Module 3 Flashcards
(121 cards)
1
Q
What amoebae has a worldwide prevalence, especially where sanitation is poor and is more common in developing countries of the tropics where Majority of cases are asymptomatic
A
Entamoeba Histolytica
2
Q
What amoeba is found in the human colon
A
Entamoeba Histolytica
3
Q
What is the morphology of Entamoeba Histolytica? (occurs in 3 forms)
A
- Trophozoite
- Precyst
- Cyst
4
Q
the vegetative form of the parasite and the only form present in tissues
A
Trophozoite form of Entamoeba histolytica
5
Q
what size does the trophozoite form of Entamoeba histolytica vary from and what is the average size?
A
varies in size from 12 to 60 μm, average being 20 μm
6
Q
What two components does the cytoplasm of Entamoeba histolytica consist of ?
A
ectoplasm and endoplasm
7
Q
is clear and transparent
A
ectoplasm
7
Q
is finely granular and contains nucleus, food vacuoles and phagocytosed erythrocytes
A
Endoplasm
8
Q
what are the three components of endoplasm
A
nucleus, food vacuoles and phagocytosed erythrocytes
9
Q
finger-like projections formed by movements of ectoplasm in one direction
A
Pseudopodia
10
Q
spherical and contains central karyosome
A
nucleus
11
Q
The nuclear membrane is lined by a rim of evenly distributed
A
chromatin
12
Q
Trophozoite form of Entamoeba histolytica reproduces by what process?
A
binary fission
13
Q
What are the three ways to kill the trophozoite form of Entamoeba histolytica?
A
drying, heat and chemical sterilization
14
Q
where does the trophozoite of Entamoeba histolytica undergo encystment
A
in the intestinal lumen
15
Q
what size is the precystic stage of the trophozoite of Entamoeba histolytica
A
10–20 μm in size
16
Q
Immature cyst contains a
A
single nucleus, a glycogen vacuole and chromatoid bars
17
Q
what are the shapes of chromatoid bars
A
cigar shaped with rounded ends
18
Q
chromatoid bars are visible in what
A
saline
19
Q
nuclear chromatin and chromatoid bodies appear deep blue or black in what stain
A
hematoxylin stain
20
Q
When stained with iodine, the glycogen mass appears what color
A
golden brown
21
Q
When stained with iodine the nuclear chromatin and
karyosome appear what color
A
bright yellow
22
Q
How many nuclei does a mature Entamoeba histolytica cyst contain
A
4 nuclei
23
Q
what components disappear in the mature cyst of Entamoeba histolytica
A
glycogen mass and chromatoid bars
24
what two things is the cyst wall highly resistant to
gastric juice and unfavorable environmental conditions
25
where are the cysts of Entamoeba histolytica usually found?
formed stools
26
where are the trophozoites of Entamoeba histolytica usually found?
loose stools
27
Cysts are ingested via
contaminated food and water
28
where do the cysts undergo excystation
in the intestine
29
260 kDa galactose and N-acetylgalactosamine inhabitable surface protein (Gal/NAG lectin)
Amoebic lectin antigen
30
what are the two subunits of amoebic lectin antigen
heavy (170 kDa) and light (35 kDa)
31
What links the heavy and light units of GalNAGlectin
disulfide bridge
32
what is the principle virulence factor in Entamoeba histolytica
lectin antigen
33
Lectin antigen is present on the surface of trophozoites of pathogenic E. histolytica but not on nonpathogenic E. dispar. True or False?
True
34
What are the pathogenic mechanisms of lectin anitgen?
Adhesion, Cytotoxicity, Complement Resistance
35
Inserts ion channels in the target cell membrane causing leakage of ions
Amoebapore
36
What is the equivalent of Amoebapre in E. dispar
dispar pores
37
They degrade extracellular matrix, responsible for invasion, secreted only by trophozoites of pathogenic E. histolytica
Cysteine proteases
38
Give 3 examples of cysteine proteases
histolysin, amoebapain and cathepsin B
39
help in the destruction of the target tissue
hydrolytic enzymes
40
Give 3 examples of hydrolytic enzymes
RNAse, neutral protease and phosphatases
41
Name the two virulence factors that help in invasion
Neuraminidase and metallocollagenase
42
What two components are in the 170 kDa subunit
cytoplasmic and toxic membrane domain
43
This pathogenic mechanism binds to glycoprotein receptors on intestinal and hepatic surfaces in amoebic lectin antigen
adhesion
44
This pathogenic mechanism by contact dependent cytolysis of the target cells by increasing the calcium level
Cytotoxicity
45
The 170kDa subunit resembles CD59 that prevent C5b-9 complex formation. What pathogenic mechanism is this?
