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Micro > Diarrheagenic Protozoan > Flashcards

Diarrheagenic Protozoan Flashcards

1
Q

Acquiring Giardiasis

A

zoonosis - beaver, dogs, cats, and primates

drinking contaminated drinking water

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2
Q

At risk for giardia

A 
children
immoncompromised
day care workers
backpackers/campers
drink shallow well water
oral sex
travel
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3
Q

What causes giardiasis

A

G. Lamblia (G. intestinalis)

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4
Q

Most commonly identified intestinal parasite in the world

A

G. lamblia

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5
Q

G. lamblia description

A

flagellate protozoan; no intermediate hosts required

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6
Q

Morph stages of g. lamblia

A

Trophozoite, cyst (infective)

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7
Q

Trophozoite of g. lamblia

A

exists freely in small intestine; TEAR DROP W/ BILOBED VENTRAL DISCS, FLAGELLA AND 2 NUCLEI; does not invade tissue/RBC; feeds on mucous

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8
Q

Cyst of g. lamblia

A

form passed into environment;
oval, hyaline wall
4 nuclei when mature
1 cyst = 2 trophozoites

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9
Q

Giardia life cycle:

A

ingest cyst –> encystation in stomach (acid/enzymes) –> trophozoites (pathogenic) pass into small bowel where they divide quickly (9-12 hrs) –> trophozoites in large bowel encyst in neutral pH and bile –> cyst passed to environment

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10
Q

Epidemiology of Giardiasis

A

highly contagious
drinking water contaminated w/ feces
Children/developing countries (June-Oct)
Rocky Mountains

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11
Q

Infective dose of g. lmablia

A

10-25 cysts (>25% = 100% infection rate); 2 week incubation; can be STI

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12
Q

Sx of giardia

A 
Watery Diarrhea (NO BLOOD)
Stomach pain/anorexia
B12 Deficiency (malabsorption)
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13
Q

Virulence of G. lamblia

A

ventral disc imprints on intestinal mucosa – damages mucosa by flattening vili (leads to malabsorption)

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14
Q

Dx of g. lamblia

A

O&P exam/stool sample

ELISA - detects GSA65 (problem: antibodies carried >2 years in humans)

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15
Q

Prognosis of G. lamblia

A 
excellent
most pt. asymptomatic and self-limiting
weight loss, growth retardation
re-infection are possible 
Mortality rare = dehydration
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16
Q

Protozoan illness that can result in colitis and liver abscess

A

Amoebiasis

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17
Q

Cause of amoebiasis

A

E. hysitolytica

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18
Q

Species of entamoeba

A

many are nonpathogenic; E. histolytica is only one that causes disease; E. dispar is commensal (HIV positive patients)

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19
Q

Causes wide spectrum of illness

A

E. histolytica (intestinal and extraintestinal)

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20
Q

Morph of E. histolytica

A

Trophozoite (invasive, pathogenic), cyst (infective)

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21
Q

Trophozoite of E. histlytica

A 
1 nucleus
non-flagellated
feeds (invades tissue/RBC)
pseudopod-forming
invasive and pathogenic
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22
Q

Cyst of E. histolytica

A

round/oval; 4 nuclei

infectious stage

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23
Q

Life cycle of E.histolytica

A

ingest cyst –> excystation in colon –> forms highly motil trophozoites –> colonizes the mucosa of the colon (encyst and pass in feces OR invade intestinal mucosal barrier and go into bloodstream (dissemination))

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24
Q

Dissemination

A

E. histolytica invading and going into bloodstream

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25
Q

Epidemiology of Amoebiasis

A

most prevalent in tropical/subtropical
fecal contamination of watter and food
causes more deaths that any parasite other than malaria and shistosomiasis
reportable disease

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26
Q

High risk for amoebiasis

A 
children
pregnant
long term steroids
malnourished
immoncompromised
institutionalized
oral-anal sex
27
Q

Incubation period of amoebiasis

A

SHORT- 10 days (compared to 2 weeks for giardia)

28
Q

S/sx of Amoebiasis

A 
BLOODY STOOLS
fever, vomiting, weight loss
Extraintestinal- ulcers (RUQ pain)
Death from peritonitis, cardiac failure and exhaution
anemia (destroys RBC)
29
Q

Virulence factors of amoebiasis

A

“lets form a PAC…LPAC)
lectin - assist w/ adhesion
phospholipases
amoebapore- active peptide released to insert ion channel into host cell lipid struction (lysis host cell)
cystein proteases (degrade mucus/immunity, antibody, complements, cellular matrix)

