5.14 Fungi Flashcards
the colony morphology of yeasts is ___________ whereas molds are ____________
smooth, creamy; powdery, fluffy
what is the morphology of dimorphic fungi under the microscope
either smooth and creamy or fluffy and powdery depending on the form taken
usually dimorphic fungi are _________ in the environment and ___________ in the body
mold; yeast
all fungal infections are ________ infections that require heavy/low burden
opportunist; heavy
what is the characteristic infection that develops from fungi
granulomatous (chronic)
fungal infections are relatively common/uncommon
uncommon
gram stain can only be used on ______ fungi, and the other stains that can be used on all fungi are (4)
yeast; PAS, Wrights, Silver, Diff-Quik
what type of mount must be done to visualize fungi and why
10% KOH wet mount; to get rid of keratin in host tissues
what must be added to culture to grow fungi; do yeasts or molds grow faster
Sabouraud dextrose agar; yeasts grow faster
what 3 immunological tests can be used to ID fungi
ELISA, DTH, immuno-diffusion
how do we treat or control fungal infections
- decrease the predisposition or challenge
- topical antifungals
- systemic antifungals (limited)
what do we call agents of ringworm
dermatophytes
T/F ringworm is zoonotic
T
what do dermatophytes infect
keratinized epithelium of skin, hair, nails
what is a very common dermatophytes in cows
Trichophyton verrucosum
what type of dermatophytes infects dogs and cats
cats: Microsporum canis
dogs: Microsporum canis and microsporum gypseum
describe the classic ringworm lesion
slowly expanding area of alopecia and desquamated epithelium; central area of hair regrowth; inflammed edge
all ringworm is _____________
superficial
ringworm is highly contagious due to ______________
arthrospores
what causes predisposition to ringworm
young animals; poor nutrition; humidity; rubbing; low UV
what dermatophyte fluoresces
Microsporum canis
how long does it take to culture ringworm
7-10 days
how do we treat and control ringworm
topical or systemic treatments; isolation; treating bedding; decontaminating environment; vaccines
what animals have a ringworm vaccine
cats and cattle
is Aspergillus fumigatus fast or slow growing
fast
where is Aspergillus fumigatus
ubiquitous; mold on bread, cheese, rotten fruit, etc.
how does A. fumigatus invade the body
in damaged tissues along blood vessels
T/F Aspergillus fumigatus causes either superficial or systemic infection
T
what influences the type of disease caused by Aspergillus fumigatus
host predisposition, challenge or both
what is characteristic of mycotic abortion caused by Aspergillus fumigatus
placentitis and lesions on the fetus skin (neck and shoulders)
what are some diseases caused by aspergillus
- mycotic abortion (cows, horses)
- air sacculitis
- granulomatous pneumonia (birds)
- rumenitis
- keratitis (horses)
- sinusitis (dogs, horses)
- gluttaral pouch mycosis
- allergic lung disease
how can we prevent and treat aspergillus infections
prevent by lowering predisposition; treat with antifungals and surgical removal of contamination/granulomatous inflammation
T/F Candida albicans is zoonotic
F
is C. albicans gram positive or negative
positive
where is C. albicans
in flora of mouth, intestine urogenital tract
T/F candida albicans is an opportunist
T
describe the types (invasive vs non-invasive) of infections caused by C. albicans
usually superficial but can invade locally using pseudohyphae
where can thrush occur
mouth, tongue, proventriculus, stomach
what predisposes an animal to developing thrush
immunocompromised, antibiotics, moisture, iatrogenic during mastitis treatment, steroids
T/F Candida albicans and Aspergillus fumigatus grow at the same rate (1-2 days to culture)
T
how do we treat and prevent Candida albicans
prevent predisposition; treat with antifungals (local or systemic)
what is a common cause of otitis externa and dermatitis in dogs (ears and skin)
Malassezia pachydermatitis
what is the footprint shaped yeast
Malassezia pachydermatitis
we treat systemic fungal infections with fungistatic or fungicidal drugs
cidal
what causes blastomycosis
Blastomyces dermatitidis
what is special about blastomyces dermatitidis
dimorphic; very large yeast in tissue
where is blastomyces dermatitidis located
high leaf-litter
what types of dogs are predisposed to blastomycosis
young male hunting dogs (inhale the spores during the fall)
what is the pathogenesis of blastomycosis (B. dermatitidis)
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
because Blastomyces dermatitidis is a slow growing mold, it may take ______ to see the disease develop
1-2 months
what are some ways to diagnose blastomycosis
culture, serology, direct demo
what are the 2 agents of cryptococcosis
C. neoformans, C. gattii
what is special about C. neoformans and C. gattii
dimorphic and encapsulated yeast
C. neoformans is associated with ____________________ and causes disease in ____________ individuals whereas C. gattii is associated with ___________________ and causes disease in ______________ individuals
bird manure (pigeons); immunocompromised; leaf litter; healthy
what does C. neoformans cause
granulomatous inflammation of the URT and brain; rarely pneumonia
what is the pathogenesis of C. neoformans
inhaled; granulomas in the nasal sinuses; reaches the CNS directly or via blood
what diseases is C. neoformans associated with
FIV/FeLV
how do we diagnose C. neoformans
direct demo; PCR; culture; capsular antigen demo
