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Amoebiasis and Giardiasis Flashcards

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1
Q

Entamoeba species

are taxonomically within the

subphylum ________

class ________

family _________

A

Sarcodina

Lobosea

Entamoebidae

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2
Q

Entamoeba histolytica is a/an (invasive or non-invasive?) enteric ________ parasite that is the cause of amoebiasis

A

invasive

protozoan

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3
Q

Entamoeba _______, Entamoeba _______, and Entamoeba ________ are parasites that are identical morphologically to E. _______,

A

dispar

moshkovskii

bangladeshi

histolytica

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4
Q

Entoameba species

E. dispar is (pathogenic or nonpathogenic?)

E. moshkovskii causes (invasive or noninvasive?) diarrhea

E. bangladeshi is of (known or unknown?) virulence.

A

nonpathogenic

noninvasive

unknown

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5
Q

Entoameba species

________,________, and _______ cannot be distinguished by stool _______ and _______ (O&P) test

A

E. histolytica, E. dispar, and E. moshkovskii

ova and parasite

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6
Q

Entamoeba spp.
At least seven additional species of amebae

(Entamoeba _______ , Entamoeba _______, Entamoeba _______, Entamoeba _______, _______ _______ , _______ _______, and _______ _______) infect the human intestine but are generally accepted as _______ organisms

A

Entamoeba coli
Entamoeba hartmanni
Entamoeba polecki
Entamoeba chattoni
Dientamoeba fragilis
Iodamoeba bütschlii
Endolimax nana

commensal

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7
Q

Entamoeba spp.

_______,______,_________ have occasionally been implicated as causes of diarrhea

A

E. polecki, Dientamoeba fragilis, and I. bütschlii

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8
Q

Amoebiasis is defined as _______ infection by _________ species, including E. histolytica, which is the cause of ________,_________, and rarely, ______

A

human

Entamoeba

amebic colitis, liver abscess

brain abscess

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9
Q

HISTORY 1875 LOSCH – RUSSIAN.

Differentiated the ______ dysentery from ________ dysentery by describing _______

1887 KARTULIS – EGYPT. Found _____________ from a liver abscess.

A

amoebic; bacillary; amoeba in the stool.

amoeba in the pus

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10
Q

HISTORY

1881 COUNCILMAN AND COFFLEUR. Described _________ and used the term _________

1903 SCHAUDINN. Differentiated __________ and _________ types of amoeba

A

true bowel lesions

Amoebic Dysentery.

pathogenic and non pathogenic

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11
Q

Epidemiology of amoebiasis

Worldwide: prevalence is about ___% to ____%

higher incidence of amoebiasis in
– developing countries.
– (male or female?) ——————, _______ and institutionalized populations.

A

10

50

Male ; homosexuals; travelers

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12
Q

Epidemiology of amoebiasis

Prevalence of amebic infection varies with level of ______ and generally higher in _______________ than in _______ climate

A

sanitation

tropics and subtropics

temperate

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13
Q

Epidemiology of amoebiasis

_____ passers are important source of infection

_______________ is the second leading cause of mortality due to parasitic disease in humans. (The first being _________).

A

Cyst

Entamoeba histolytica

malaria

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14
Q

Epidemiology of amoebiasis

____________ is the second leading cause of mortality due to parasitic disease in humans. (The first being ________).

Amebiasis is the cause of an estimated _____-________ deaths each year.

A

Entamoeba histolytica

malaria

50,000- 100,000

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15
Q

Transmission of amoebiasis

___________

sexual transmission among _____________ (_______-______)

Food or drink contaminated with _______ containing ___________

Use of human feces (night soil) for soil fertilizer by flies, and possibly cockroaches

A

Faeco-oral

homosexual males; oral- anal

feces containing the E.histolytica cyst

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16
Q

Pathogenic mechanisms of anoebiasis

receptor-mediated __________________ ( ______________ )

secreting _______ enzymes(________ ) and ________ substances.

contact-dependent _________/________ of target cell

____________ - amoebic ________ of killed target cell

A

adherence of amebae to target cell; adherence lectin

proteolytic; histolysine; cytotoxic

cell killing/amebic cytolysis

cytophagocytosis; phagocytosis

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17
Q

PATHOGENESIS of amoebiasis

The pathogenesis of amoebiasis centers on the unique ________ properties for which the organism was named histolytica.

