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micro test 3 > Lect 18 > Flashcards

Lect 18 Flashcards

1
Q

Cryptococcosis from Cryptococcus neoformans affects what patient population

A
  • immunocompromised
    • AIDS, lymphoma
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2
Q

Cryptococcus gattii affects what patient population

A

found in immunocompetent hosts

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3
Q

Cryptococcus neoformans natural reservoir

A
  • soil
  • bird droppings
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4
Q

how does someone get infected with Cryptococcus neoformans

A
  • inhalation of dessicated yeast cells
    • most often starts as skin or pulmonary infection then progresses to CNS
  • cryptoococcal disease are not communicable!
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5
Q

what critical condition can Cryptococcus neoformans cause

A

meningoencephalitis

  • yeast form prefers CSF
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6
Q

Cryptococcus neoformans

  • capsule?
  • serotypes?
A
  • encapsulated
  • serotypes A-D (most frequently A)
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7
Q

Cryptococcus neoformans has what that allows them to form melanin from phenol containing substrates

A

Diphenol Oxidase (Laccase)

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8
Q

List virulence factors of Cryptococcus neoformans

A
  1. capsule
  2. Diphenol oxidase - form melanin
  3. ability to grow at 37 C
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9
Q

Name the two clinical manifestations of infection with Cryptococcus neoformans

A
  1. pulmonary
    • asymptomatic/flu-like/cavitation
  2. Disseminated
    • meningitis, skin lesions, cryptococcoma
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10
Q

how is cryptococcosis diagnosed

A
  1. samples: CSF, sputum, skin lesion -> india ink
  2. growth on CGB medium will differentiate between gattii and neoformans
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11
Q

tx of Cryptococcosis

A
  • amphotericin B (+flucytosine)
  • life long fluconazole prophylazid following primary tx in AIDS patients
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12
Q

Exserohilum rostratum is commonly found where

A
  • black mold of the soil and plants
  • found in warm, humid climates
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13
Q

what was the predominant pathogen in the multistate outbreak of fungal meningitis associated with contaminated steroids

A

Exserohilum rostratum

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14
Q

Toxoplasma gondii affects what patient populations

A
  • asymptomatic in immunocompetent host
  • severe complications in immunocompromised hosts and women newly infected in pregnancy
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15
Q

Toxoplasma gondii is present in what two distinct morphological forms? These forms also can be divded into subcategories. name this too.

A
  1. Trophozoites
    • Tachyzoite: acute disease; actively proliferating
    • Bradyzoite: chronic disease; slowly replicating
  2. Cysts
    • Zoitocyst: tissue cytst that contains bradyzoites
    • Oocyst: sexual stage in cats
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16
Q

what is the host for sexual stage of Toxoplasma gondii life cycle

A

cats

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17
Q

which form of Toxoplasma gondii is the infective stage

A

cysts

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18
Q

what are the triad of symptoms suggesting congenital toxoplasmosis

A
  1. chorioretinitis
  2. hydrocephalus
  3. intracranial calcifications
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19
Q

how does transmission of Toxoplasma gondii occur

A
  • no person-to-person contact
  • occurs through
    • foodborne
    • zoonotic
    • congenital
  • **pregnant women should not clean liter box or adopt new cats
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20
Q

What stages of Toxoplasma gondii life cycle are diagnostic

A
  • Zoitocysts
  • Trophozoites
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21
Q

how is Toxoplasma gondii diagnosed

A
  • ELISA to measure parasite specific IgG or IgM in pregnant women
  • PCR
  • parasites can be isolated from CSF
22
Q

Tx of Toxoplasma gondii

A
  • not necessary in immunocompetent
  • in immunocompromised
    • pyrimethamine and sulfadiazine (does not completely remove parasite)
    • AIDS patients require lifelong therapy
23
Q

What is Naegleria fowleri? where is it normally found

A
  • facultative environmental protozoan
  • found in soil and fresh water
    • ​swimming pools, streams, ponds
24
Q

infection with Naegleria fowleri results in

A

Primary acute meningoencephalitis (PAM)

  • rapidly fatal: death can occur within 2 days of becoming symptomatic
  • fever, stiff neck, HA, AMS, confusion, hallucinations, sz
25
Q

Naegleria fowleri has what two distinct morphological forms

A
  1. Cyst: single nucleate
  2. Trophozoites
    1. Flagellate (2 flagella)
    2. Amoeboid
26
Q

which form of Naegleria fowleri is the reproductive form, the only form in tissue, phagocytoses RBC and WBC, and destroys tissue