30
Q

Dx of amoebiasis

A

trophozoites or cysts in stool
radiology (extraintestinal)- CT/MRI
ELISA- differentiates E. histolytica from E. dispar
PCR

31
Q

Tx of amoebiasis

A

metro/tinidazole + iodoquinol

may need surgical repair of abscesses

32
Q

Non medical tx of amoebiasis

A

purified water (cysts resistant to Chlorine!!!!) - boiling, iodine, bottled

33
Q

Resistant to chlorine

A

amoebiasis

34
Q

non-bloody, watery stools

A

Giardia

35
Q

Cryptosporidiosis cause

A

at least 15 species (hominis and parvum)
hominis- humans only
parvum- bovine and humans

36
Q

Prognosis of cyrpto

A

self-limiting in healthy

serious in immunocompromised (aids)

37
Q

Morph of Cryptosporidium

A

oocysts & sporozoites

38
Q

Oocysts of crypto

A

contain 4 sporozoites; infectious stage; does not multiply outside of host; asexual and sexual reproduction in host (sexual = evolution)

39
Q

Sporozoites

A

motile

bind receptors on surface of intestinal epithelial cells

40
Q

life cycle of crypto

A

ingest oocytes –> activated to release 4 infective sporozoites –> bind receptors on intestinal epithelial cells –> ingested into parasitophorous vacuole –> inside epithelial cell, parasite undergoes sexual/asexual reproduction to form more oocysts (thin/thick walled oocysts) –> oocyst shedding

41
Q

Thin walled oocysts

A

asexual; lead to reinfection of host

42
Q

Thick walled oocysts

A

sexual; shed into environment

43
Q

auto-infection possible

A

crypto (thin-walled)

44
Q

Parasitophorous vacuole

A

produced by crypto; near surface of epithelial cell, separated from cytoplasm by dense layer; protects crypto

45
Q

2 nuclei, flagella

A

giardia

46
Q

parasitophorous vacuole

A

crypto

47
Q

1 nuclei, no flagella

A

amoebiasis

48
Q

Epidemiology of crypto

A

fecal-oral contamination
sporadic cases from contaminated water/food – cows, recreational water (prevalent in swimmers/pools)
Associated with AIDS
developing countries

49
Q

People most likely to get crypto

A

AIDS, swimmers, work w/ cows

50
Q

Pathophys of crypto

A

highly infectious (10 oocysts; infective immediatly after excretion)
5-10 incubation
infection difficult to treat (vacuoles)
Infection: due to increased intestinal permeability, chloride secretion and malabsorption

51
Q

Sx of crypto

A

WATERY DIARRHEA
patient severely wasted
lasts ~2 weeks (self-limiting in immunocompetant)
Immunocompromised: bad prognosis if CD4 low, pancreatitis, severe weight loss

52
Q

Dx of crypto

A

oocysts in stool (zinc sulfate centrifugal flotation), IMMUNOFLUORESCENCE, acid fast oocysts are round, ELISA

53
Q

small, oval and acid fast

A

Crypto

54
Q

Linked to patients in latin america

A

cyclosporiasis

55
Q

Cause of cyclosporiasis

A

cyclospora cayetanensis

56
Q

Autofluorescent oocyst

A

Cyclosporiasis (much larger oocysts than crypto)

57
Q

how do you get cyclospora?

A

ingest oocyst in contaminated water and imported foods (fresh fruit and veggies)

58
Q

Life cycle of cyclospora

A

ingest oocyst –> similar progression;
resistant to chlorine
Oocysts shed in feces: MUST SPORULATE IN THE ENVIRONMENT (days– reinfection rare)

59
Q

Resistant to chlorine

A

Cryptosporidium, cyclospora

60
Q

Presentation of cyclospora

A

EXPLOSIVE, non-blood watery diarrhea

61
Q

Dx of cyclospora

A

Large oocyst in stool samle (difficult due to low #’s in stool, may have to repeat several days); ACID FAST POSITIVE, AUTOFLOURESCENT OOCYTE;
PCR

62
Q

Blastocystis hominis

A

polymorphic; ingest cyst from contaminated food/water (animal feces); LARGE CENTRAL VACUOLE, MULTIPLE NUECLEI AROUND RIM

63
Q

Balantidium Coli

A

large intestine microbe (zoonotic: pigs);
can result in GUT PERFORATION
Tropho and cyst forms: contains MACRONUCLEUS;
cilia evident on trophozoite

Micro (3 decks)

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