Tissue invasion involves a ______-dependent process

Parasite binds to the _________ layer of host’s colonic epithelium by the parasite’s ____________, .

________ host’s immune mechanisms and destroys host’s cells

invade the intestinal epithelium and form ________ with a _________ center and ______ edges, from which ____,________, and ________ pass.

The ________ multiply and accumulate above the _________, often spreading _______.

Rapid lateral spread of the multiplying amebae follows, undermining the mucosa and producing the characteristic “___________ ” ulcer of primary amoebiasis

A

tissue-destructive

contact; mucin

Gal/GalNAc lectin; Overcomes

discrete ulcers; pinhead-sized ; raised

mucus, necrotic cells, and amebae

trophozoites; muscularis mucosae; laterally

flask-shaped

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18
Q

Pathogenesis of Amoebiasis

Trophozoites may penetrate the ______ layers and occasionally the ______, leading to perforation into the ___________

Subsequent _______ of the necrotic area produces gross changes in the ulcer, which may develop ____________________

Secondary bacterial invasion, and accumulation of neutrophilic leukocytes.

Lesions may extend to other parts of the GIT

An amebic ___________ or _________________________ mass (ameboma) may form on the intestinal wall and may lead to ________________

A

muscle; serosa; peritoneal cavity.

enlargement; shaggy overhanging edges

inflammatory or granulomatous tumor-like

intestinal obstruction

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19
Q

E. histolytica is found primarily in the _____ where it can live as a ______________ or invade the intestinal mucosa (green).

The ameba can metastasize to other organs via a _______ route (purple); primarily involving the _______ and ______.

The ameba can also spread via a _________ (blue) causing a ______ infection, ______ lesions or ______ ulcers.

A

colon

non- pathogenic commensal

hematogenous

portal vein and liver

direct expansion ; pulmonary; cutaneous; perianal

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20
Q

Factors that determine invasion of amoebae

the ________ of amebae ingested,

the _______________ of the parasite strain

host factors such as _________

______________ of the host, susceptibility of the host; ________ status

the presence of _______________ that enhance amebic growth

A

number

pathogenic capacity/ virulence

gut motility

immune competence

nutrition; suitable enteric bacteria

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21
Q

Morphology Different form of E. histolytica

_________

______ (________ nuclei)

A

trophozoite

cyst

1, 2, 4

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22
Q

Trophozoite of amoeba

•Size:12-60μm in diameter

•(Invasive or Non-invasive?) form ( minuta) / E. _____

•(Invasive or Non-invasive?) form (magna) contain _____, E. ________

A

Non-invasive; dispar

Invasive ; RBC; histolytica

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23
Q

Symptomatic infection

A
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24
Q

Symptomatic infection

Can either be A or B

A can be divided into C and D

B can be divided into E, F, G

A

A= Intestinal Amebiasis

B= Extraintestinal Amebiasis

C= Diarrhoea

D= Dysenteric colitis

E= hepatic

F=pulmonary

G=extra foci

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25
Q

Clinical manifestation of amoebaiasis

•Asymptomatic cystic passage/ carrier

Risk to _________ as a __________

Risk of __________ to the host

•Amoebic ______________

A

community; source of new infection

invasive disease

diarrhea

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26
Q

Clinical manifestation of amoebaiasis

Amoebic dysentry

= _________+_______+____________ in patient with E.histolytica infection

•(Gradual or Sudden?) onset of symptoms over ______

•Increasing ______ + abdominal ________

•_____ may be absent

A

Amoebic diarrhoea + mucus +visible or microscopic bloo

Gradual ; 3-4weeks

severe diarrhoea ; tenderness

Fever

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27
Q

Complications of Amoebiasis

List 5

A

Perforation
Ameboma intestinal obstruction
Necrotizing colitis
Toxic megacolon
Intussception

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28
Q

Extraintestinal infections(metastatic
amoebiasis)

metastatic is due to _______, rarely occurs by _________ from the bowel

most common form is ________,_________

others include: amoebic empyema, amoebic ________ abscess, amoebic _______ abscess.