A
  • Trophozoites -> Amoeboid
27
Q

in Naegleria fowleri, the cyst form arises from

A

arises from the amoeboid form in harsh conditions

28
Q

in Naegleria fowleri, which form is the infective stage? how does it infect

A
  1. Trophozoites -> Flagellate form
    • enters nasal passages, then transforms into amoeboid form
    • migrates along olfactor nerve to brain
    • consumes cells of brain
29
Q

Naegleria fowleri can infect what patient populations

A

immunocompetent patients

30
Q

how does someone become infected with Naegleria fowleri

A
  • not spread person-to-person
  • can’t be contracted from drinking contaminated water
  • HAS to go through nasal passages
    • increased incidence through use of tap water in Neti pots
31
Q

how is Naegleria fowleri diagnosed

A
  • CSF
  • wet mount for motile amoeba
  • clearing zones on E-coli covered agar plates
    • plates coated with E-coli
    • drop of CSF on plate
    • look for clearing zones, pick up amoeba and place in distilled water
      • if you see flagellated form => confirmation
32
Q

DOC Naegleria fowleri

A
  • combo
    • Amohotericin B
    • Rifampin
    • Miconazole
33
Q

prevention of Naegleria fowleri

A
  • avoid swimming in stagnant ponds
  • keep head above water
  • use only distilled/purified water in Neti pots
  • Salination occasionally works as a decontaminant, chlorine is ineffective
34
Q

What are the two main causes of Acanthamoebiasis

A
  • Acanthamoeba castellani
  • Acanthamoeba culbertsoni
35
Q

What are the two morphological forms of Acanthamoeba

A
  1. Trohozoite
    • infective stage
    • posses spiked pseudopodia
  2. Cyst
    • 3 layered wall
36
Q

how does someone become infected with Acanthamoeba

A
  • enters through lower respiratory tract or through ulcerated or broken skin
37
Q

Acanthamoeba causes what three clinical syndromes

A
  1. Granulomatous Amoebic Meningoencephalitis (GAM or GAE)
  2. Ocular Acanthamoebiasis Keratitis and Uveitis
  3. Disseminated disease
38
Q

describe Ocular acanthamoebiasis keratitis

A
  • introduced by trauma to the eye followed by contamination with cysts
  • ulceration, intense pain, blurred vision
39
Q

Acanthamoeba primarily affects what patient population

A

immunocompromised hosts

40
Q

what does Acanthamoeba feed on in nature

A
  • free living organism
    • feeds on bacteria in nature
41
Q

how is Acanthamoeba diagnosed

A
  • both cysts and trophozoites can be observed in tissue sections
  • keratitis: corneal scraping
  • GAE: post mortem brain biospy
42
Q

tx: Acanthamoeba keratitis

A
  • oral itraconazole, topical miconazole and a corticosteroid
43
Q

tx of Acanthamoeba GAE

A
  • pentamidine and ketoconazole
44
Q

Balamuthia mandrillaris exists in what 2 forms

A
  • trophozoite: no flagella
    • mostly binucleate
    • flat pseudopodia for locomotion
  • cyst: 3 layered wall
45
Q

which form of Balamuthia mandrillaris is infectious

A

BOTH forms

46
Q

how does Balamuthia mandrillaris enter the body

A
  • inhalation of cysts or through wounds
  • may form a skin lesion or migrate to the brain
47
Q

clinical presentation

  • facial paralysis
  • difficulty swallowing
  • sz
  • paralysis
  • double vision
A

Balamuthia mandrillaris

48
Q

where is Balamuthia mandrillaris normally found

A
  • soil
  • preys on other amoeba
49
Q

Balamuthia mandrillaris can affect what patient population

A

can infect healthy persons

50
Q

Balamuthia mandrillaris allows what bacteria to replicate within it

A
  • legionella pneuophila
    • increases virulence of parasite
51
Q

how is Balamuthia mandrillaris diagnosed

A
  • cysts and trophozoites can be identified in tissue sections
  • cannot be cultured easily
  • only co-cultured with primate hepatic cells or human brain cells
52
Q

tx Balamuthia mandrillaris

A
  • combo x 2 weeks
    • flucanazole
    • sulfadiazine
    • pentamidine
  • then azithromycin for at least 3 weeks

micro test 3 (7 decks)

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