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Microbiology > E3- Fungal and Parasitic CNS infections > Flashcards

E3- Fungal and Parasitic CNS infections Flashcards

1
Q

What is the habitat of Cryptococcus neoformans?

A

Natural reservoirs- soil, bird droppings

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2
Q

What is typically required for Cryptococcus neoformans to cause an infection?

A

Underlying immunodeficiency prior to infection

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3
Q

What type of disease does Cryptococcus neoformans cause?

A

Starts as a skin or pulmonary infection and can lead to meningoencephalitis (fatal)

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4
Q

What can be seen on india ink of Cryptococcus neoformans?

A

Encapsulated yeast

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5
Q

What are the 3 pathogenicity factors of Cryptococcus neoformans?

A
  • Capsule
  • Diphenol oxidase that forms melanin from phenol containing substrates
  • Able to grow at 37 degrees C
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6
Q

How is Cryptococcus neoformans transmitted?

A

Inhalation of yeast cells

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7
Q

Is Cryptococcus neoformans communicable?

A

NO

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8
Q

What form of Cryptococcus can cause more extensive infections?
How can you differentiate this species from Cryptococcus neoformans.?

A

Cryptococcus gatti

Culture on canavanine glycine bromothymol blue medium (C. gatti will turn blue)

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9
Q

How can Cryptococcus neoformans be dx?

A
  • Samples of CSF (examined w/ india ink)
  • Culture on Bird Seed agar/Caffeic acid medium
  • Serology (detection of capsule antigen in CSF/serum by latex agglutination)
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10
Q

What type of stain should be used to examine Cryptococcus neoformans?

A

India ink

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11
Q

What type of plates should be used to culture Cryptococcus neoformans?

A

Bird Seed agar/Caffeic acid medium

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12
Q

What is typically required for Toxoplasma gondii to cause an infection?

A

Underlying immunodeficiency prior to infection

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13
Q

What patient populations can Toxoplasma gondii cause severe complicattions?

A
  • Immunocompromised

- Newly infected pregnant women

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14
Q

What is the infective form of Toxoplasma gondii?

A

Cysts

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15
Q

Which type of trophozoite form of Toxoplasma gondii is considered the actively replicating form?

A

Tachyzoite-acute disease

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16
Q

Which type of trophozoite form of Toxoplasma gondii is considered the slowly replicating form?

A

Bradyzoite-chronic disease

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17
Q

Which type of cyst form of Toxoplasma gondii contains bradyzoites?

A

Zoitocysts

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18
Q

Which type of cyst form of Toxoplasma gondii is seen in seen in cats and is the sexual stage of the parasites lifecycle?

A

Oocysts

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19
Q

What is the triad of congenital toxoplasmosis?

A
  • Chorioretinitis
  • Hydrocephalus
  • Intracranial calcifications
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20
Q

How is Toxoplasma gondii transmitted?

A
  • Food borne (usually zoitocysts)
  • Zoonotic (oocysts)
  • Congenital
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21
Q

What forms of Toxoplasma gondii are seen on dx?

A

Zoitocysts and trophozoite forms

22
Q

How is Toxoplasma gondii dx?

A
  • ELISA
  • PCR
  • Isolated from CSF
23
Q

What is the habitat of Naegleria fowleri?

A

Soil and fresh water (facultative environmental protozoan)

24
Q

What form of Naegleria fowleri is infectious?

A

Flagellate (trophozoite)

25
Q

What form of Naegleria fowleri is reproductive and feeds on bacteria?

A

Amoeboid (trophozoite)

26
Q

What form of Naegleria fowleri is formed in tissue, causing destruction and phagocytosis of RBCs and WBCs?

A

Amoeboid (trophozoite)

27
Q

What is the life-cycle of Naegleria fowleri?

A
  • Infective flagellate form enters the nasal passage and then transforms into the amoeboid form
  • It migrates along the olfactory nerve to the brain
  • Causes severe necrosis of the olfactory bulb and brain tissue through sucker apparatus
28
Q

How is Naegleria fowleri transmitted?

A

Entry through the nasal passageway

29
Q

What type of infection does Naegleria fowleri cause?

A

Primary Acute Meningoencephalitis

30
Q

Does a Naegleria fowleri infection require an immunocompromised host?

A

No

31
Q

Is Naegleria fowleri spread person-to-person or via contaminated drinking water?

A

No

32
Q

There is increasing incidence of Naegleria fowleri infections via what?

A

Neti pots

33
Q

How is Naegleria fowleri dx?

A
  • Drop CSF on plate with E. coli
  • Look for clearing zones
  • Pick up amoeba and place in distilled water
  • Look for flagellated form
34
Q

Is chlorine effect in killing Naegleria fowleri?

A

No

35
Q

What is the infective stage of Acanthamoeba?

A

Trophozoite

36
Q

What is seen in the trophozoite form of Acanthamoeba?

A

Spiked pseudopodia

37
Q

How is Acanthamoeba transmitted?

A

Enters through the lower respiratory tract or ulcerated/broken skin

38
Q

What are the 3 clinical syndromes caused by Acanthamoeba?

A
  • Granulomatous Amoebic Meningoencephalitis
  • Ocular Acanthamoebiasis Keratitis and Uveitis
  • Disseminated disease
39
Q

How does Acanthamoeba cause a Granulomatous Amoebic Meningoencephalitis infection?

A

Hematogenous route to the brain

40
Q

How does Acanthamoeba cause an Ocular Acanthamoebiasis Keratitis and Uveitis infection?

A

Introduced by trauma to the eye, followed by contamination with cysts

41
Q

What form of Acanthamoeba can be seen in tissue?

A

Both trophozoite and cysts

42
Q

How is Acanthamoeba dx?

A
  • Tissue sample
  • Keratitis cornea scrapings
  • Postmortem brain biopsy
43
Q

What is not efficient in dx Acanthamoeba?

A

Examining CSF

44
Q

What type of infection can Balamuthia mandrillaris cause?

A

Granulomatous Amoebic Meningoencephalitis

45
Q

What form of Balamuthia mandrillaris is infectious?

A

Both the trophozoite and cyst forms are infectious

46
Q

What is seen in the trophozoite form of Balamuthia mandrillaris?

A

Binucleate

Flat pseudopodia

47
Q

How is Balamuthia mandrillaris transmitted?

A

Enters through the lower respiratory tract or ulcerated/broken skin

48
Q

What geographic location is Balamuthia mandrillaris most commonly found?

A 
Southern states (California)
Latin America
49
Q

What does Balamuthia mandrillaris allow to replicate within it? Why?

A

Legionella pneumophilia

Increases its virulence

50
Q

What form of Balamuthia mandrillaris can be seen in tissue?

A

Both trophozoite and cysts

51
Q

How is Balamuthia mandrillaris dx?

A

Only co-cultured with primate hepatic cells or human brain cells

52
Q

Why can Balamuthia mandrillaris not be cultured easily?

A

It does not feed on bacteria

Microbiology (23 decks)

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