Term
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Definition
| General term to describe unicellular fungi |
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Term
| What is the most frequent pathogen of the genus Candida? |
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Definition
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Term
| What is the regular habitat of Candida? |
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Definition
| Mucosal surface commensal, esp. GI & urogenital tracts |
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Term
| Describe the shape of Candida. |
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Definition
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Term
| What does Candida require for growth? |
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Definition
- Facultative
- Most are fermentative
- Grows at 37 degrees C
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Term
| What does Candida produce in serum at 37C and cornmeal agar? |
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Definition
- Germ tubes in serum (37C)
- Hyphae, pseudohyphae, & chlamydospores on cornmeal agar
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Term
| What is Candida albicans resistant to? |
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Definition
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Term
| What are hyphal forms of Candida albicans associated with? |
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Definition
| Tissue invasion & more severe disease |
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Term
| What can Candida ablicans cause in pigs and what are the signs? |
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Definition
- Thrush in oral cavity
- Signs:
- Thick, pasty exudate
- Thickened, inflamed mucosa
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Term
| Describe the shape of Malassezia pachydermatitis. |
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Definition
- Thick walled, bottle-shaped yeast
- Budding from tubular, flask-shaped cell & collarette visible at base
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Term
| Where does Malassezia pachydermatitis grow? |
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Definition
- Commensals on skin of animals
- Associated with sebaceous glands (lipophillic)
- Grows at 37C
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Term
| What is Malassezia pachydermatitis susceptible to? |
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Definition
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Term
| Does Malassezia pachydermatitis produce pseudohyphae? |
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Definition
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Term
| What is the only pathogenic species of the genus Cryptococcus? |
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Definition
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Term
| What is Cryptococcus neoformans environmental habitat? |
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Definition
- Pigeon droppings (uses the creatinine)
- Eucalyptus forests
- Proliferates in alkaline, high nitrogen, high salt evironments
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Term
| Describe the shape of Cryptococcus neoformans. |
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Definition
- Large round to oval, budding yeast
- Prominent mucopolysaccharide capsule in vivo
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Term
| What are Cryptococcus neoforman's growth requirements? |
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Definition
- Grows at 37C
- Aerobic
- Non-fermentative
- Urease positive
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Term
| What is Cryptococcus neoformans susceptible to? |
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Definition
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Term
| What are two virulence factors of C. neoformans? |
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Definition
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Term
| What stimulates C. neoformans capsule production? |
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Definition
| Water, nitrogen, bicarbonate, carbon dioxide, & iron limiting conditions |
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Term
| How does the capsule protect C. neoformans? |
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Definition
- Collapses & protects yeast from dehydration in arid environments
- Reduced size is favorable for inhalation and deposition in respiratory tract
- Suppresses cellular immune response
- Inhibits phagocytosis
- Activates alternate complement pathway (can produce complement depletion)
- Poor immunogen (can induce tolerance)
- Reduces respiratory burst in phagocytes
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Term
| How is melanin produced by C. neoformans? |
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Definition
- Production inducible by substrate
- Catalyzed by enzyme phenoloxidase (abundant in brain)
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Term
| What is the function of melanin with C. neoformans? |
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Definition
- Scavenger of reactive oxygen intermediates
- Protects cells from fungicidal effects of UV light
- May interfere with lymphoproliferation & TNF (alpha) production
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Term
| What are some characterisitics of C. neoformans disease? |
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Definition
- Environmental opportunistic pathogen
- Rare in immunocompetant humans
- Increased prevalence in individuals with T cell dysfunction
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Term
| What form of C. neoformans is most infections? |
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Definition
| Spores resulting from sexual reproduction are >100X more infectious than yeast |
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Term
| What is the usual route of entry for C. neoformans? |
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Definition
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Term
| What is the most common form of C. neoformans infection in cattle? |
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Definition
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Term
| What is the most common form of C. neoformans infection in dogs & cats? |
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Definition
Nasal infection
(can be primary local or secondary to hematogenous dissemination; lower respiratory involement is rare) |
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Term
| What does disseminated disease from C. neoformans usually involve? |
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Definition
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Term
| What are the signs of C. neoformans infection in cats? |
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Definition
- Upper respiratory (sneezing, nasal discharge)
- Polyp-like nasal masses
- SQ swelling over bridge of nose
- Cutaneous lesions
- Neurologic signs
- Ocular signs
- Anorexia, wt. loss, lymphadenopathy, etc.
- Fever uncommon
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Term
| What is the pathology of C. neoformans infection? |
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Definition
- Gelatinous masses & polyps w/ numerous organisms & minimal inflammation
- Granulomas (in immunocompetant individuals)
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Term
| How do you diagnose Cryptococcosis? |
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Definition
- Microscopic detection of encapsulated yeast (india ink prep)
- Culture (cyclohexamide susceptibility)
- Test for capsular antigen in serum or CSF (ELIZA)
- Test for serum antibody is not very useful
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Term
| How do you treat Cryptococcosis? |
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Definition
- Long term treatment until neg. serum antigen or at least 1 month after clinical resolution
- Amphoterocin B
- Azoles
- Surgical removal of masses
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Term
| How do you control Cryptococcosis? |
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Definition
- Avoid areas of high conc. of dried pigeon/bird droppings
- Avoid areas of soil disturbance (construction, mulching, logging, etc.)
- Avoid anthropogenic dispersal
- Clean & disinfect bird habitat (wet during clean-up to reduce dust)
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