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Fungal & Parasitic CNS Infx Flashcards

1
Q

The MC etiology of cryptococcosis is _____ found in what population?

A

crytococcus neoformans in immunocompetent hosts

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2
Q

What is the reservoir of cryptococcus neoformans?

A

Natural: soil, bird droppings

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3
Q

Describe the progression of cryptococcosis when dessicated yeast cells are inhaled…

A

skin or pulm infx to meningoencephalitis

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4
Q

Cryptococcus neoformans has A-D serotypes. Which is the most frequent type?

A

A > D and A/D

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5
Q

On microscopy, you see encapsulated yeasts on india ink. what does this indicate?

A

cryptococcus neoformans

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6
Q

you notice creamy/mucoid colonies on saboroud’s dextrose agar or potato dextrose agar…what pathogen?

A

cryptococcus neoformans

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7
Q

Besides the capsule, what are two pathogenic factors of cryptococcus neoformans?

A

diphenol oxidase (laccase)

growth at 37 C

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8
Q

Diphenol oxidase forms what substance from phenol containing substrates?

A

melanin

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9
Q

What media can identify diphenol oxidase?

A

bird seed agar, caffeic acid medium

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10
Q

the yeast form of cryptococcus neoformans prefers to grow/replicate where in the human body?

A

CSF

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11
Q

are cryptococcal disease communicable?

A

no

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12
Q

Pulmonary cryptococcosis can have what clinical manifestations?

A

asx, flu-like sxs, cavitation

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13
Q

Disseminated cryptococcosis infx can have what manifestations?

A

meningitis, crytococcoma, skin lesions

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14
Q

What cause of cryptococcosis has more extensive/severe infx?

A

C. gatti

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15
Q

What two species can cause cryptococcosis?

A

C. gatti, C. neoformans

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16
Q

Dx of cryptococcosis can occur via what four methods?

A

Sample, direct exam, cx, serology

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17
Q

This test for cryptococcosis can detect capsule antigen…

A

latex agglutination test (serology)

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18
Q

Cx for non-mixed cryptococcosis should occur on what agar?

A

sabouraud dextrose agar (SDA) or potato dextrose agar (PDA)

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19
Q

mixed cryptococcosis infx can be cultured on…

A

birdseed agar

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20
Q

Canavanine glycine bromothymol blue (CGB) agar can help differentiate the causative agent of cryptococcosis. A blue agar indicates which pathogen? Yellow agar indicates…

A

C. gatti = blue

c. neoformans = yellow

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21
Q

What populations can have severe complications from toxoplasma infx?

A

immunocompromised

pregnant women newly infected

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22
Q

What are the two morphological forms of T. gondii?

A

trophozoites

cysts

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23
Q

What are the two types of T. gondii trophozoites? which one is more efficiently cleared by immune system?

A

tachyzoite - acute dz, efficient immune clearance

bradyzoite - chronic dz

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24
Q

What are the two types of cysts of T. gondii? which one is in cells, and which one is the sexual stage in cats?