A

micro emboli; direct extension

amoebic hepatitis or liver abscess

pericardial; cerebral

29
Q

Extraintestinal infections(metastatic
amoebiasis)

A true amebic abscess is ______,__________(unless secondarily infected), and _______ without __________ and ___________

The contents are _____ and bacteriologically _____, active amebae being ____________

A

progressive, nonsuppurative

destructive

compression and formation of a wall.

necrotic; sterile ; confined to the walls.

30
Q

Extraintestinal infections(metastatic
amoebiasis)

A characteristic “_________” is produced in the abscess and seen on surgical drainage

A

anchovy paste

31
Q

Amoebic liver abscess

10x more common in (men or women?) than (men or women?)

Symptoms: fever, cough, rt upper quadrant or epigastric pain

May be associated with GIT symptoms : nausea, vomiting, abdominal cramp , abdominal distention, diarrhoea, constipation

A

men than women

32
Q

Amoebic liver abscess

Lab findings:_________, abnormal ____________

Defect in hepatic imaging study

A

leukocytosis

liver enzymes

33
Q

Amoebic liver abscess

Amoeba is usually (present or absent?) from stool at the time of diagnosis

Differential diagnosis:
–__________
–_________

A

Absent

Hepatoma

Echinococcal cysts

34
Q

Diagnosis of amoebiasis

clinical Diagnosis:

Sigmoidoscopic examination:
presence of a _______ mucosa between the ____ serves to differentiate amebic from bacillary dysentery,( the _______________ in bacillary dysentery).

______megally

FBC. : leukocytosis in Amebic dysentery rises above 12000 per microliter, but counts may reach 16000 to 20000 per microliter.

A

grossly normal; ulcers

entire mucosa being involved

Hepato

35
Q

Diagnosis of amoebiasis
clinical Diagnosis:

Entamoeba histolytica must be differentiated from other intestinal protozoa including: ________,______,______

Differentiation is possible, but not always easy, based on morphologic characteristics of the cysts and trophozoites.

The nonpathogenic Entamoeba ______, however, is morphologically (identical to or different from?) E. histolytica, and differentiation must be based on isoenzymatic or immunologic analysis.
Molecular methods are also useful in distinguishing between E. histolytica and E. dispar and can also be used to identify E. polecki.

A

E. coli, E. hartmanni, E. dispar

dispar

identical to

36
Q

Microscopy (Stool Ova and Parasite Examination) of amoebiasis

Microscopic identification This can be accomplished using:

Fresh stool:_____ mounts, ______ mounts and ______________ preparations (e.g., _______).

Concentrates from fresh stool: wet mounts, with or without ____ stain, and permanently stained preparations (e.g., __________).

A

wet; iodine; permanently stained ; trichrome

iodine; trichrome

37
Q

In the absence of ____________, the pathogenic E. histolytica is morphologically indistinguishable from the nonpathogenic E. dispar!

A

erythrophagocytosis

38
Q

____________________ is the only morphologic characteristic that can be used to differentiate E. histolytica from the nonpathogenic E. dispar.

A

Erythrophagocytosis

39
Q

Antigen Detection in amoebiasis

Antigen detection may be useful as ______ to ________ diagnosis in detecting parasites and to distinguish between pathogenic and nonpathogenic infections.

A

An adjunct

microscopic

40
Q

Culture of E. histolytica from stool samples is available in ————- research laboratories worldwide

Culture is, in general, (more or less?) sensitive than stool O&P examination but significantly (more or less?) sensitive than culture and serology

A

only a few

More

Less

41
Q

Molecular diagnosis

______ is the method of choice for discriminating between the pathogenic species (E. histolytica) from the (nonpathogenic species (E. dispar.

A

PCR

42
Q

Prevention and control of amoebiasis

Prevention of ___________ of food and water

use of __________ in men who have sex with men

proper maintenance of municipal water supplies to prevent access of ——————— to the treated water supply.

