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Parasitology-Lab > U4.1b - Protozoans (Free-Living Amoebae) > Flashcards

U4.1b - Protozoans (Free-Living Amoebae) Flashcards

1
Q

3 Free-Living Pathogenic Amoebae

A
  1. Naegleria fowleri
  2. Acanthamoeba spp.
  3. Balamuthia mandrillaris
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2
Q

Naegleria fowleri:
family

A

Vahlkampfiidae

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3
Q

Identify the free-living amoeba:
free-living ameboflagellate
(has an ameba and flagellate form)

A

Naegleria fowleri

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4
Q

Identify the free-living amoeba:
only Naegleria species that can infect humans

A

Naegleria fowleri

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5
Q

T/F:
Naegleria fowleri is thermophobic.

A

False;
thermophilic

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6
Q

Where does Naegleria fowleri thrive?

A
  1. hot springs
  2. other warm aquatic environments
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7
Q

Naegleria fowleri:
trophozoites replicate by ________

A

promitosis

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8
Q

Identify the free-living amoeba:
Cyst found only in the environment

A

Naegleria fowleri

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9
Q

Naegleria fowleri:
4 ways of entry to body

A
  1. olfactory epithelium
  2. respiratory tract
  3. skin
  4. sinuses
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10
Q

Identify the free-living amoeba:
targets the brain tissue

A

Naegleria fowleri

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11
Q

Identify the free-living amoeba:
Trophozoites go straight to the brain

A

Naegleria fowleri

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12
Q

Naegleria fowleri:
Ameboid form:
Ameboflagellate:

A

Ameboid form: Limax-form (slug-like)
Ameboflagellate: 2 anterior flagella

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13
Q

Naegleria fowleri:
cyst shape and wall

A
  1. spherical
  2. single-walled
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14
Q

Naegleria fowleri:
trophozoite pseudopodia and motility

A
  1. blunt, loose pseudopodia
  2. directional motility
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15
Q

Naegleria fowleri:
disease manifestation and pathology

A

Primary Amebic Meningoencephalitis (PAM)

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16
Q

Identify the disease:
inflammation of meninges in the brain

A

Primary Amebic Meningoencephalitis (PAM)

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17
Q

T/F:
PAM can affect healthy people, has fast progression, and is very fatal.

A

True

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18
Q

How can PAM be acquired?

A

when swimming in:
1. contaminated pools
2. lakes
3. rivers

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19
Q

Primary Amebic Meningoencephalitis (PAM):
signs and symptoms

A
  1. headache
  2. fever
  3. nausea
  4. vomiting
  5. nuchal rigidity
  6. rhinitis
  7. lethargy
  8. olfactory problems
  9. mental status changes
  10. mental confusion
  11. coma
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20
Q

Primary Amebic Meningoencephalitis (PAM):
incubation period

A

2-3 days or 1-2 weeks

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21
Q

Primary Amebic Meningoencephalitis (PAM):
patients are usually dead after?

A

1 week

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22
Q

When diagnosed with PAM, brain has ____________

A

hemorrhaging;
has lots of WBC, especially neutrophils

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23
Q

When is PAM usually diagnosed?

A

post-mortem (after death)

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24
Q

T/F:
PAM has few cases in the Philippines (usually in US).

A

True

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25
Q

PAM:
virulence factors

A
  1. presence of amebostomes (food cups)
  2. used to attach to the brain
  3. releases enzymes (phospholipases) to destroy brain tissue
  4. cytopathic effect on host tissues
    • secretion of lytic enzymes
    • membrane pore-forming proteins
    • induction of apoptosis
    • direct feeding of the ameba
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26
Q

Naegleria fowleri:
laboratory diagnosis

A
  1. wet mount examination of CSF (look for trophozoite)
  2. Wright’s or Giemsa stain
  3. biopsy of tissue
  4. CSF analysis
  5. culture (bacteria seeded agar culture, modified nelson’s medium)
  6. molecular methods
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27
Q

Naegleria fowleri:
treatment and prevention

A
  1. Amphotericin B with Clotrimazole
  2. New agents: Azithromycin, Voriconazole
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28
Q

T/F:
Those who acquire Naegleria fowleri usually die after effective treatment.

