Systemic Mycoses

Question 1

List the fungi that are considered systemic mycoses (4)

Answer 1

Histoplasma capsulatum
Blastomycosis dermatitidis
Coccidioides immitis
Paracoccidioides brasiliensis

Question 2

For fungal infections in general, who is most at risk for developing systemic disease?

Answer 2

The immunocompromised. Many fungal infections are asymptomatic in most healthy people.

Question 3

What disease is caused by histoplasma?

Answer 3

Histoplasmosis

Question 4

Geographic area endemic to histoplasmosis

Answer 4

Midwestern/central USA along Mississippi and Ohio River Valley

Question 5

Histoplasmosis transmission

Answer 5

Through respiratory tract. Associated with bird or bat droppings. Spores in bird/bat droppings are inhaled - these go to the lungs. Then they get ingested by macrophages.

May mention someone who has recently been in a cave or has been exposed to chicken coups (farmer)

Question 6

What would histoplasmosis look like under microscope?

Answer 6

Macrophage filled with small, intracellular oval bodies. It is ovoid.

Sample is stained with KOH Prep.

Histo is much smaller than a RBC. Macrophage is only slightly larger than a RBC, Many Histo’s can fit inside the macrophage.

Question 7

How do you diagnosis histoplasmosis?

Answer 7

Culture - takes a long time

Better option is rapid histoplasma urine or serum antigen tests

Question 8

Histo dimorphism

Answer 8

Mold in the cold (soil). Yeast in the heat (body).

Question 9

Histoplasmosis clinical presentation

Answer 9

Normally, the systemic fungi do not produce any symptoms, but they can cause granulomas

In the unlucky few that do show symptoms, it causes a pneumonia.

Lungs develop granulomas which eventually calcify leading to chronic pulmonary issues

Chronic Histo looks a lot like TB - cavitary lesions in upper lobes, calcified nodules with fibrotic scarring (mostly in hilar region)

Besides pneumonia, Histo can also cause erythema nodosum - painful red nodules on shins (normally)

Question 10

Systemic Histoplasmosis Presentation

Answer 10

Systemic fungi are especially associated with the immunocompromised

When an immunocompromised person gets histo they get hepatosplenomegaly

Gross path will show calcifications in liver and spleen - the fungus targets reticuloendothelial system which has lots of macrophages.

Patients can also develop skin and neuro findings

Question 11

Histoplasmosis Tx

Answer 11

Local/mild infection: Use azole drugs (Fluconazole, Ketoconazole)

Systemic: Amphoteric B - lots of side effects, reserved for life-threatening systemic cases

Question 12

What geographic region is most associated with Blastomycosis?

Answer 12

Great Lakes and Ohio River Valley (some southern too) - similar to Histo. Blasto is on east coast though… Histo doesn’t reach that far east

Question 13

Blastomycosis dimorphism

Answer 13

Mold in the cold (soil), Yeast in the heat (body)

Question 14

Blastomycosis transmission

Answer 14

Inhalation of aerosolized spores

Question 15

Blastomycosis replication

Answer 15

Single broad-based budding once it’s in the body

Question 16

What does Blasto look like?

Answer 16

Fairly large. Same size as RBC.

Question 17

Blasto in the lungs

Answer 17

Causes lungs to have patchy alveolar infiltrate on CXR (haziness). Also lesions and cavitations.

Pneumonia can be acute or chronic and is considered a local lung infection.

Majority of infections are subclinical.

Question 18

Blastomycosis dissemination

Answer 18

Immunocompromised

Dissemination from lungs most likely occurs in skin and bone

Osteomyelitis

Question 19

Diagnosis of Blastomycosis infection

Answer 19

Done through KOH prep or through culture

On KOH you’ll see round yeast with single, broad based bud.

Can also detect with rapid urine antigen test

Question 20

Blastomycosis Tx

Answer 20

Local: Azoles (Itraconazole)

Disseminated: Amphotericin B (usually in immunocompromised)

Question 21

What geographic region is most associated with coccidioides?

Answer 21

California and SW USA

Question 22

Coccidioides transmission

Answer 22

Inhalation of spores in dust

Chance of infection goes up a ton when large amounts of dust goes into the air - frequent dust storms in San Joaquin Valley of California cause large incidence

Coccidioides infection sometimes called “San Joaquin Valley Fever”

Large amounts of dust is also kicked up during earthquakes - incidence can increased 10x

Question 23

Coccidioides dimorphism

Answer 23

Mold in Cold

Spherules filled with endospores in the body (WHAT?! IT’S DIFFERENT?!?!)

Question 24

What does coccidioides look like?

Answer 24

Spherules are larger than RBCs

Coccidio > Blasto > Histo

Question 25

Coccidioides presentation

Answer 25

Asymptomatic/subclinical in most healthy people

In some, it presents as self-limited acute pneumonia with fever, sweats, arthralgias - can last for a couple weeks

Radiographic images may show either nothing (majority of cases) or cavities and/or nodules

Also associated with erythema nodosum (red, extremely tender nodules on shins)

REMEMBER! E.N. represents a robust immune response (you don’t see this in immunocompromised)

Question 26

Disseminated Coccidioides

Answer 26

Immunocompromised

May disseminate to the bone in these patients (skin and lungs too)

Can also disseminate to meninges and cause meningitis

Question 27

Coccidioides diagnosis

Answer 27

KOH stain or culture (takes a while). Could send off serum and check for antibodies too (like all systemic mycoses - IgM presence against it demonstrates infection)

Question 28

Coccidioides Tx

Answer 28

Local: Ketoconazole

Systemic: Amphotericin B

Question 29

What geographic region is most often associated with paracoccidioides?

Answer 29

Brazil and South America

Question 30

What does paracoccidioides look like?

Answer 30

“Captain’s Wheel” in yeast form (in the lungs)

Very large. ~ Coccidioides size.

Paracoccidioides = Coccidioides > Blasto > Histo

Question 31

Paracoccidioides dimorphism

Answer 31

Mold in environment

Yeast in heat

Question 32

Paracoccidioides transmission and presentation

Answer 32

Respiratory droplets

Once these are inhaled, the fungus disseminates and causes lymphadenopathy - cervical, axillary, even inguinal

As it progresses from cervical it moves down to affect upper respiratory tract and lungs - causing granulomas in lungs

Development of mucosal ulcers in Upper Respiratory Tract - mucocutaneous lesions (esp mouth) - often in gums

Have ragged borders with small spots of hemorrhage

Remember!! Mucocutaneous lesions and lymphadenopathy

Question 33

Paracoccidioides Tx

Answer 33

Local: Itraconazole
Severe: Amphotericin B