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Fungal and Parasitic CNS infections Flashcards

1
Q

What is the most likely pathogen for cryptococcosis infection?

A

Cryptococcus neoformans

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2
Q

Cryptococcus neoformans is an endogenous or exogenous infection?

A

Exogenous

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3
Q

Inhalation of dessicated yeast cells from a natural reservoir (soil, bird droppings) will lead to what infection?

A

cryptococcosis

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4
Q

If cryptococcosis travels to the brain from initial skin or pulmonary infection, what is the result?

A

Meningoencephalitis SX: Fever, HA, stiff neck, AMS

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5
Q

What are 2 serotypes (A, B, C, D) are associated w/ C. neoformans?

A

A, D and A/D *C. gattii = serotypes B and C

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6
Q

When viewing Cryptococcus neoformans under a microscope will you see encapsulated or non-encapsulated yeast?

A

Encapsulated

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7
Q

What ink will help you view the encapsulated yeast of Cryptococcus neoformans?

A

India Ink

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8
Q

What are the 3 pathogenicity factors of Cryptococcus neoformans?

A
  1. Capsule (evades phagocytosis) 2. Diphenol oxidase (a laccase enzyme) forms melanin from phenol containing substrates 3. Ability to grow at 37˚C
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9
Q

What infection is initiated by inhalation of yeast cells that is especially problematic for IMC pts?

A

Cryptococcus neoformans

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10
Q

Does the yeast form of C. neoformans prefer blood or CSF?

A

CSF

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11
Q

T or F: All cases of meningoencephalitis from C. neoformans infection are fatal?

A

TRUE

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12
Q

Are cryptococcal diseases communicable?

A

No

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13
Q

The following are clinical manifestations of what disease? 1. Pulmonary - asymptomatic/flu-like/cavitation 2. Disseminated meningitis 3. Skin lesions

A

Cryptococcosis

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14
Q

Will C. gattii or C. neoformans lead to more extensive infections?

A

C. gattii *Found in immunocompetent hosts

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15
Q

Will C. gattii or C. neoformans turn blue on canavanine glycine bromothymol blue medium?

A

C. gattii

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16
Q

What is the pathogen that causes toxoplasmosis?

A

Toxoplasma gondii

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17
Q

Toxoplasma gondii can lead to severe complications in what 2 populations?

A
  1. IMC 2. Women newly infected in pregnancy *Toxoplasma gondii is asx in immunocompetent pts
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18
Q

Which trophozoite form of T. gondii, tachyzoite (acute) or bradyzoite (chronic), more efficiently cleared by the immune system?

A

Tachyzoite

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19
Q

Is the tachyzoite (acute) or bradyzoite (chronic) form of T. gondii the actively proliferating form?

A

Tachyzoite Bradyzoite = slowly replicating

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20
Q

T. gondii has two distinct morphologically distinct forms. What are they?

A
  1. Trophzoite (tachyzoite & bradyzoite) 2. Cysts (zoitocyst, oocyst)
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21
Q

Are trophozoites or cysts infective for T. gondii?

A

Cysts

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22
Q

What animal is the host for the sexual stage (oocyst) of the T. gondii’s sexual stage?

A

Cats *Oocysts can remain infectious for up to 1 year in soil

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23
Q

Chorioretinitis, hydrocephalous, and intracranial calcifications are the triad of sx suggestive of what form of toxoplasmosis?

A

Congenital toxoplasmosis *Congenital cases result in more severe damage (blindness, epilepsy, developmental delays).

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24
Q

Is toxoplasmosis transmitted via direct humans contact or foodborne?

A

Food-borne transmission (usually zoitocysts)

