Dimorphic Fungi and Monomorphic Yeasts

Question 1

dimorphic fungi cause what kind of infections

Answer 1

systemic; often acquired by inhilation

Question 2

what makes a fungus dimorphic

Answer 2

growth as a yeast at body temp and fungus at room temo

Question 3

in general, dimorphic species look

Answer 3

big white and fluffy, should never be opened in open air

Question 4

Blastomyces dermatiditis ID

Answer 4

cottony white matures to a dark brown
1-4 weeks to mature
“lollipop conidia”
in tissue, round to oval buds with a broad base, figure 8
blastomycosis

Question 5

Coccidiodes immitis ID

Answer 5

grey to cottony white colonies
5-14 days
barrel shaped alternating arthroconidia “empty cells”
spherules with endospores microscopically
“valley fever”
endemic to SW US

Question 6

Histoplasma capsulatum ID

Answer 6

white to brown colonies, fluffy,
2-4 weeks
tuberculate or spiky macroconidia
yeast forms are seen in monocytes, microscopically clusters of spherical conidia
endemic to ohio river valley
asso/w bird droppings

Question 7

Paracoccidiodes brasiliensis

Answer 7

white colony browns with age
5-7 days
septate hyphae with clamydoconidia on the ends and middle of the hyphae
yeast have multiple buds like a ships wheel
causes chronic granulomas
central and south america

Question 8

Penicillium marneffei

Answer 8

blue green powdery colony with a red pigment in agar
4-7 days
brush like conidiophores
looks like histoplasma but has a distinctive intracytoplasmic transverse septum
common in immunocompromised

Question 9

sporothrix schenckii

Answer 9

room temp is white colony but slowly turns black
7-10 days
rosette conidia
oval/cigar shaped yeast cells
“rose gardener’s disease”

Question 10

candida albicans

Answer 10

pasty white colonies with star burst feet
psudeohyphae emerge from yeast bud/blastoconidium
germ tube positive
cornmeal agar will make tight clusters of small uniform blastoconidia appear

Question 11

candida dublinesis

Answer 11

In HIV pts
germ tube +
cannot grow at 45 C but C. albicans does
shaggy on bird seed agar as opposed to smooth

Question 12

C. galabrata

Answer 12

decreases susceptibility to fluconazole
microscopically, regular-sized yeast cells that are compactly arranged
“small, spherical, regular in size, and compactly arranged.”

Question 13

C. tropicalis

Answer 13

problem in leukemia patients

Question 14

C. auris

Answer 14

emerging MDR pathogen

Question 15

Cryptococcus neoformans

Answer 15

mucoid colonies (capsule)
dark brown on bird seed agar
spherical, irregular in size, and separated by capsular material. Occasional buds may be observed
in tissue: irregular-sized spherical yeast cells surrounded by distinct capsular material

Question 16

trichosporon

Answer 16

rectangular arthroconidia
“rabbit ears”
piedra

Question 17

geotrichum

Answer 17

3-5 days
white and fuzzy colony
barrel shaped conidia
hockey stick arthroconidia

Question 18

rhodotorula

Answer 18

pink to orange pigment
urease +

Question 19

saccharomyces

Answer 19

grey white pasty colony
red-acid fast
2-4 days