Melanized (Dematiaceous) Fungi Flashcards
Dark or black hyphae
Melanized
Reverse of colony is dark or black (front may vary)
Dematiaceous
Infection w/ black molds
Phaeohyphomycosis
Chronic subcutaneous skin condition w/ cauliflower-like growths; always caused by dematiaceous fungi
Chromomycosis/chromoblastomycosis
Chronic granulomatous infection; usually at the site of inoculation; swollen tissue w/ draining sinus tracts (grainy discharge); invasive into the bone
Mycetoma
Inflammation of the cornea of the eye caused by many different bacteria, yeast, molds, parasites
Keratitis
Mycetoma agent of infection by bacteria (GP bacilli); branching, filamentous
Actinomycotic
Agent of mycetoma by fungi; often dematiaceous fungi (BLACK granules); less often non-dematiaceous (WHITE granules)
Eumycotic
(“Copper pennies”) in tissue is diagnostic for chromoblastomycosis
Medlar/sclerotic/muriform bodies
Which genera are considered melanized (dematiaceous) fungi?
- Fonsecaea
- Phialophora
- Cladosporium
- Cladophialophora bantiana
- Exophiala
- Curvularia
- Alternaria
- Bipolaris
- Stachybotrys
Most common organism that causes tinea nigra
Hortaea werneckii
Most common organism that causes black piedra
Piedraia hortae
Most common organism that causes chromoblastomycosis
Slow-growing fungi
- Fonsecaea
- Phialophora
- Cladophialophora
Most common organism that causes white grain mycetoma
Pseudallescheria boydii, Fusarium, and others
Most common organism that causes black grain mycetoma
Exophiala and others
Most common organism that causes actinomycotic mycetoma
- Partially acid-fast: Nocardia, Rhodococcus, and others
- Nonacid-fast: Streptomyces, Actinomadura
Most common organism that causes cerebral phaeohyphomycosis
Cladophialophora bantiana (leading cause in immunocompotent individual) - Bacterial brain infections are MUCH more common
Clinical manifestations involved in tinea nigra
- Dark patches on skin, usually palms of hands, soles of feet
- Can resemble malignant melanoma
Clinical manifestations involved in black piedra
Black nodules on hair (any body part)
Clinical manifestations involved in chromomycosis
- Cauliflower-like growths
- Sclerotic bodies (“copper pennies”) in tissue
Clinical manifestations involved in mycetoma
- 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)
Clinical manifestations involved in cerebral phaeohyphomycosis
?
Two dematiaceous fungi that are “rapid” growers
- Curvularia
- Alternaria
What is the criteria for “slow” growers and “rapid” growers?
- Rapid: <7 days
- Slow: may take weeks to grow (10-14 days)
How is man usually infected?
Accidentally infected from traumatic injury, inhalation in immunocompromised people (usually involve lower extremities)
What is the gold standard for diagnosing melanized (dematiaceous) fungi?
Culture
What are considered cutaneous (superficial) infections?
- Tinea nigra
- Black piedra
- White piedra
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?
- Chromoblastomycosis/chromomycosis
- Mycetoma
Where are chromomycosis infections most commonly seen worldwide?
Tropic or subtropic climates (S. America) but cases have been seen in the U.S.
What is diagnostic for chromoblastomycosis?
Sclerotic bodies (“copper pennies”) in tissue (aka medlar/muriform bodies)
What is important to culture in a mycetoma?
Biopsy (culture the grains)
Mycotic keratitis is often caused by what?
Traumatic injury, contact lens use, surgery
Cladosporium vs. Cladophialophora
- Which one grows at 40°C?
Cladophialophora
Cladosporium vs. Cladophialophora
- Which is a contaminant and which is pathogenic?
- Cladosporium is a contaminant
- Cladophialophora is pathogenic (grows at body temp)
Which dematiaceous fungi has four types of conidia growth?
Fonsecaea
- Cladosporium
- Acrotheca
- Phialophora
- Rhinocladiella
Has flask-shaped phialides w/ flared collarettes
Phialophora
Chains of elliptical conidia, branching conidiophores
Cladosporium
Very long chains of conidia, very little branching
Cladophialora
Pointed conidiophores w/ oval conidia that grow along the sides of the conidiophores
Exophiala
Jagged conidiophores; conidia are 4-celled w/ swollen central cell (boomerang shaped, TRANSVERSE SEPTA ONLY)
Curvularia
Drumstick/snowshoe macroconidia w/ LONGITUDINAL and TRANSVERSE SEPTA
Alternaria
Twisted conidiophores where conidia are attached; conidia are oval and multicelled (“peapods”)
Bipolaris
What is the major concern over molds causing “Sick Building Syndrome” (i.e., Stachybotrys)
It has an affinity for high cellulose (wallboard)
What steps can be taken to prevent mold overgrowth in homes?
- 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