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25
Infection with toxoplasmosis is highest in what types of climates?
Hot and humid
26
What are the tests can be used to DX Cryptococcosis (C. gattii or C. neoformans)?
Samples taken from CSF, sputum, aspiration from skin lesion Direct exam via India Ink Culture: - SDA or PDA (sabouraud dextrose or potato dextrose agar) - Birdseed agar if mixed infection - Grow at 37˚C - Grown on canavanine glycine bromethyl blue medium Serology: Detection of capsule antigen in CSF and serum by latex agglutination test
27
The zoitocysts (tissue cyst) of T. gondii contains the tachyzoite or the bradyzoite?
Bradyzoite
28
Fever, myalgia, blurred vision and mild flu sx are sx of congenital toxoplasmosis or post natal toxoplasmosis?
Post natal toxoplasmosis
29
In what states of T. gondii infection can it be diagnosed?
Zoitocysts and trophozoites
30
What preventative measures will help prevent T gondii infection? (4)
1. Cook meat thoroughly 2. Wear gloves during and wash hands after gardening 3. Keep outdoor sandboxes covered 4. Pregnant women should NOT clear liter box or adopt new cats
31
The cyst form of N. fowleri arises from the amoeboid under harsh conditions. How many nuclei does it have?
1 (single nucleate)
32
The flagellate form of N. fowleri arises based on changes in ionic environment or lack of nutrients. This process occurs in minutes. How many flagella does it have?
2 \*Flagella will grow in response to an environment that it doesn't like so that it can move to an environment that has nutrients where it will then change to ameboid form
33
The amoeboid form phagocytes what cell types in humans (2) that leads to the destruction of what? (1)
1. RBCs and WBC 2. Destroys tissues
34
Once a pt infected w/ N. fowleri becomes symptomatic they can die within what time frame?
2 days - 2 wks (quick incubation period)
35
Is chlorine effective against N. fowleri?
No
36
How many layers make up the wall of the acanthamoeba cyst?
3 layered wall Yes, resistant to environmental conditions
37
What are the pathogens (2) that cause granulomatous amoebic meningoencephalitis (GAM)?
acanthamoeba and balamuthia mandrillais
38
Will sx manifest quickly or slowly with granulomatous amoebic meningoencephalitis (GAM)?
Slowly (enters via wound/respiratory tract --\> blood --\> brain = long incubation period)
39
How does acanthamoebiasis keratitis and uveitis manifest?
1. Trauma to eye 2. Contaminated w/ cysts SX: Corneal ulceration, intese pain, blurred vision, FB sensation
40
Is examination of CSF useful in the dx of acanthamoeba?
No
41
Does the trophozoite form for b. mandrillaris have a flagella?
No, only flat pseudopodia for locomotion
42
How many nuclei does the trophozoite form of b. mandrillaris have?
2 (binucleate)
43
How may layered walls does the cyst for b. mandrillaris have?
3 (same as acanthamoebas)
44
Where is b. mandrillaris found in the environment?
In the soil
45
Geographically, where is b. mandrillaris mostly found?
Latin America
46
B. mandrillaris allows what other pathogen to replicate within it? What does this result in?
B. mandrillaris allows legionella pneumophila to replicate within it.
47
How do you control b. mandrillaris? (2)
1. Avoid swimming in stagnant ponds 2. Wear gloves while gardening
48
Where is Naegleria fowleri found?
Soil and standing fresh water (facultative environmental)
49
What does infection with Naegleria fowleri result in?
Primary Acute Meningoencephalitis (PAM) (rare brain infection → death w/i 2 days)
50
What are the 2 distinct morphological forms of Naegleria fowleri?
Cyst-single nucleate and trophozoite (alternates between flagellate and amoeboid forms)
51
Which form of Naegleria fowleri arises from the ameboid form (harsh conditions)?
Cyst-single nucleate
52
Which form of Naegleria fowleri arises based on change in ionic environment/ lack of nutrients?
Trophozoite- flagellate
53
Which form of Naegleria fowleri is the reproductive form, the only form that feeds on bacteria, and ultimately destroys tissue?
Trophozoite- amoeboid
54
What is the only infective form of N. fowleri?
Flagellate
55
How does N. fowleri (trophozoite form) result in brain damage?
Enters via nasal passage Migrates along olfactory nerve to brain
56
Pt presents w/ fever, stiff neck, HA, CNS inflammation, and AMS. Also hx of confusion, hallucinations, and seizures. What infecting organism should you be concerned about?
N. fowleri
57
Can N. fowleri be spread from person to person or contracted from drinking contaminated water?
No
58
During what time of year and what locations in the US is N. fowleri most common?
Summer months in southern states
59
Infection with N. fowleri will display what on E.coli covered agar plates?
Clearing zones and flagellated form (confirmation) - Once amoeba isolated in clearing zone, it is placed in distilled water where it will turn to flagellate form. This is conformation for N. fowleri \* This process is timely and often too slow for disease progression
60
The following are ways to help control and prevent infections with what disease/ pathogen? - Avoid stagnant ponds - Do not disturb sediment - Only use distilled/ purified water in Neti pots
N. fowleri
61
What are the causative agents of acanthamoebiasis (2)?
A. castellani and A. culbertsoni
62
What morphological form of A. castellani and A. culbertsoni are considered infective and possess spiked pseudopodia?
Trophozoite
63
What morphological form of A. castellani and A. culbertsoni are resistant to environmental conditions?
Cyst
64
What are the 3 clinical syndromes associated with Acanthamoeba spp.?
Granulomatous Amoebic Meningocephalitis (GAM or GAE) Ocular Acanthamoebiasis Keratitis and Uveitis Disseminated disease
65
What clinical syndrome associated with Acanthamoeba spp. involves a spread from the wound → blood → brain and has a long incubation period?
Granulomatous Amoebic Meningocephalitis (GAM or GAE)
66
What is the mortality rate of Granulomatous Amoebic Meningocephalitis (GAM or GAE)?
100%
67
Pt presents with blurred vision and pain with a foreign body sensation. They have a hx of trauma to the eye. What syndrome/ pathogen should you be concerned about?
Granulomatous Amoebic Meningocephalitis (GAM or GAE) caused by Acanthamoeba spp.
68
Although Acanthamoeba spp. is widely found, what must you have for infection?
Break/ulceration in the skin
69
How is infection with Acanthamoeba spp. diagnosed?
Cysts and trophozoites observed in tissues (Corneal scrapings if keratitis, post mortem brain bx if GAE)
70
How is infection with Acanthamoeba spp. controlled?
Gloves while gardening, properly clean lesions
71
What organism is infectious in both the trophozoite and cyst forms and can cause Granulomatous Amoebic Meningocephalitis?
Balamuthia mandrillaris
72
Which form of Balamuthia mandrillaris lacks flagella, is mostly binucleate and has flat pseudopodia for locomotion?
Trophozoite
73
How does infection via Balamuthia mandrillaris occur?
Inhalation of cysts or through ulcerated/broken skin (can infect healthy or IMC)
74
Pt presents w hx of facial paralysis, difficulty swallowing, seizures, paralysis, and double vision. What infecting organism should you be concerned about?
Balamuthia mandrillaris
75
What factor increases the virulence of Balamuthia mandrillaris?
Replication of Legionella pneumophilia within parasite
76
What disease can only be co-cultured with primate hepatic cells or human brain cells and is therefore easily missed?
Balamuthia mandrillaris
77
How is infection via Balamuthia mandrillaris controlled?
Avoid swimming in stagnant ponds and gloves while gardening

Micro I (9 decks)

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