5.14 Fungi

Question 1

the colony morphology of yeasts is ___________ whereas molds are ____________

Answer 1

smooth, creamy; powdery, fluffy

Question 2

what is the morphology of dimorphic fungi under the microscope

Answer 2

either smooth and creamy or fluffy and powdery depending on the form taken

Question 3

usually dimorphic fungi are _________ in the environment and ___________ in the body

Answer 3

mold; yeast

Question 4

all fungal infections are ________ infections that require heavy/low burden

Answer 4

opportunist; heavy

Question 5

what is the characteristic infection that develops from fungi

Answer 5

granulomatous (chronic)

Question 6

fungal infections are relatively common/uncommon

Answer 6

uncommon

Question 7

gram stain can only be used on ______ fungi, and the other stains that can be used on all fungi are (4)

Answer 7

yeast; PAS, Wrights, Silver, Diff-Quik

Question 8

what type of mount must be done to visualize fungi and why

Answer 8

10% KOH wet mount; to get rid of keratin in host tissues

Question 9

what must be added to culture to grow fungi; do yeasts or molds grow faster

Answer 9

Sabouraud dextrose agar; yeasts grow faster

Question 10

what 3 immunological tests can be used to ID fungi

Answer 10

ELISA, DTH, immuno-diffusion

Question 11

how do we treat or control fungal infections

Answer 11

• decrease the predisposition or challenge
• topical antifungals
• systemic antifungals (limited)

Question 12

what do we call agents of ringworm

Answer 12

dermatophytes

Question 13

T/F ringworm is zoonotic

Answer 13

T

Question 14

what do dermatophytes infect

Answer 14

keratinized epithelium of skin, hair, nails

Question 15

what is a very common dermatophytes in cows

Answer 15

Trichophyton verrucosum

Question 16

what type of dermatophytes infects dogs and cats

Answer 16

cats: Microsporum canis
dogs: Microsporum canis and microsporum gypseum

Question 17

describe the classic ringworm lesion

Answer 17

slowly expanding area of alopecia and desquamated epithelium; central area of hair regrowth; inflammed edge

Question 18

all ringworm is _____________

Answer 18

superficial

Question 19

ringworm is highly contagious due to ______________

Answer 19

arthrospores

Question 20

what causes predisposition to ringworm

Answer 20

young animals; poor nutrition; humidity; rubbing; low UV

Question 21

what dermatophyte fluoresces

Answer 21

Microsporum canis

Question 22

how long does it take to culture ringworm

Answer 22

7-10 days

Question 23

how do we treat and control ringworm

Answer 23

topical or systemic treatments; isolation; treating bedding; decontaminating environment; vaccines

Question 24

what animals have a ringworm vaccine

Answer 24

cats and cattle

Question 25

is Aspergillus fumigatus fast or slow growing

Answer 25

fast

Question 26

where is Aspergillus fumigatus

Answer 26

ubiquitous; mold on bread, cheese, rotten fruit, etc.

Question 27

how does A. fumigatus invade the body

Answer 27

in damaged tissues along blood vessels

Question 28

T/F Aspergillus fumigatus causes either superficial or systemic infection

Answer 28

T

Question 29

what influences the type of disease caused by Aspergillus fumigatus

Answer 29

host predisposition, challenge or both

Question 30

what is characteristic of mycotic abortion caused by Aspergillus fumigatus

Answer 30

placentitis and lesions on the fetus skin (neck and shoulders)

Question 31

what are some diseases caused by aspergillus

Answer 31

- mycotic abortion (cows, horses) - air sacculitis - granulomatous pneumonia (birds) - rumenitis - keratitis (horses) - sinusitis (dogs, horses) - gluttaral pouch mycosis - allergic lung disease

Question 32

how can we prevent and treat aspergillus infections

Answer 32

prevent by lowering predisposition; treat with antifungals and surgical removal of contamination/granulomatous inflammation

Question 33

T/F Candida albicans is zoonotic

Answer 33

F

Question 34

is C. albicans gram positive or negative

Answer 34

positive

Question 35

where is C. albicans

Answer 35

in flora of mouth, intestine urogenital tract

Question 36

T/F candida albicans is an opportunist

Answer 36

T

Question 37

describe the types (invasive vs non-invasive) of infections caused by C. albicans

Answer 37

usually superficial but can invade locally using pseudohyphae

Question 38

where can thrush occur

Answer 38

mouth, tongue, proventriculus, stomach

Question 39

what predisposes an animal to developing thrush

Answer 39

immunocompromised, antibiotics, moisture, iatrogenic during mastitis treatment, steroids

Question 40

T/F Candida albicans and Aspergillus fumigatus grow at the same rate (1-2 days to culture)

Answer 40

T

Question 41

how do we treat and prevent Candida albicans

Answer 41

prevent predisposition; treat with antifungals (local or systemic)

Question 42

what is a common cause of otitis externa and dermatitis in dogs (ears and skin)

Answer 42

Malassezia pachydermatitis

Question 43

what is the footprint shaped yeast

Answer 43

Malassezia pachydermatitis

Question 44

we treat systemic fungal infections with fungistatic or fungicidal drugs

Answer 44

cidal

Question 45

what causes blastomycosis

Answer 45

Blastomyces dermatitidis

Question 46

what is special about blastomyces dermatitidis

Answer 46

dimorphic; very large yeast in tissue

Question 47

where is blastomyces dermatitidis located

Answer 47

high leaf-litter

Question 48

what types of dogs are predisposed to blastomycosis

Answer 48

young male hunting dogs (inhale the spores during the fall)

Question 49

what is the pathogenesis of blastomycosis (B. dermatitidis)

Answer 49

dogs inhale the spores in the fall -> spores germinate in the lungs, forming yeasts -> immunosuppression -> granulomatous pneumonia -> dissemination systemically -> local ulcerative ischemic lesions and granulomatous inflammation

Question 50

because Blastomyces dermatitidis is a slow growing mold, it may take ______ to see the disease develop

Answer 50

1-2 months

Question 51

what are some ways to diagnose blastomycosis

Answer 51

culture, serology, direct demo

Question 52

what are the 2 agents of cryptococcosis

Answer 52

C. neoformans, C. gattii

Question 53

what is special about C. neoformans and C. gattii

Answer 53

dimorphic and encapsulated yeast

Question 54

C. neoformans is associated with ____________________ and causes disease in ____________ individuals whereas C. gattii is associated with ___________________ and causes disease in ______________ individuals

Answer 54

bird manure (pigeons); immunocompromised; leaf litter; healthy

Question 55

what does C. neoformans cause

Answer 55

granulomatous inflammation of the URT and brain; rarely pneumonia

Question 56

what is the pathogenesis of C. neoformans

Answer 56

inhaled; granulomas in the nasal sinuses; reaches the CNS directly or via blood

Question 57

what diseases is C. neoformans associated with

Answer 57

FIV/FeLV

Question 58

how do we diagnose C. neoformans

Answer 58

direct demo; PCR; culture; capsular antigen demo