Yeast and Dimorphic Fungal Infections (Ex3) Flashcards
Candida albicans
- habitat
- what is it?
- infections caused
- normal flora of mouth, intestine, and lower urogenital tract of animals and humans
- gram-pos yeast, dimorphic fungus
- Thrush: whitish-yellow hyperkeratotic lesions
- plaques in tongue, mouth, and stomach
- systemic infections: mastitis, vaginitis
- diaper rash
Malassezia pachydermatis
- morphology
- habitat
- infection caused
- thick walled, bottle shaped yeast
- commensals of skin of animals
- causes otitis externa in dogs
- causes dermatits
Morphology and Habitats of Crytpcoccus neoformans and C. gattii
- large, round to oval, budding yeast
- prominent capsule in vivo
C. neoformans: pigeon droppings
C. gattii: eucalyptus trees
Crytpococcus neoformans
- infections caused
- disease of the immunocompromised
- chronic granulomatous infection of upper respiratory tract, CNS, skin, eye, and lymph nodes
- when inhaled, granulomas of nasal sinuses
- gelatinous masses and polyps with numerous organisms and minimal inflammation
- granulomas in immunocompetent animals
Describe Thermally Dimorphic fungi
What are the members?
- single cell (yeast) or spherule at body temp
- mold forms at ambient room temp
- Histoplasma
- Blastomyces
- Coccidioides
- Sporothrix
Blastomyces dermatitidis
- disease caused
- morphology
- route of entry
- hosts
- Blastomycosis, disseminated disease common
- dimorphic fungus, large broad-based budding yeast with thick cell wall
- inhalation of spores
- dogs and humans
Histoplasma capsulatum
- disease caused
- morphology
- habitat
- transmission
- hosts
- histoplasmosis, respiratory or disseminated disease
- small, oval yeast in macrophages
- grows in dark, moist soil, covered with droppings
- route of entry inhalation, dry and dusty conditions, disturbance of soil
- dogs, cats, and humans
Coccidioides immitis
- morphology
- disease caused
- transmission
- hosts
- no yeast form: large, thick-walled spherules containing endospores
- coccidioidomycosis, chronic/active respiratory and disseminated disease similar to TB, osteomyelitis
- inhalation of arthroconidia, dry conditions and soil disturbances
- humans, dogs, and horses
Sporothrix schenkii
- morphology
- habitat
- transmission
- disease caused
- cigar shaped, elongated, pleomorphic yeast
- lives in sphagnum moss, hay, and soil
- woody, thorny plants
- entry through puncture wound
- disease usually subcutaneous, skin nodules, and regional lymphatics
What is Beta-D glucan assay?
- general screening of invasive fungal disease
- false positives and negatives may occur
What is Cryptococcus neoformans latex agglutinatin test?
- qualitative and semi-quantitative test for detection of capsular polysaccharides antigens of C. neoformans in serum or CSF
- good value
What are zygomycets?
- saprophytic filamentous fungi
- hyphae are broad, thin-walled, irregular, non-septate, right-angle branching asexual spores
- produced in a sporangium
What is hyaline fungus?
- saprophytic filamentous fungi
- hyphae are narrow, thick-walled, parallel, septate, acute angle branching asexual spores
- produced on fruiting structures called conidia
- have rapid growth
What is phaeoid/dematiaceous fungus?
- saprophytic filamentous fungi
- hyphae are narrow, thick-walled, parallel, septate, acute angle branching asexual spores
- contain melaninsome and may produce yeast forms
Aspergillus
- type of fungus
- how does it cause infection?
- hyaline fungus, so fast growing
- invades damaged tissue along blood vessels
What types of infections does Aspergillus cause?
- avian respiratory infections
- canine and equine nasal/sinus/guttural pouch infections
- abortion in ruminants
- colonization of airspaces
- allergic responses
- abscesses in brain, liver, or kidney
- disseminated infections
What predisposes an animal to an Aspergillus infection?
- stress
- concurrent disease
- poor diet
- prolonged antibiotic therapy
- poor husbandry
Describe Mycotic rumenitis
- aspergillus infection
- following rumen acidosis, fungi is resistant to acid, so the acid damages mucosa
Describe Chronic sinusitis in dogs
- aspergillus infection
- follows inhalation of molds
Describe Mycotic Keratitis
- aspergillus infection
- corneal abrasion by straw in horses
- infection of damaged cornea with mold
Prototheca
- what is it?
- habitat
- achlorophyllous algae
- in warm, nutrient-rich, aqueous environments
What are two species of Prototheca, and what types of infections do they cause?
P. zopfii: disseminated disease in dogs, mastitis in cattle, cutaneous disease in cats and humans
P. wickerhamii: cutaneous disease in cats and humans
What general infections/clinical signs does Prototheca cause?
- focal ulcerations of mucosal and skin surfaces
- bloody diarrhea, ocular disease, CNS signs, cutaneous lesions
Oomycetes
- what is it?
- name two species
- water molds
- Pythium insidiosum: swamp cancer, florida horse leech, kunkers
- Lagenidium spp.
What kind of infections do oomycetes cause?
- cutaneous and GI diseases in dogs
- cutaneous disease in horses, cats, and humans
- humans: arteritis, keratitis, periorbital cellulitis, cutaneous/subQ lesions
Describe White Nose Sydnrome
- emergent disease of hibernating bats
- named for white fungus Pseudogymnoascu destructans that infects skin of the muzzle, eats, and wings of bats
Describe Chytridiomycosis
- cause by Batrachochytrium dendrobatidis
- cutaneous disease of amphibians
What does Rhinosporidium cause?
nasal polyps and cutaneous cysts in mammals and birds
What does Pneumocystis cause?
pneumonia in animals with immunodeficiency
What is Encephalitozoon cuniculi?
- microsporidian parasite
- affects rabbit kidney and brain
Mycotoxins
- what are they
- major toxins
- secondary metabolites produced by fungi that are capable of causing disease and death in humans and animals
- Aflatoxins, Ergot alkaloids, Fumonisin, Ochratoxin, Zearalenone
