Endemic fungi/Dimorphic fungi

Question 1

Name the 6 endemic “dimorphic” fungi

Answer 1

1. Blastomyces dermatitidis
2. Coccidiodes immitis
3. Histoplasma capsulatum
4. Sporothrix
5. Talaromyces marneffei
6. Paracoccidiodes brasilensis

Question 2

Where is Coccidiodes found?

And what does it cause?

Answer 2

C. immitis found in Central and Southern California

C. posadasii found in Arizona, New Mexico, Texas, Mexico, Central and South America

Causes Valley Fever - lung infection after breathing in dush with arthroconidia

Question 3

What does Coccidiodes look like in pathology?

What does it look like at 30 degrees?

Answer 3

Spherules with endospores (NOT A YEAST at 37)

Barrel-shaped arthroconidia alternating with disjunctor cells (easily break off)

Question 4

Mimics of Coccidiodes?

Answer 4

Geotrichum and Malbranchea

Question 5

Cocci diagnostics?

Week 1-4

After Week 3

Answer 5

Week 1-4: PCR, Culture, Pathology

Week 3 +:
1. Serology enzyme immunoassay
(cross reacts with Histo and Blasto)

2. Complement fixation (Ab + Ag complex inactivation complement, so RBC are not lyzed in positive samples)
3. Immunodiffusion Precipitation occurs where Ag and Ab merge

Question 6

Where is Histoplasma found?

Answer 6

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

Question 7

What does Histoplasma look like in pathology and at 30 degrees?

Answer 7

Pathology: acorn inside of macrophages (GMS and PAS positive)

30 degrees: tuberculate macroconidia

Question 8

Does Histoplasma cause disseminated infections in healthy people?

Answer 8

Not really, only immunocompromised

Inhaled spores may spread to bone marrow, lymph nodes, skin

Question 9

How is Histoplasma recovered from patient samples?

Answer 9

Isolator tubes-lyze blood cells and prevent coagulation. The organisms inside of RBCs are released and concentrated

Question 10

Diagnostics for Histo detection?

Answer 10

Serology: EIA, Complement fixation, Immunodiffusion

PCR

Antigen (urine more sensitive than serum) but cross-reacts with Blasto. Urinary antigen used to determine if therapy is working….

Antitbody testing is not suitable for immunocompromised patients and during acute pulmonary disease

Question 11

Mimic of Histoplasma?

Answer 11

Scedosporium - does not grow incyclohexamide

Question 12

Where is Blastomyces found?

Answer 12

In the Eastern states of the US and Africa

Question 13

What does Blasto look like in host and at 30 degrees?

Answer 13

Host: Broad based budding yeast (8-15uM) GMS and PAS stain

In culture: lollipop on a string or birds on a wire

Question 14

Does Blasto affect healthy host?

Answer 14

Not really, just immunocompromised

inhaled spores may spread hematogenously

Question 15

Mimic of Blasto?

Answer 15

Chrysosporium and maybe Trichophyton

Question 16

Diagnostic options for Blasto?

Answer 16

Serology: EIA and Purified antigen A

Question 17

Which dimorph produces diffusible red pigment

Answer 17

Talaromyces marneffei

(Penicillium before)

Question 18

how does Talaromyces look in the host and in culture?

Answer 18

Host/histopathology: yeast growing by BINARY FUSSION arthroconidia (no budding in histopath)

Culture: looks like penicillium (Helpful to know patient history)

Question 19

Where is Talaromyces found? and What does it cause?

Answer 19

Southeast Asia

Talaromycosis- small bumps on skin in healthy people, but may disseminate in immunocompromised

Question 20

Paracocci

Question 21

Sporothrix schenckii

Answer 21

Found in the soil worldwide

Looks like cigars in histopath

After innoculation, it may spread through the lymphatics, Nodular Lymphangitis, spread along blood vessels of arm

Question 22

Sporothrix brasilensis

Answer 22

Found in Brazil and transmitted to humans from animals (cats)

Question 23

General information

Answer 23

Echinocandins (caspofungin, micafungin) not active against dimorphic fungi in vivo. These inhibit 1,3-β-D-glucan