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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
Naegleria fowleri has what two distinct morphological forms
1. Cyst: _single nucleate_ 2. Trophozoites 1. Flagellate (2 flagella) 2. Amoeboid
26
which form of Naegleria fowleri is the reproductive form, the only form in tissue, phagocytoses RBC and WBC, and destroys tissue
* Trophozoites -\> **Amoeboid**
27
in Naegleria fowleri, the cyst form arises from
arises from the amoeboid form in harsh conditions
28
in Naegleria fowleri, which form is the infective stage? how does it infect
1. Trophozoites -\> Flagellate form * enters nasal passages, then transforms into amoeboid form * migrates along olfactor nerve to brain * consumes cells of brain
29
Naegleria fowleri can infect what patient populations
immunocompetent patients
30
how does someone become infected with Naegleria fowleri
* 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
how is Naegleria fowleri diagnosed
* 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
DOC Naegleria fowleri
* combo * Amohotericin B * Rifampin * Miconazole
33
prevention of Naegleria fowleri
* 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
What are the two main causes of Acanthamoebiasis
* Acanthamoeba castellani * Acanthamoeba culbertsoni
35
What are the two morphological forms of Acanthamoeba
1. Trohozoite * infective stage * posses spiked pseudopodia 2. Cyst * 3 layered wall
36
how does someone become infected with Acanthamoeba
* enters through lower respiratory tract or through ulcerated or broken skin
37
Acanthamoeba causes what three clinical syndromes
1. Granulomatous Amoebic Meningoencephalitis (GAM or GAE) 2. Ocular Acanthamoebiasis Keratitis and Uveitis 3. Disseminated disease
38
describe Ocular acanthamoebiasis keratitis
* introduced by trauma to the eye followed by contamination with cysts * ulceration, intense pain, blurred vision
39
Acanthamoeba primarily affects what patient population
immunocompromised hosts
40
what does Acanthamoeba feed on in nature
* free living organism * feeds on bacteria in nature
41
how is Acanthamoeba diagnosed
* both cysts and trophozoites can be observed in tissue sections * keratitis: corneal scraping * GAE: post mortem brain biospy
42
tx: Acanthamoeba keratitis
* oral itraconazole, topical miconazole and a corticosteroid
43
tx of Acanthamoeba GAE
* pentamidine and ketoconazole
44
Balamuthia mandrillaris exists in what 2 forms
* trophozoite: no flagella * mostly binucleate * flat pseudopodia for locomotion * cyst: 3 layered wall
45
which form of Balamuthia mandrillaris is infectious
BOTH forms
46
how does Balamuthia mandrillaris enter the body
* inhalation of cysts or through wounds * may form a skin lesion or migrate to the brain
47
clinical presentation * facial paralysis * difficulty swallowing * sz * paralysis * double vision
Balamuthia mandrillaris
48
where is Balamuthia mandrillaris normally found
* soil * preys on other amoeba
49
Balamuthia mandrillaris can affect what patient population
can infect healthy persons
50
Balamuthia mandrillaris allows what bacteria to replicate within it
* legionella pneuophila * increases virulence of parasite
51
how is Balamuthia mandrillaris diagnosed
* 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
tx Balamuthia mandrillaris
* combo x 2 weeks * flucanazole * sulfadiazine * pentamidine * then azithromycin for at least 3 weeks

micro test 3 (7 decks)

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