Histoplasma, Blastomyces, Zygomyces

Question 1

Define Thermally Dimorphic

Answer 1

These organisms grow as filamentous molds in nature but grow as yeasts in the human body.

Question 2

Histoplasa Capsulatum Geographic Location:

Answer 2

Ohio and Mississippi River Valleys

Question 3

Histoplasma Capsulatum: grows in soil contaminated with:

Answer 3

Bird and bat droppings

Question 4

Blastomyces Dermatitidis Geographic Location:

Answer 4

Ohio, Mississippi, Missouri, and Arkansas River Valleys, esp in upper Minnesota and Wisconsin

Question 5

Coccidioides Immitis Geographic Location:

Answer 5

SW USA, California, New Mexico, Arizona, Texas and Mexico.

Question 6

Paracoccidioides Brasilliensis Geographic Location:

Answer 6

Restricted to Central and South America where fungus grows in soil.

Question 7

Penicillium Marneffei Geographic Location:

Answer 7

Southeast Asia

Question 8

What population is Penicillium Marneffei exclusively seen in?

Answer 8

AIDs pts.

Question 9

What does coccidoides grows as in vivo/37 C?

Answer 9

Spherules filled with tiny yeasts.

Question 10

What is the transmission of these three musketeer molds?

Answer 10

Blasto, histo, and coccidioido are all transmitted via inhalation of spores/conidita in the dust from the environment. In the lung they germinate and convert to yeasts.

Question 11

Describe how Histoplasmosis resembles TB?

Answer 11

histoplasmosis capsulatum replicates intracellularly within macrophages, forms granulomatous lesions and needs CMI for recovery.

Question 12

Describe the disease spectrum of histoplasmosis capsulatum

Answer 12

Asymptomatic infection–> Mild Flu-Like Syndrome–> Acute Pulmonary Histoplasmosis–> Chronic (Cavitary) pulmonary histoplasmosis–> Disseminated histoplasmosis.

Question 13

Symptoms of acute pulmonary histoplasmosis

Answer 13

Fever, chills, cough and chest pain with difficulty breathing.

Question 14

Pathogenesis of acute pulmonary histoplasmosis

Answer 14

Diffuse or localized pneumonitis with granulomatous lesions that develop 2-3 weeks after exposure to Histoplasmosis.

Question 15

Complications of acute pulmonary histoplasmosis:

Answer 15

Acute pericarditis, death in untreated immunocompromised cases.

Question 16

What is the pathogenesis of Chronic cavitary pulmonary histoplasmosis?

hint: cavitary

Answer 16

Usually a result of re-activation of a latent infection; develops large cavities in upper lobes of lung.

Can be fatal

Question 17

What population does disseminated histoplasmosis occur in?

Answer 17

Immunosuppressed pts (CD4 count <140) and young children.

Question 18

What is the pathogenesis/complications of disseminated histoplasmosis

Answer 18

Rapid involvement of lymph nodes, bone marrow, heart, adrenal glands, CNS, GI tract, skin and GU tract.

Question 19

What type of outdoor activities can expose someone to blastomycosis?

Answer 19

Collecting firewood, tearing down old building, farming, disrupting soil

Question 20

how does blastomycosis resemble TB?

Answer 20

intracellular replication within macrophages, granulomatous lesions and CMI.

Question 21

What is one difference between TB and blastomycosis.

Answer 21

Blastomycosis has a cutaneous presentation of disease.

Question 22

Describe the disease spectrum of blastomycosis.

Answer 22

Asymptomatic infection–> mild flu-like syndrome–> acute pulmonary blastomycosis–> chronic pulmonary blastomycosis–> Disseminated blastomycosis.

Question 23

Symptoms of acute pulmonary blastomycosis

Answer 23

Resembles a bacterial pneumonia. Sx: high fever, chills, productive cough, pleuritic chest pain. purulent or mucopurulent sputum.

Question 24

Symptoms of chronic pulmonary blastomycosis.

Answer 24

Low grade fever, productive cough, night sweats, weight loss, purulent or mucopurulent hemoptysis.

Question 25

Where is the most common site of extra pulmonary infection with blastomycosis?

Answer 25

The SKIN!

Question 26

What is one difference between Coccidioidomycosis vs. Blasto, Histo, and TB?

Answer 26

The replicating spherule remain EXTRACELLULAR

Question 27

What determines the extent of disease in coccidioidomycosis?

Answer 27

The number of arthroconidia inhaled and the immune response of the host.

Question 28

Describe the disease spectrum of coccidioidomycosis

Answer 28

Asymptomatic infection–> Mild flu like syndrome–> moderate respiratory disease–> disseminated coccidoidomycosis.

Question 29

What are the symptoms of moderate respiratory disease caused by coccidioidomycosis?

Answer 29

An acute illness resembling a bacterial pneumonia. Sx: high fever, shills, cough, fatigue, shortness of breath, night sweats and sputum production. May develop nodules or cavities in lung.

Question 30

Where is the most common site of dissemination of coccidioidomycosis?

Answer 30

The SKIN!

Question 31

What is the most serious and lethal complication of coccidioidomycosis?

Answer 31

Meningitis.

Question 32

What is the best way to diagnosis one of these three disease causing molds?

Answer 32

• Imaging studies
• Samples for direct microscopic examination to look for yeasts/spherules
• Culture (very slow)
• Antigen detection in serum/urine (for histoplasmosis)
• Skin tests
• Serology-IgM titers for coccidioidomycosis.

Question 33

Tx of one of these three molds:

Answer 33

Asymptomatic/mild cases do not require treatment.

Moderate/Severe diseases is difficult to eradicate and requires long term therapy for months to years. “azalea” meds

See notes for specific meds.

Question 34

Prevention of these three muskateer molds.

Answer 34

Anti-fungal prophylaxis in AIDs pts. Particularly useful for histoplasmosis and penicilliosis.