A

False;
before effective treatment

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29
Q

Symptoms of PAM are indistinguishable from?

A

bacterial meningitis

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30
Q

T/F:
Antibiotics can cure PAM

A

false;
no effect

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31
Q

Naegleria fowleri:
infective stage

A

trophozoite

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32
Q

Naegleria fowleri:
parasite type

A

facultative
(with a free-living and parasitic phase)

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33
Q

Naegleria fowleri:
habitat

A
  1. lakes
  2. pools
  3. tap water
  4. air conditioning units
  5. heating units
34
Q

T/F:
Naegleria fowleri cannot survive in salt water

A

True

35
Q

Acanthamoeba spp.:
family

A

Acanthamoebidae

36
Q

Acanthamoeba species

A
  1. Acanthamoeba castellani (most common)
  2. Acanthamoeba culbertsoni
  3. Acanthamoeba hutchetti
  4. Acathamoeba polyphaga
  5. Acanthamoeba rhysoides
37
Q

Acanthamoeba spp.:
type of organism

A

aquatic

38
Q

Acanthamoeba spp.:
habitat

A

natural and artificial environments;
can survive even in contact lens solution

39
Q

Acanthamoeba spp.:
entry

A
  1. eyes
  2. nasal passages to lower RT
  3. ulcerated or broken skin
40
Q

Acanthamoeba spp.:
Possible reservoir hosts for?

A

medically important bacteria
1. Legionella spp.
2. mycobacteria
3. gram-negative bacilli (E. coli)

41
Q

Acanthamoeba spp.:
infective stage

A

both trophozoite and cyst

42
Q

Acanthamoeba spp.:
Trophozoites reproduce by?

A

binary fission

43
Q

Identify the parasite and diagnostic stage:
eats gram-negative bacteria, blue-green algae, or yeasts

A

Acanthamoeba spp. trophozoites

44
Q

Identify the parasite and diagnostic stage:
can adapt to feed on corneal epithelial cells and neurologic tissue through phagocytosis and secretion of lytic enzymes

A

Acanthamoeba spp. trophozoites

45
Q

Acanthamoeba spp.:
What happens when environmental conditions are unfavorable?

A

Trophozoites transform to cyst

46
Q

Acanthamoeba spp. trophozoite:
nucleus:
karyosome:
cytoplasm:

A

nucleus: single large nucleus
karyosome: centrally located, densely staining
cytoplasm: finely granulated

47
Q

Acanthamoeba spp. cyst:
nucleus:
karyosome:

A

nucleus: single large nucleus
karyosome: large karyosome

48
Q

Acanthamoeba spp. trophozoite:
additional structures

A
  1. acanthapodia: “thorn-like” appendages
  2. contractile vacuoles
49
Q

Acanthamoeba spp. cyst:
additional structures

A

double-walled cyst
1. outer wall: wrinkled
2. inner wall: polygonal

50
Q

Acanthamoeba spp.:
disease manifestation and pathogenesis

A
  1. Acanthamoeba Keratitis
  2. Granulomatous Amebic Encepehalitis (GAE)
  3. Cutaneous Lesions
51
Q

Identify the disease:
parasite enters through eyes

A

Acanthamoeba Keratitis

52
Q

Acanthamoeba Keratitis:
Acanthamoeba was first described in 1974 as an?

A

opportunistic ocular surface pathogen

53
Q

Acanthamoeba spp.:
associated with use of improperly disinfected soft contact lenses

A

Acanthamoeba Keratitis

54
Q

Acanthamoeba Keratitis:
symptoms

A
  1. severe ocular pain
  2. blurring vision
  3. corneal ulceration with progressive corneal infiltration
55
Q

Acanthamoeba Keratitis:
Primary amebic infection or secondary bacterial infection may lead to?