A

fecal contamination

safe sexual practices

chlorine resistant amebic cysts

43
Q

Serology

serology
Antibody detection or Antigen detection
The indirect hemagglutination (IHA) Rapid latex agglutination tests Immunobloting

The EIA test detects antibody specific for E. histolytica in approximately 95% of patients with _________ amebiasis, 70% of patients with __________ infection, and 10% of _______ persons who are _______________________

A

extraintestinal

active intestinal

asymptomatic

passing cysts of E. histolytica

44
Q

Difference between E. histolytica and E.coli

Xterics : Histolytica: Coli

Size of cysts
Nuclei
Size of trophozoites
Erythrophagia
Intracellular karyosomes
Ring of nuclear chromatin
Cytoplasm
Movement

A

12-14um; 10-35um

4;8

10-10um; 10-50um

Present ; absent

Tiny and centrally placed; Large and eccentric

Evenly dispersed, beadlike; Blotchy distribution

Smooth, finely granular; Rough

Unidirectional motility extends pseudopods only in one plane; Moves in different directions. extends pseudopods multiple planes

45
Q

Giardia lamblia also known as G._______ or G. _______

A _________ pathogenic protozoan found in the _______ and _______ of humans

A

intestinalis; duodenalis

flagellated

duodenum and jejunum

46
Q

Giardia lamblia

a common cause of ____,______,_______, and ______ diarrhea throughout the world

A

sporadic, endemic, and epidemic

47
Q

Giardia lamblia

1600s- van Leeuwenhoek discovered it in ____________.

in the early ______ that the parasite received the genus name Giardia.

A

his own stool

1900s

48
Q

Giardiasis

Prevalence -______% in industrialized countries

________% in developing countries

• Caused by Giardia ________/ Giardia _____

A

2-5

20-30

intestinalis

lamblia

49
Q

Giardiasis

•______ is the main reservoir
• Inhabit ___________________________

A

Man

duodenum, jejunum & upper ileum

50
Q

Giardia is one of the most widely distributed enteric parasites.
T/F

A

T

51
Q

Giardia

it is most frequently reported in children aged ______ years and adults aged ________ years.

In low-income countries, Giardia infects nearly ____ children by the age of ____ years.

A

1 to 9; 35 to 45

all; 10

52
Q

Giardia

Commoner among ________ children

Transmission of this ______ parasite is most common through person to person

A

malnourished

fecal-oral

53
Q

Transmission of Giardia

Infective form –_______ passed in feces of man

• Routes of transmission –______, ______________ – most important
Ingestion of contaminated food
Person to person – day care, nursing homes, mental asylums (poor hygiene and formites)

– Sexual – ——————————

A

mature cyst

Feco-oral

ingestion of contaminated water

sexually active homosexual males

54
Q

Giardia

Life cycle

composed of two stages:
the _________, or freely living stage
the ______.

A

trophozoite

cyst

55
Q

Morphology of Giardia lamblia
trophozoite

______ shaped, _____ anterior end, posterior end ______ (looks like _______ face)

A

Pear; rounded; pointed; monkey

56
Q

Morphology of Giardia lamblia
trophozoite

Size: 12 to 15 μm long x 5 to 9 μm wide
Dorsal surface _____, ventral surface _______

Ventral surface bears ________ to adhere to surface of ___________

A

convex; concave

sucking disk; intestinal cell

57
Q

Morphology of Giardia lamblia
trophozoite

Bilaterally symetrical: 2 ______, 2 _______, 4 _____________ (2 anterior, 2 posterior, 2 ventral, and 2 caudal) actively motile and feeding stage

Habitat: _____________

May invade the __________

A

nuclei; axostyles

pairs of flagella

small intestine

common bile duct.

58
Q

Trophozoite of Giardia

Size is a ______-shaped organism

has _____ pairs of flagella

approximately 15 μm in length (:9 to 21 μm long and 5 to 15 μm wide).