Complement resistance
46
what human component blocker does 170kDa subunit resemble
CD59
47
True or false? Entamoeba histolytica causes intestinal and extraintestinal amoebiasis
True
48
True or False? The lumen-dwelling amoebae do not cause any illness
True
49
True or False? trophozoites do not cause disease when they invade the intestinal tissues
False, They cause disease only when trophozoites invade the intestinal tissues
50
a tissue lytic enzyme, which damages the mucosal epithelium
histolysin
51
True or False? Amoebic lectin does not mediate adherence
False, Amoebic lectin mediates adherence
52
True or False? Mucosal penetration does not produce discrete ulcers with pinhead center and raised edges
False, it does produce discrete ulcers with pinhead center and raised edges
53
True or false? In Entamoeba histolytica sometimes, the invasion remains superficial and heals spontaneously
True
54
True or false? ulcers are multiple and are confined to the colon, being most numerous in the caecum and
recto-sigmoidal region
True
55
True or false? In Entamoeba histolytica the intervening mucous membrane between the ulcers remains healthy
True
56
True or false? amoebic ulcer is flask shaped in cross-section
True
57
True or False? Multiple ulcers may coalesce to form large necrotic lesions with ragged and undermined edges and are covered with brownish slough
True
58
True or False? ulcers generally extend deeper than submucosal layer
False, ulcers generally do not extend deeper than submucosal layer
59
What are the clinical manifestations of Entamoeba Histolytica
Diarrhea, vague abdominal symptoms and dysentery
60
How can E. Histolytica survive harsh/acidic environments
it has a chitinous cyst wall
61
What does ALA stands for?
Amoebic Liver Abscess
62
True or false? In ALA acidic phosphatase is a common finding
False, Alkaline phosphatase
63
What two things can cause excystation
gastric acid and digestive enzymes
64
True or False? Amoebae are seen at the periphery of the lesions and extending into the surrounding healthy tissues
True
65
True or False? The clinical manifestations of Entamoeba Histolytica may resemble dysentery
True
66
The ulcers may involve the muscular and serous coats of the colon causing what two symptoms?
perforation and peritonitis
67
True or false? Blood vessel erosion may cause hemorrhage
True
68
What may develop on the intestinal wall from a chronic ulcer?
Granulomatous pseudotumoral growth
69
True or false? It is easy to differentiate an amoebic granuloma/ amoeboma from a malignant tumor.
False, amoebic granuloma or amoeboma may be mistaken for a malignant tumor
70
How long is the incubation period for intestinal amoebiasis?
1 to 4 months
71
What percentage of patients with intestinal amoebiasis will develop amoebic liver abscess (ALA)
5-10%
72
True or False? ALA arises from hematogenous spread of amoebic trophozoites from colonic mucosa or by direct extension
True
73
True or False? Often, ALA patients have bowel symptoms
False, Often ALA patients do not present with bowel symptoms
74
True or false? Liver damage may not be directly caused by the amoebae, but by lysosomal enzymes and cytokines from the inflammatory cells surrounding the trophozoites
True
75
The center of the abscess contains thick brown pus (anchovy sauce). What is the thick brown pus consist of?
liquified necrotic liver tissue of amoeba
76
W
77
True or false? Liver abscess may be multiple or more often solitary, usually located in the upper right lobe of the liver
True
78
True or false? Jaundice develops only when lesions are multiple or when they press on the biliary tract
True
79
True or false? Large, untreated abscess may rupture into the lungs and pericardium
True
80
True or False? The incidence of liver abscess is more common in adult males
True
81
What are the other complications of intestinal amoebiasis?
❖ Amoebic cerebral abscess
❖ Amoebic peritonitis
❖ Genitourinary amoebiasis
❖ Perianal ulceration
❖ Pulmonary amoebiasis
❖ Splenic abscess
❖ Toxic megacolon
82
True or false? Infection with invasive strains will activate both humoral and cellular immune responses
True
83
What is the specimen of choice for laboratory diagnosis of intestinal amoebiasis?
Stool
84
What can be used to preserve stool specimen for Intestinal amoebiasis
polyvinyl alcohol or merthiolate iodine or formalin
85
This culture media contains bacterial supplement, starch and serum providing nourishment to amoeba.
Polyxenic culture
86
What are the various culture media used for polyxenic culture?
a) National Institute of Health (NIH) media
b) Boeck and Drbohlav egg serum medium containing Locke’s solution
c) Balamuth’s medium
d) Nelson’s medium
e) Robinson’s medium
87
This culture lacks bacterial supplement, e.g., diamond’s medium.
