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Microbiology > Fungal & Parasitic CNS Infx > Flashcards

Fungal & Parasitic CNS Infx Flashcards

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Biology 101 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
Q

The below triad suggests…

chorioentinitis
hydrocephalus
intracranial calcification

A

congenital toxoplasmosis

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26
Q

What is the most common route of transmission for toxoplasmosis?

A

foodborne as zoitocysts

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27
Q

What are three methods of transmission for toxoplasmosis?

A

foodborne, zoonotic (oocysts), congenital, blood transfusion

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28
Q

What are the two diagnostic stages of T. gondii?

A

zoitocysts and trophozoites

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29
Q

What test for T. gondii ID measures parasite specific IgG or IgM in which population?

A

ELISA in pregnant women

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30
Q

PCR can detect T. gondii in what type of fluid?

A

amniotic

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31
Q

Is Tx for T. gondii necessary in immunocompetent patients?

A

no

32
Q

How long is the course of tx for T. gondii in AIDS patients?

A

lifelong

33
Q

The below are 4 methods of containing…

cook meat

wear gloves/handwashing after gardening

cover outdoor sandboxes

no cats/litter cleaning if pregnant

A

T. gondii

34
Q

This is a facultative protozoan found in standing water/lakes and results in rare but severe brain infx…

A

Naegleria fowleri

35
Q

What are the two distinct morphological forms of N. fowleri?

A

cyst and trophozoite

36
Q

The cyst form of N. fowleri is spore-like, and can be identified by…

A

single nucleus

37
Q

What are the 2 forms of N. fowleri’s trophozoite stage?

A

flagellate: 2 flagella

amoeboid

38
Q

What is the reproductive form of N. fowleri that is the only form found in tissue?

A

amoeboid/trophozoite form

39
Q

which form of N. fowleri is infective?

A

flagellate

40
Q

When the flagellate N. fowleri enters the nasal passages, it transforms into…

A

amoeboid form

41
Q

The amoeboid form of N. fowleri travels along ________ to the _______ to cause necrosis

A

olfactory bulbs to brain

42
Q

What structure allows the N. fowleri amoeboid to travel along the olfactory bulbs?

A

sucker apparatus

43
Q

The CNS infection that resembles bacterial meningitis caused by N. fowleri is called…

A

primary acute meningoencephalitis

44
Q

can PAM from N. fowleri infect healthy individuals or is it only problematic for immunocompromised populations?

A

healthy people

45
Q

how quickly can death occur from PAM once sxs appear?

A

2 days

46
Q

is N. fowleri transmitted person-to-person?

A

no

47
Q

A wet mount of _______ can look for motile N. fowleri amoeba…

A

CSF

48
Q

What may appear on tissue sections with N. fowleri?

A

tophozoites/atypical mononuclear cells

49
Q

What 2 findings on E. coli covered agar plates indicate N. fowleri dx?

A

clearing zones and flagellated form

50
Q

What are two main causative organisms that result in acanthamoebiasis?

A

A. castellani

A. culbertsoni

51
Q

What are two morphologic forms of acanthamoeba species?

A

trophozoite and cyst

52
Q

The trophozoite form of acanthamoeba species is infective. What differentiates it from N. fowleri?

A

spiked pseudopodia

53
Q

What structure on the cyst form of acanthamoeba renders resistance to environmental conditions?

A

3 layered wall

54
Q

_____ forms of acanthamoeba exist int he environment. They enter the human body via…

A

lower respiratory tract or ulcerated/broken skin

55
Q

What are the diagnostic forms of acanthamoeba in tissue?

A

cyst and trophozoite

56
Q

what is the infective form of acanthamoeba?

A

trophozoites

57
Q

What are the three clinical syndromes of acanthamoeba infection?

A

GAM/GAE

Ocular acanthamoebiasis

disseminated disease

58
Q

Ocular acanthamoebiasis may resemble _______. It is caused by _______

A

resemble corneal herpes

eye trauma and cyst contamination

59
Q

How long is the incubation period for GAM/GAE from acanthamoeba species?

A

weeks

60
Q

what is the mortality rate for GAM/GAE?

A

100% within 7-120 days

61
Q

how does acanthamoeba travel to the brain to cause GAM/GAE?

A

hematogenous after inhalation or wounds

62
Q

Does acanthamoeba mostly affect immunocompromised or healthy people?

A

immunocompromised

63
Q

Serum Abs for acanthamoeba can be found in ______% of otherwise healthy people?

A

50-100% (we’ve all been exposed)

64
Q

What can be observed in tissue sections when trying to identify acanthamoeba species?

A

cysts and trophozoites

65
Q

acanthamoeba keratitis is diagnosed via…

A

corneal scrapings

66
Q

GAE is dx via

A

post-mortem brain biopsy

67
Q

This is a pathogen that is related to acanthamoeba that also causes GAE

A

balamuthia mandrillaris

68
Q

what forms of B. mandrillaris are infectious?

A

trophozoite and cyst

69
Q

Do B. mandrillaris trophozoites have flagella?

A

no

binucelate w/ flat peudopodia

70
Q

B. mandrillaris enters the body via…

A

cyst inhalation or via wounds

71
Q

B. mandrillaris can be found where in the environment?

A

soil, feeds other amoeba

72
Q

can B. mandrillaris infect healthy people?

A

yes

73
Q

What other pathogen can replicate inside B. mandrillaris that confers 1000x increase in virulence?

A

legionella

74
Q

How are cysts and trophoczoites identified in B. mandrillaris?

A

tissue section

75
Q

What makes cx of B. mandrillaris difficult? What can it be co-cx with?

A

no bacterial feeding

co-cx with primate hepatic cells or human brain cells

Microbiology (13 decks)

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