U4.1b - Protozoans (Free-Living Amoebae) Flashcards
1
Q
3 Free-Living Pathogenic Amoebae
A
- Naegleria fowleri
- Acanthamoeba spp.
- Balamuthia mandrillaris
2
Q
Naegleria fowleri:
family
A
Vahlkampfiidae
3
Q
Identify the free-living amoeba:
free-living ameboflagellate
(has an ameba and flagellate form)
A
Naegleria fowleri
4
Q
Identify the free-living amoeba:
only Naegleria species that can infect humans
A
Naegleria fowleri
5
Q
T/F:
Naegleria fowleri is thermophobic.
A
False;
thermophilic
6
Q
Where does Naegleria fowleri thrive?
A
- hot springs
- other warm aquatic environments
7
Q
Naegleria fowleri:
trophozoites replicate by ________
A
promitosis
8
Q
Identify the free-living amoeba:
Cyst found only in the environment
A
Naegleria fowleri
9
Q
Naegleria fowleri:
4 ways of entry to body
A
- olfactory epithelium
- respiratory tract
- skin
- sinuses
10
Q
Identify the free-living amoeba:
targets the brain tissue
A
Naegleria fowleri
11
Q
Identify the free-living amoeba:
Trophozoites go straight to the brain
A
Naegleria fowleri
12
Q
Naegleria fowleri:
Ameboid form:
Ameboflagellate:
A
Ameboid form: Limax-form (slug-like)
Ameboflagellate: 2 anterior flagella
13
Q
Naegleria fowleri:
cyst shape and wall
A
- spherical
- single-walled
14
Q
Naegleria fowleri:
trophozoite pseudopodia and motility
A
- blunt, loose pseudopodia
- directional motility
15
Q
Naegleria fowleri:
disease manifestation and pathology
A
Primary Amebic Meningoencephalitis (PAM)
16
Q
Identify the disease:
inflammation of meninges in the brain
A
Primary Amebic Meningoencephalitis (PAM)
17
Q
T/F:
PAM can affect healthy people, has fast progression, and is very fatal.
A
True
18
Q
How can PAM be acquired?
A
when swimming in:
1. contaminated pools
2. lakes
3. rivers
19
Q
Primary Amebic Meningoencephalitis (PAM):
signs and symptoms
A
- headache
- fever
- nausea
- vomiting
- nuchal rigidity
- rhinitis
- lethargy
- olfactory problems
- mental status changes
- mental confusion
- coma
20
Q
Primary Amebic Meningoencephalitis (PAM):
incubation period
A
2-3 days or 1-2 weeks
21
Q
Primary Amebic Meningoencephalitis (PAM):
patients are usually dead after?
A
1 week
22
Q
When diagnosed with PAM, brain has ____________
A
hemorrhaging;
has lots of WBC, especially neutrophils
23
Q
When is PAM usually diagnosed?
A
post-mortem (after death)
24
Q
T/F:
PAM has few cases in the Philippines (usually in US).
A
True
25
PAM:
virulence factors
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
26
Naegleria fowleri:
laboratory diagnosis
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
27
Naegleria fowleri:
treatment and prevention
1. Amphotericin B with Clotrimazole
2. New agents: Azithromycin, Voriconazole
28
T/F:
Those who acquire Naegleria fowleri usually die after effective treatment.
False;
before effective treatment
29
Symptoms of PAM are indistinguishable from?
bacterial meningitis
30
T/F:
Antibiotics can cure PAM
false;
no effect
31
Naegleria fowleri:
infective stage
trophozoite
32
Naegleria fowleri:
parasite type
facultative
(with a free-living and parasitic phase)
33
Naegleria fowleri:
habitat
1. lakes
2. pools
3. tap water
4. air conditioning units
5. heating units
34
T/F:
Naegleria fowleri cannot survive in salt water
True
35
Acanthamoeba spp.:
family
Acanthamoebidae
36
Acanthamoeba species
1. Acanthamoeba castellani (most common)
2. Acanthamoeba culbertsoni
3. Acanthamoeba hutchetti
4. Acathamoeba polyphaga
5. Acanthamoeba rhysoides
37
Acanthamoeba spp.:
type of organism
aquatic
38
Acanthamoeba spp.:
habitat
natural and artificial environments;
can survive even in contact lens solution
39
Acanthamoeba spp.:
entry
1. eyes
2. nasal passages to lower RT
3. ulcerated or broken skin
40
Acanthamoeba spp.:
Possible reservoir hosts for?
medically important bacteria
1. Legionella spp.
2. mycobacteria
3. gram-negative bacilli (E. coli)
41
Acanthamoeba spp.:
infective stage
both trophozoite and cyst
42
Acanthamoeba spp.:
Trophozoites reproduce by?
binary fission
43
Identify the parasite and diagnostic stage:
eats gram-negative bacteria, blue-green algae, or yeasts
Acanthamoeba spp. trophozoites
44
Identify the parasite and diagnostic stage:
can adapt to feed on corneal epithelial cells and neurologic tissue through phagocytosis and secretion of lytic enzymes
Acanthamoeba spp. trophozoites
45
Acanthamoeba spp.:
What happens when environmental conditions are unfavorable?
