mycology; dematiaceous fungi

Question 1

infection with dematiaceous fungi usually results from

Answer 1

traumatic inoculation and subcutaneous infection

Question 2

chromoblastomycosis is

Answer 2

is a chronic, indolent, granulomatous fungal disease caused by the transcutaneous inoculation of propagules (conidia and/or mycelia) from several species of melanized fungi

Question 3

chromoblastomycosis is found in

Answer 3

tropical and subtropical regions, and commonly includes infection of the lower legs and feet, lesions are pigmented and often “warty” or sclerotic

Question 4

Genii that cause chromomycosis

Answer 4

Fonsecaea
Phialophora
Cladosporium
Exophiala

Question 5

what is mycetoma and what causes it?

Answer 5

Mycetoma is a chronic, progressive local infection caused by fungi or bacteria and involving the feet, upper extremities, or back. Symptoms include tumefaction and formation of sinus tracts with granular pus, sometimes called “madura foot”

Question 6

What is phaeohyphomycosis?

Answer 6

Phaeohyphomycosis refers to infections caused by many kinds of dark, melanin-pigmented dematiaceous fungi. It is distinguished from chromoblastomycosis and mycetoma by the absence of specific histopathologic findings. Clinical syndromes include invasive sinusitis, sometimes with bone necrosis, as well as subcutaneous nodules or abscesses, keratitis, lung masses, osteomyelitis, mycotic arthritis, endocarditis, brain abscess, and disseminated infection.

Question 7

Genii that cause phaeohyphomycosis

Answer 7

Bipolaris, Curvularia, Alternaria, Exophiala, Phialophora, Exserohilum

Question 8

Fonsecaea pedrosi and compacta identification

Answer 8

brown/olive/black velvety colonies
grow in 12-14 days
display a rhinocladiella (bottle brush) or acrotheca (coat rack) conidia shape
hyphae are regular in diameter, septate, and yellow/brown pigmented

Question 9

Phialophora verrucosum identification

Answer 9

wooly to cotton-y olive green to brown colonies, “mushroom-y”
7-20 days to grow
short vase-like phialides come off hyphae laterally with stacks of elliptical shaped conidia
hyphae are dematiaceous and septate

Question 10

Cladosporium carrionii ID

Answer 10

velvet grey w/ a dark apron
reverse is green/black
10-14 days to grow
lemon shaped conidia on top of thin dark-staining phialides
slender, septate darkly pigmented hyphae

Question 11

exophiala

Answer 11

downy to velvet colonies that are yellow/green on the from and jet black on reverse
10-14 days to mature
oval conidia in clusters surround long straight phialides that terminate in a delicate tip
“3 stacked rectangles w/ cascading conidia”

Question 12

Bipolaris ID

Answer 12

grey/brown w/ radial rugae and a white apron
reverse is black
3-5 days to mature
“bipolaris” comes from germ tubes that form from both ends of conidium in saline after 4/6 hours
common cause of sinusitis
cylindrical oval gently curving conidia divided by transverse septa
hyphae are polymorphous

Question 13

Curvularia

Answer 13

radial dark green to black rugae
suede like texture
white apron
3-5 days
boomerang shaped conidia
multi-celled macroconidia w/ transverse septa

Question 14

Alternaria

Answer 14

dark grey to black colony w/ a white outer growth apron
3-5 days
drumstick shaped conidia w/ brown pigment

Question 15

Exserhilum

Answer 15

cottony wooly grey to brown, light brown apron
reverse is dark brown
3-5 days to grow
macroconidia are long, pencil shaped, segmented by transverse septa
rod-like protrusions exit from the hilar cell
cause of fungal meningitis