Melanized (Dematiaceous) Fungi

Question 1

Dark or black hyphae

Answer 1

Melanized

Question 2

Reverse of colony is dark or black (front may vary)

Answer 2

Dematiaceous

Question 3

Infection w/ black molds

Answer 3

Phaeohyphomycosis

Question 4

Chronic subcutaneous skin condition w/ cauliflower-like growths; always caused by dematiaceous fungi

Answer 4

Chromomycosis/chromoblastomycosis

Question 5

Chronic granulomatous infection; usually at the site of inoculation; swollen tissue w/ draining sinus tracts (grainy discharge); invasive into the bone

Answer 5

Mycetoma

Question 6

Inflammation of the cornea of the eye caused by many different bacteria, yeast, molds, parasites

Answer 6

Keratitis

Question 7

Mycetoma agent of infection by bacteria (GP bacilli); branching, filamentous

Answer 7

Actinomycotic

Question 8

Agent of mycetoma by fungi; often dematiaceous fungi (BLACK granules); less often non-dematiaceous (WHITE granules)

Answer 8

Eumycotic

Question 9

(“Copper pennies”) in tissue is diagnostic for chromoblastomycosis

Answer 9

Medlar/sclerotic/muriform bodies

Question 10

Which genera are considered melanized (dematiaceous) fungi?

Answer 10

• Fonsecaea
• Phialophora
• Cladosporium
• Cladophialophora bantiana
• Exophiala
• Curvularia
• Alternaria
• Bipolaris
• Stachybotrys

Question 11

Most common organism that causes tinea nigra

Answer 11

Hortaea werneckii

Question 12

Most common organism that causes black piedra

Answer 12

Piedraia hortae

Question 13

Most common organism that causes chromoblastomycosis

Answer 13

Slow-growing fungi

• Fonsecaea
• Phialophora
• Cladophialophora

Question 14

Most common organism that causes white grain mycetoma

Answer 14

Pseudallescheria boydii, Fusarium, and others

Question 15

Most common organism that causes black grain mycetoma

Answer 15

Exophiala and others

Question 16

Most common organism that causes actinomycotic mycetoma

Answer 16

• Partially acid-fast: Nocardia, Rhodococcus, and others

- Nonacid-fast: Streptomyces, Actinomadura

Question 17

Most common organism that causes cerebral phaeohyphomycosis

Answer 17

Cladophialophora bantiana (leading cause in immunocompotent individual)
- Bacterial brain infections are MUCH more common

Question 18

Clinical manifestations involved in tinea nigra

Answer 18

• Dark patches on skin, usually palms of hands, soles of feet
• Can resemble malignant melanoma

Question 19

Clinical manifestations involved in black piedra

Answer 19

Black nodules on hair (any body part)

Question 20

Clinical manifestations involved in chromomycosis

Answer 20

• Cauliflower-like growths

- Sclerotic bodies (“copper pennies”) in tissue

Question 21

Clinical manifestations involved in mycetoma

Answer 21

• Swollen tissue w/ draining sinus tracts (purulent, grainy discharge)
• Sclerotia (also known as granules or grains) → color of grains can signify agent of infection (black vs. white)

Question 22

Clinical manifestations involved in cerebral phaeohyphomycosis

Answer 22

?

Question 23

Two dematiaceous fungi that are “rapid” growers

Answer 23

• Curvularia

- Alternaria

Question 24

What is the criteria for “slow” growers and “rapid” growers?

Answer 24

• Rapid: <7 days

- Slow: may take weeks to grow (10-14 days)

Question 25

How is man usually infected?

Answer 25

Accidentally infected from traumatic injury, inhalation in immunocompromised people (usually involve lower extremities)

Question 26

What is the gold standard for diagnosing melanized (dematiaceous) fungi?

Answer 26

Culture

Question 27

What are considered cutaneous (superficial) infections?

Answer 27

- Tinea nigra - Black piedra - White piedra

Question 28

Subcutaneous infections are usually the result of a traumatic inoculation to the deep layers of the skin. What are two examples of this type of infection?

Answer 28

- Chromoblastomycosis/chromomycosis | - Mycetoma

Question 29

Where are chromomycosis infections most commonly seen worldwide?

Answer 29

Tropic or subtropic climates (S. America) but cases have been seen in the U.S.

Question 30

What is diagnostic for chromoblastomycosis?

Answer 30

Sclerotic bodies ("copper pennies") in tissue (aka medlar/muriform bodies)

Question 31

What is important to culture in a mycetoma?

Answer 31

Biopsy (culture the grains)

Question 32

Mycotic keratitis is often caused by what?

Answer 32

Traumatic injury, contact lens use, surgery

Question 33

Cladosporium vs. Cladophialophora | - Which one grows at 40°C?

Answer 33

Cladophialophora

Question 34

Cladosporium vs. Cladophialophora | - Which is a contaminant and which is pathogenic?

Answer 34

- Cladosporium is a contaminant | - Cladophialophora is pathogenic (grows at body temp)

Question 35

Which dematiaceous fungi has four types of conidia growth?

Answer 35

Fonsecaea - Cladosporium - Acrotheca - Phialophora - Rhinocladiella

Question 36

Has flask-shaped phialides w/ flared collarettes

Answer 36

Phialophora

Question 37

Chains of elliptical conidia, branching conidiophores

Answer 37

Cladosporium

Question 38

Very long chains of conidia, very little branching

Answer 38

Cladophialora

Question 39

Pointed conidiophores w/ oval conidia that grow along the sides of the conidiophores

Answer 39

Exophiala

Question 40

Jagged conidiophores; conidia are 4-celled w/ swollen central cell (boomerang shaped, TRANSVERSE SEPTA ONLY)

Answer 40

Curvularia

Question 41

Drumstick/snowshoe macroconidia w/ LONGITUDINAL and TRANSVERSE SEPTA

Answer 41

Alternaria

Question 42

Twisted conidiophores where conidia are attached; conidia are oval and multicelled ("peapods")

Answer 42

Bipolaris

Question 43

What is the major concern over molds causing "Sick Building Syndrome" (i.e., Stachybotrys)

Answer 43

It has an affinity for high cellulose (wallboard)

Question 44

What steps can be taken to prevent mold overgrowth in homes?

Answer 44

- Use 1c bleach w/ 1 gallon water - Find/repair water leaks, air condition or dehumidifiers, ventilation in the bathrooms and kitchens, clean regularly, don't carpet the bathrooms