Dimorphic Fungi Study Aids

What does Blastomyces dermatitidis cause?

Blastomycosis

What is Blastomycosis?

A chronic infection throughout the body characterized by granulomatous lesions

Where is blastomycosis primarily located?

Lungs, skin, and bones

How does Blastomyces dermatiditis grow?

Slowly

Describe the appearance of blastomyces dermatitidis at 25 degrees Celsius

1. Yeast-like

2. Prickly

3. Cottony

4. Aerial mycelium turns tan or brown with age

Describe the appearance of Blastomyces dermatitidis at 37 degrees Celsius

1. Cream to tan in color

2. Heaped or wrinkled

3. Waxy

What can inhibit the yeast phase of Blastomyces dermatitidis?

1. Chloramphenicol

2. Cyclohexamide

What organism is this? What temperature?

Blastomyces dermatitidis at 25 degrees Celsius

What organism is this, and at what temperature?

Blastomyces dermatitidis at 37 degrees Celsius

What is the microscopic morphology of Blastomyces dermatiditis at 25 degrees Celsius?

Septate hyphae with round or pear shaped conidia

What is the microscopic morphology of Blastomyces dermatitidis at 37 degrees Celsius?

Broad-based walls with thick buds

What organism can Blastomyces dermatiditis often be confused with?

Chrysosporium

What organism is this?

Blastomyces dermatitidis

What is the clinical significance of coccidiodes immitus?

It causes coccidiodomycosis

What is coccidiodomycosis?

A highly infectious disease that can be acute or chronic, benign or fatal. Can infect multiple body systems. Endemic to arid SW US

Describe the macroscopic appearance of Coccidiodes immitus at 27 and 37 degrees

White, aerial, cottony mycelium that turns tan to brown with age

How quickly does Coccidiodes immitus grow?

3-5 days, but arthrospore production may take 1-2 weeks

What organism is this?

Coccidiodes immitus

Describe the microscopic appearance of coccidiodes immitus

Course, septate, branched hyphae with arthrospores alternating with empty disjunctor cells.

What organism is this?

Coccidiodes immitus

What organism is this?

Spherule of coccidiodes immitus

What is the clinical significance of Histoplasma capsulatum?

Histoplasmosis

What is Histoplasmosis?

Can be acute, benign pulmonary disease or chronic and fatal.

How quickly does Histoplasma capsulatum grow?

Slowly

Describe the macroscopic appearance of H. capsulatum at 25 degrees Celsius

White cottony mycelia

Describe the appearance of H. capsulatum at 37 degrees Celsius

Moist, white, yeast-like colonies

What organism is this? What temperature?

H. capsulatum at 25 degrees

Describe the microscopic structure of H. capsulatum at 25 degrees in young cultures

Round to smooth, pear-shaped, spiny microconidia

Describe the microscopic structure of H. capsulatum at 25 degrees in mature cultures

Tuberculate macroconidia (flower)

Describe the microscopic morphology of H. capsulatum at 37 degrees Celsius

Small, round budding cells

What organism is this, and at what temperature?

H. capsulatum 25 degrees celsius (mature)

What organism is this, and what temperature?

H. capsulatum at 37 degrees Celsius

What is the clinical significance of Sporothrix schenckii?

Causes sporotrichosis

What is Sporotrichosis?

A chronic infection that begins as a skin lesion and then involves lymphatic channels that drain the area

Describe the macroscopic appearance of Sporothrix schenckii at 25 degrees celsius in young cultures

Small and white

Describe the macroscopic morphology of Sporothrix schenckii at 25 degrees when the colony ages

Moist, wrinkled, leathery or velvety, darkening to brown/black

What organism is this? Obverse or reverse?

Sporothrix schenckii obverse

What organism is this? Obverse or reverse?

Sporothrix Schenckii reverse

Describe the macroscopic appearance of Sporothrix Schenckii at 37 degrees Celsius

Tan, smooth, yeast-like

Describe the microscopic morphology of Sporothrix Schenckii at 25 degrees Celsius

Pear-shaped conidia in rosette-like clusters

Describe the microscopic morphology of Sporothrix schenckii at 37 degrees Celsius

Oval fusiform budding cells “Cigar bodies”

What organism is this, and at what temperature?

Sporothrix schenckii at 25 degrees Celsius

What organism is this and what temperature?

Sporothrix schenckii 37 degrees Celsius