A

hypopyon formation

56
Q

Acanthamoeba Keratitis:
may lead to?

A
  1. scleritis
  2. iritis
  3. vision loss
57
Q

Acanthamoeba Keratitis:
Can be mistaken for?

A

herpes keratitis;
(to differentiate, herpes has no ocular pain)

58
Q

Stamm in 1972- documented Acanthamoeba as causative agent of human _______ using indirect fluorescence microscopy

A

GAE

59
Q

Identify the disease:
Disseminated disease in lungs and brain

A

Granulomatous Amebic Encephalitis (GAE)

60
Q

Granulomatous Amebic Encephalitis (GAE) usually occurs in?

A

immunocompromised hosts:
1. chronically ill and debilitated patients
2. those on immunosuppressive agents like chemotherapy and antirejection medications

61
Q

AIDS patients have the highest risk of acquiring this

A

Granulomatous Amebic Encephalitis (GAE)

62
Q

Granulomatous Amebic Encephalitis (GAE):
incubation period

A

10 days

63
Q

T/F:
Granulomatous Amebic Encephalitis (GAE) is chronic, slow in progression (long-standing).

A

True

64
Q

Granulomatous Amebic Encephalitis (GAE):
signs and symptoms

A
  1. destruction of brain tissue
  2. meningeal irritation
  3. fever
  4. malaise
  5. anorexia
  6. increased sleeping time
  7. severe headache
  8. mental status changes
  9. epilepsy
  10. coma
65
Q

T/F:
GAE normally results in coma or death (has poor prognosis).

A

True

66
Q

Identify the disease:
Presence of hard erythematous nodules or skin lesions

A

Cutaneous lesions

67
Q

Common in AIDS patients

A

Cutaneous lesions

68
Q

Cutaneous lesions:
parasite entry

A

through the skin

69
Q

Granulomatous Amebic Encephalitis (GAE):
laboratory diagnosis

A
  1. Usually diagnosed after death/ post-mortem
  2. AIDS patients have the highest risk of acquiring this
  3. Not as common as other infections of the CNS like Cryptococcus meningitis and toxoplasmosis
  4. Can rarely be demonstrated in Cerebrospinal fluid
70
Q

Acanthamoeba Keratitis:
laboratory diagnosis

A
  1. Epithelial biopsy or corneal scrapings (stained with Calcofluor White, then viewed under the fluorescence microscope)
    o Caused by A. castellani; A. culbertsoni; A. hutchetti; A. polyphaga or A. rhysoides
71
Q

Acanthamoeba spp. diseases:
culture

A

Culture: Cubertson’s Medium; Non-nutrient medium with Gram negative bacteria (usually Escherichia coli)

72
Q

Acanthamoeba spp. diseases:
treatment

A
  1. Fluorocystine
  2. Ketoconazole
  3. Amphotercin B
73
Q

Balamuthia mandrillaris:
family

A

Leptomyxidae

74
Q

Identify the parasite:
New species causing amebic meningoencephalitis

A

Balamuthia mandrillaris

75
Q

Identify the parasite:
Also causes Granulomatous Amebic Encephalitis (GAE)

A

Balamuthia mandrillaris

76
Q

Balamuthia mandrillaris:
Cysts have this characteristic

A

wavy appearance

77
Q

Balamuthia mandrillaris:
Trophozoites are __________.

A

branching

78
Q

Identify the parasite:
Almost the same appearance with Acanthamoeba

A

Balamuthia mandrillaris

79
Q

T/F:
Balamuthia mandrillaris: Both cysts and trophozoites can be seen in the brain (when infected)

A

True

80
Q

Other free-living ameba that causes amebic encephalitis

A
  1. Sappinia diploidea
  2. Hartmanella vermiformis
81
Q

considered now as opportunistic

A

Hartmanella vermiformis

Parasitology-Lab (8 decks)

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