Axenic culture
88
What are the various tests used to demonstrate amoebic coproantigen in stool
a) Counter current immune electrophoresis (CIEP)
b) Enzyme linked immunosorbent assay (ELISA)
c) Immunochromatographic test (ICT)
d) ELISA detecting 170 kDa of lectin antigen
e) Immunochromatographic test
89
is found only in patients with active
infection and disappears after clinical cure, so its presence in serum indicates recent
and active infection
amoebic antigen
90
is done using monoclonal antibody specific for lectin antigen—usually positive in early stage of the disease
ELISA
91
also available using monoclonal antibody specific for various other antigens like—serine rich E. histolytica protein (SREHP), lysine rich surface
antigen and lipophosphoglycan (LPG)
ELISA
92
What are the 3 older methods for antigen detection
1) CIEP
2) Coagglutination test
3) Slide agglutination test
93
List several isoenzymes in E. histolytica
malic enzyme, hexokinase, isomerase, and
phosphoglucomutase
94
It can also be used to differentiate E. histolytica and E. dispa
Isoenzyme (zymodeme) analysis
95
isoenzymes are subjected to electrophoresis, based on the electrophoretic pattern and mobility of the isoenzymes, Entamoeba can be speciated
Isoenzyme (zymodeme) analysis
96
True or False? Realtime PCR can be used as alternate to the conventional PCR
True
97
With what sensitivity can Microscopy of liver pus detect trophozoites
less than 25%
98
True or false? Stool microscopy is useful when diagnosing amoebic liver abscess
False, Stool microscopy is not useful when diagnosing amoebic liver abscess
99
Name the various antibody detection methods
IHA, IFA, ELISA, CIEP, complement fixation test (CFT),
staphylococcal adherence test (SAT) and carbon immune assay (CIA)
100
In ___ organism appears bright pink with green blue back ground
PAS stain
101
What treatment matches the following? Diloxanide furoate, iodoquinol, paromomycin and tetracycline act in the intestinal lumen but not in tissues
Luminal amoebicids
102
What treatment matches the following? Emetine and chloroquine are effective in systemic infection, but less effective in the intestine
Tissue amoebicides
103
What is used for both luminal and tissue amoebicides?
Metronidazole (750–800 mg 3 times daily for 5–10 days), tinidazole and ornidazole act on both sites
104
Carriers should also be treated because of the risk of transmitting the infection to others. What should be used in these cases?
Paromomycin or iodoquinol
105
What are the methods of prevention and control for amoebiasis?
1. Boil drinking water
2. Wash fruits and vegetables in clean water before eating
3. Detection and treatment of carriers and prohibit them from food handling
4. Health education
106
What is another name for Nonpathogenic intestinal amoeba
commensal amoeba
107
is morphologically indistinguishable (both cyst and trophozoite) from E. histolytica, so it may be considered as a subspecies of E. histolytica.
Entamoeba dispar
108
This species was first described from Moscow sewage by Tshalaia in 1941 and was thereafter reported to occur in many different countries including
India
Entamoeba moshkovskii
109
It can be distinguished from E. histolytica by isoenzyme analysis, molecular methods and detection of lectin antigen
Entamoeba moshkovskii
110
It is nonpathogenic, usually colonizes in the large intestine (10 times more than E. histolytica) but doesn’t invade intestinal mucosa
Entamoeba dispar
111
▪ a nonpathogenic amoeba that colonizes the large intestine.
▪ The life cycle is similar to E. histolytica
▪ It has also three forms—trophozoites, precyst and cyst
▪ It is frequently found in the stool samples of healthy individuals and should be differentiated from that of E. histolytica
Entamoeba coli
112
It is also known as small race variant of E. histolytica, i.e. morphologically it is similar to E. histolytica but of smaller size (trophozoite is 8–10 µm and cyst is 6–8 µm
Entamoeba hartmanni
113
It is the first parasitic amoeba of humans to be described; recovered from the soft tarter
between the teeth
Entamoeba gingivalis
114
▪ It is a nonpathogenic amoeba usually found in the intestine of pigs and monkeys.
▪ However, human infection is rare, mainly restricted to Papua New Guinea where it is the most
common intestinal amoeba in humans
Entamoeba polecki
115
▪ found in apes and monkeys and is morphologically identical to E.
polecki.
▪ More recently, it has been detected in eight human infections.
Entamoeba chattoni
116
Identification of E. chattoni was done via
isoenzyme analysis.
117
Direct examination of stool by saline and iodine mount if done to demonstrate:
trophozoites
qudrinucleated cysts
118
saline mount is used for?
trophozoites
119
iodine mount is used for?
demonstrates the internal structures of cysts
120
it shows the side of the abscess and its extension in the liver
ultrasonography
