Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
18 Cards in this Set
- Front
- Back
|
Is cryptococcus a dimorph?
|
No. It can have hyphal forms but it is not a classic dimorph
|
|
|
What staining technique should be used to ID cryptococcus
|
india ink
|
|
|
how is cryptococcous classified
|
basidiomycete
|
|
|
Describe sexual development in C. neoformans
|
a and alpha mating type fuse and develop into a dikaryotic filament. The filament then forms a basidium and spores develop
|
|
|
What are species of Cryptococcus
|
C. neoformans var grubii and var neoformans
C. gattii |
|
|
Where is C. neoformans found
|
worldwide, virtually ubiquitous
|
|
|
Where is C. gattii found
|
equatorial regions
|
|
|
How does infection with C. neoformans occur
|
inhalation of spores and/or yeast into lungs, dissemination from lungs into CNS
(less commonly needle sticks and organ transplantation it is not contagious person to person or animal to person) |
|
|
What populations are at risk for Crypto meningitis
|
AIDS, organ transplant, Chemo
|
|
|
T/F the skin is a site of primary cryptococcus infection
|
false, skin presenations are usually the result of dissemination
|
|
|
T/F crypto can survive in phagocytes
|
true
|
|
|
Which immune cells are important for fighting crypto infections
|
CD4, CD8 T cells, NK cells
|
|
|
Are there preventative strategies for crypto infection
|
none other than environmental avoidance which is difficult
|
|
|
List 4 virulence determinants for crypto
|
1. growth at 37
2. capsule formation 3. laccase/melanin production 4. mating type alpha |
|
|
Describe the role of melanin in cryptococcus virulence
|
1. protective against UV
2. scavage free radicals prevent oxidative damage, facilliate in vivo survival 3. there may be more substrates for melanin production in the brain which may facilitate CNS tropism |
|
|
Describe the role of the capusule in crypto virulence
|
-production increases with characteristics of the host environment including increased temp, high CO2 and low iron
-masks other epitopoes facilitating immune evasion -harder to phagocytose |
|
|
What features of crypto spores support the hypothesis that the spores are infectious particles
|
-small
-kill mice -get phagocytosed and germinate in the naieve macrophage |
|
|
Describe crypto spore germination in macrophages
|
spores are actively phagocytosed and will germinate in naive macrophages. Macrophage activation by T cells prevents spore germination
|