A

Zoltocyst (contains bradyzoites) in cells

oocyst: sexual stage in cats

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25
The below triad suggests... chorioentinitis hydrocephalus intracranial calcification
congenital toxoplasmosis
26
What is the most common route of transmission for toxoplasmosis?
foodborne as zoitocysts
27
What are three methods of transmission for toxoplasmosis?
foodborne, zoonotic (oocysts), congenital, blood transfusion
28
What are the two diagnostic stages of T. gondii?
zoitocysts and trophozoites
29
What test for T. gondii ID measures parasite specific IgG or IgM in which population?
ELISA in pregnant women
30
PCR can detect T. gondii in what type of fluid?
amniotic
31
Is Tx for T. gondii necessary in immunocompetent patients?
no
32
How long is the course of tx for T. gondii in AIDS patients?
lifelong
33
The below are 4 methods of containing... cook meat wear gloves/handwashing after gardening cover outdoor sandboxes no cats/litter cleaning if pregnant
T. gondii
34
This is a facultative protozoan found in standing water/lakes and results in rare but severe brain infx...
Naegleria fowleri
35
What are the two distinct morphological forms of N. fowleri?
cyst and trophozoite
36
The cyst form of N. fowleri is spore-like, and can be identified by...
single nucleus
37
What are the 2 forms of N. fowleri's trophozoite stage?
flagellate: 2 flagella amoeboid
38
What is the reproductive form of N. fowleri that is the only form found in tissue?
amoeboid/trophozoite form
39
which form of N. fowleri is infective?
flagellate
40
When the flagellate N. fowleri enters the nasal passages, it transforms into...
amoeboid form
41
The amoeboid form of N. fowleri travels along ________ to the _______ to cause necrosis
olfactory bulbs to brain
42
What structure allows the N. fowleri amoeboid to travel along the olfactory bulbs?
sucker apparatus
43
The CNS infection that resembles bacterial meningitis caused by N. fowleri is called...
primary acute meningoencephalitis
44
can PAM from N. fowleri infect healthy individuals or is it only problematic for immunocompromised populations?
healthy people
45
how quickly can death occur from PAM once sxs appear?
2 days
46
is N. fowleri transmitted person-to-person?
no
47
A wet mount of _______ can look for motile N. fowleri amoeba...
CSF
48
What may appear on tissue sections with N. fowleri?
tophozoites/atypical mononuclear cells
49
What 2 findings on E. coli covered agar plates indicate N. fowleri dx?
clearing zones and flagellated form
50
What are two main causative organisms that result in acanthamoebiasis?
A. castellani | A. culbertsoni
51
What are two morphologic forms of acanthamoeba species?
trophozoite and cyst
52
The trophozoite form of acanthamoeba species is infective. What differentiates it from N. fowleri?
spiked pseudopodia
53
What structure on the cyst form of acanthamoeba renders resistance to environmental conditions?
3 layered wall
54
_____ forms of acanthamoeba exist int he environment. They enter the human body via...
lower respiratory tract or ulcerated/broken skin
55
What are the diagnostic forms of acanthamoeba in tissue?
cyst and trophozoite
56
what is the infective form of acanthamoeba?
trophozoites
57
What are the three clinical syndromes of acanthamoeba infection?
GAM/GAE Ocular acanthamoebiasis disseminated disease
58
Ocular acanthamoebiasis may resemble _______. It is caused by _______
resemble corneal herpes eye trauma and cyst contamination
59
How long is the incubation period for GAM/GAE from acanthamoeba species?
weeks
60
what is the mortality rate for GAM/GAE?
100% within 7-120 days
61
how does acanthamoeba travel to the brain to cause GAM/GAE?
hematogenous after inhalation or wounds
62
Does acanthamoeba mostly affect immunocompromised or healthy people?
immunocompromised
63
Serum Abs for acanthamoeba can be found in ______% of otherwise healthy people?
50-100% (we've all been exposed)
64
What can be observed in tissue sections when trying to identify acanthamoeba species?
cysts and trophozoites
65
acanthamoeba keratitis is diagnosed via...
corneal scrapings
66
GAE is dx via
post-mortem brain biopsy
67
This is a pathogen that is related to acanthamoeba that also causes GAE
balamuthia mandrillaris
68
what forms of B. mandrillaris are infectious?
trophozoite and cyst
69
Do B. mandrillaris trophozoites have flagella?
no binucelate w/ flat peudopodia
70
B. mandrillaris enters the body via...
cyst inhalation or via wounds
71
B. mandrillaris can be found where in the environment?
soil, feeds other amoeba
72
can B. mandrillaris infect healthy people?
yes
73
What other pathogen can replicate inside B. mandrillaris that confers 1000x increase in virulence?
legionella
74
How are cysts and trophoczoites identified in B. mandrillaris?
tissue section
75
What makes cx of B. mandrillaris difficult? What can it be co-cx with?
no bacterial feeding co-cx with primate hepatic cells or human brain cells

Microbiology (13 decks)

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