in immunocompromised
Where is Paracocci found and what does it cause? and treatment?
Mexico and Central and South America
Most cases: Brazil, Venezuela, Colombia, and Argentina
Paracoccidioidomycosis - in adults usually affects the lungs and causes lesions in the mouth and throat.
Children are more likely to have swollen lymph nodes and skin lesions.
TMP/SMX
Sporothrix schenckii
Found in the soil worldwide
Looks like cigars in histopath
After innoculation, it may spread through the lymphatics, Nodular Lymphangitis (Nocardia) spread along blood vessels of arm
Sporothrix brasilensis
Found in Brazil
causes cat-transmitted sporotrichosis, a zoonotic disease affecting humans, cats, and dogs,
General information
Echinocandins (caspofungin, micafungin) not active against dimorphic fungi in vivo. These inhibit 1,3-β-D-glucan