A

heart; four

59
Q

Trophozoite of Giardia

A (small or large?) (concave or convex?) ________ on the (ventral or dorsal?) surface helps the organism to adhere to intestinal villi

A

Large ; concave; sucking disk

Ventral

60
Q

Trophozoites of Giardia

As the parasites pass into the colon, they typically _______, and the ______ are passed in the stool.

They are _______, (thin or thick?) -walled, (mild or highly?) resistant, and 8–14 μm in length

they contain _____ nuclei as immature forms and _____ as mature cysts.

A

encyst; cysts

ellipsoid; thick; highly

two; four

61
Q

Life cycle of Giardia

Infection acquired by – ingestion of _______

___________ occurs in stomach & duodenum within __________

_____________ hatch from one cyst

Trophozoites multiply by ___________ & colonize in duodenum & upper jejunum

Trophozoites adhere to ______ by _________

_________ occurs in transit down the colon

Axonemes retract, cytoplasm condense & thin tough hyaline wall is secreted

__________ undergo nuclear division –mature ________nucleate cyst

A

mature cysts

Excystation ; 30 minutes

2 trophozoites; binary fission

enterocytes; ventral suckers

Encystation

Encysted trophozoite; quadrinucleate

62
Q

Life cycle of Giardia

Infection occurs by _________ of as few as ____________

incubation period- __________

After _________, trophozoites colonize and multiply in the upper small bowel.

Adherence in the human gut is most likely via the ______, with attachment at the brush border of enterocytes by either a _______ or a _______ mechanism.

A

ingestion; 10-25 cysts

1 to 2 weeks

excystation; ventral disk

suction or a clasping

63
Q

Pathogenesis of Giardiasis

pathogenic mechanisms include:
– disruption of the ______________________,
_______ invasion

-elaboration of an _______
– Disruption of __________
– increase _________
-induction of ___________

A

intestinal epithelial brush border and function

mucosal; enterotoxin

tight junctions; permeability

apoptosis

64
Q

Pathology of Giardiasis

Do not __________
Feed on _________
May localize in ______ to avoid the acidity of duodenum
Cause ______ of duodenum & jejunum

Cause ________ as the parasite coats the mucosa & damage epithelial brush border
Stool contains large amounts of ______ and _______ but no _______

A

invade tissues; mucous secretions

biliary tract ; inflammation

malabsorption

mucous & fat but no blood

65
Q

Giardiasis

Initially, stools may be _______ and _______, but later they are commonly ——-,————-, and _________

Patients who develop chronic diarrhea have profound malaise, lassitude, occasional headache, and diffuse abdominal and epigastric discomfort often exacerbated by _______.

Stools may be ______ and _____ or _____,_______, occurring in small volume, and frequently passed.

Weight loss is usually (present or absent?)

A

profuse and watery

greasy, foul smelling, and may float

eating

greasy and foul smelling ; frothy, yellowish

present

66
Q

Clinical features of giardiasis

Asymptomatic : largest group,_______

Acute :_______ infection, acute _____ diarrhoea, abdominal _____, bloating, _________. Stool is _____ and ______ in earlier disease. ____,_______, and ______(____) later

Chronic : chronic diarrhoea with ________ syndrome, __________

A

cyst passage

self-limiting; watery; cramps; flatulence

profuse & watery

Voluminous foul smelling & greasy (steatorrhoea)

malabsorption; steatorrhoea

67
Q

Complication of Giardiasis

________________ syndrome
Failure to ______
Post-Giardia ___________
Chronic ______ syndrome
Post-Giardia ____________
Extraintestinal manifestations : urticaria, other skin rashes, reactive arthritis, eye complaints, biliary tract disease, and gastric infection

Gastric infection occurs exclusively in the presence of _________

A

Malabsorption; thrive

irritable bowel syndrome

fatigue; lactose intolerance

achlorhydria

68
Q

Treatment of Giardiasis

_______ is the drug of choice, taken in a single dose

Alternatives are – ______,_______,______

A

Tinidazole

Metronidazole

Nitazoxanide

albendazole.

69
Q

chlorination of water affects the cysts

T/F

A

F

chlorination of water does not effect the cysts

House Microbiology (93 decks)

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