Trophozoites transform to cyst
46
Acanthamoeba spp. trophozoite:
nucleus:
karyosome:
cytoplasm:
nucleus: single large nucleus
karyosome: centrally located, densely staining
cytoplasm: finely granulated
47
Acanthamoeba spp. cyst:
nucleus:
karyosome:
nucleus: single large nucleus
karyosome: large karyosome
48
Acanthamoeba spp. trophozoite:
additional structures
1. acanthapodia: "thorn-like" appendages
2. contractile vacuoles
49
Acanthamoeba spp. cyst:
additional structures
double-walled cyst
1. outer wall: wrinkled
2. inner wall: polygonal
50
Acanthamoeba spp.:
disease manifestation and pathogenesis
1. Acanthamoeba Keratitis
2. Granulomatous Amebic Encepehalitis (GAE)
3. Cutaneous Lesions
51
Identify the disease:
parasite enters through eyes
Acanthamoeba Keratitis
52
Acanthamoeba Keratitis:
Acanthamoeba was first described in 1974 as an?
opportunistic ocular surface pathogen
53
Acanthamoeba spp.:
associated with use of improperly disinfected soft contact lenses
Acanthamoeba Keratitis
54
Acanthamoeba Keratitis:
symptoms
1. severe ocular pain
2. blurring vision
3. corneal ulceration with progressive corneal infiltration
55
Acanthamoeba Keratitis:
Primary amebic infection or secondary bacterial infection may lead to?
hypopyon formation
56
Acanthamoeba Keratitis:
may lead to?
1. scleritis
2. iritis
3. vision loss
57
Acanthamoeba Keratitis:
Can be mistaken for?
herpes keratitis;
(to differentiate, herpes has no ocular pain)
58
Stamm in 1972- documented Acanthamoeba as causative agent of human _______ using indirect fluorescence microscopy
GAE
59
Identify the disease:
Disseminated disease in lungs and brain
Granulomatous Amebic Encephalitis (GAE)
60
Granulomatous Amebic Encephalitis (GAE) usually occurs in?
immunocompromised hosts:
1. chronically ill and debilitated patients
2. those on immunosuppressive agents like chemotherapy and antirejection medications
61
AIDS patients have the highest risk of acquiring this
Granulomatous Amebic Encephalitis (GAE)
62
Granulomatous Amebic Encephalitis (GAE):
incubation period
10 days
63
T/F:
Granulomatous Amebic Encephalitis (GAE) is chronic, slow in progression (long-standing).
True
64
Granulomatous Amebic Encephalitis (GAE):
signs and symptoms
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
T/F:
GAE normally results in coma or death (has poor prognosis).
True
66
Identify the disease:
Presence of hard erythematous nodules or skin lesions
Cutaneous lesions
67
Common in AIDS patients
Cutaneous lesions
68
Cutaneous lesions:
parasite entry
through the skin
69
Granulomatous Amebic Encephalitis (GAE):
laboratory diagnosis
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
Acanthamoeba Keratitis:
laboratory diagnosis
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
Acanthamoeba spp. diseases:
culture
Culture: Cubertson’s Medium; Non-nutrient medium with Gram negative bacteria (usually Escherichia coli)
72
Acanthamoeba spp. diseases:
treatment
1. Fluorocystine
2. Ketoconazole
3. Amphotercin B
73
Balamuthia mandrillaris:
family
Leptomyxidae
74
Identify the parasite:
New species causing amebic meningoencephalitis
Balamuthia mandrillaris
75
Identify the parasite:
Also causes Granulomatous Amebic Encephalitis (GAE)
Balamuthia mandrillaris
76
Balamuthia mandrillaris:
Cysts have this characteristic
wavy appearance
77
Balamuthia mandrillaris:
Trophozoites are __________.
branching
78
Identify the parasite:
Almost the same appearance with Acanthamoeba
Balamuthia mandrillaris
79
T/F:
Balamuthia mandrillaris: Both cysts and trophozoites can be seen in the brain (when infected)
True
80
Other free-living ameba that causes amebic encephalitis
1. Sappinia diploidea
2. Hartmanella vermiformis
81
considered now as opportunistic
Hartmanella vermiformis
