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Microbiology > intestinal protists > Flashcards

intestinal protists Flashcards

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1
Q

disease causing protists are associated with

A

all supergroups

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2
Q

what is one of the leading causes of death among children under five globally

A

diarrhoea

-1.5 mill a year

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3
Q

types of diarrhoea

A

osmotic
inflammatory
secretory

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4
Q

osmotic

A

enterocyte malfunction, impaired absorption, enhanced secretion, excessive solutes

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5
Q

inflammatory

A

mucosal invasion and leukocytes in stool

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6
Q

secretory

A

toxin associated and excessively watery

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7
Q

why do low income countries have more cases of diarrhoea

A

vaccine preventable, furthermore the rotaviruses which cause diarrhoea leave the body in stool. if you accidentally get the stool in our mouth, you get infected

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8
Q

rotaviruses

A

e.coli, shigella, campylobacter, salmonella, vibrio cholera

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9
Q

three solutions for diarrhoea

A
  • oral rehydration therapy
  • vaccines
  • safe drinking water
  • improved hygiene
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10
Q

how does oral rehydration therapy work

A

zinc deficiency reduces the number of B and T cells through the increased risk of apoptosis and reduces their functional capacity. the element stabilises the cell membrane, and since deficiceny disrupt the intestinal mucosa, reducing burst border enzymes and increasing mucosal permeability and intestinal secretion of water.
-zinc also acts as a potassium channel blocker, inhibiting cyclic adenosine monophosphate- mediated chlorine

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11
Q

since deficiency reduces..

A

the number of B and T cells through the increased risk of apoptosis and reduces their functional capacity

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12
Q

intestinal protists

A

o Entamoeba histolytica (Amoebozoa).
o Giardia intestinalis (Excavata).
o Dientamoeba fragilis (Excavata).
o Cryptosporidium hominis, C. parvum (Chromalveolate -apicomplexan).
o Balantidium coli (Chromalveolate - ciliate).
o Blastocystis sp (Chromalveolate - stramenopile).

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13
Q

fecal-oral transmission

A
  • protists ted to have similar transmission cycles
  • trophozoites inhabit intestinal tract but are not infectious
  • cysts are excreted and are infectious
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14
Q

intestinal structure

A
  • large surface area
  • 4 layers
  • microvilli
  • many blood and lymph vessels
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15
Q

parasite damage

A
  • water absorption impaired due to epithelial damage
  • crypt cells produce cells but excrete water and cl-
  • water not reabsorbed with Na+
  • villus blunting
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16
Q

gastroenteritis

A

gastrointestinal tract infections: nausea, vomiting, diarrhoea, abdominal distress

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17
Q

general disease of s.intestine indicates

A

excessive secretion relative to absorption

-fluid and electrolyte loss

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18
Q

dysentry

A

l. intestine

- involves blood and mucus in stool

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19
Q

which type of entamoeba cause disease in humans

A

E.Histolytica- amoebic dysentery

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20
Q

E.dispar vs E.histolytica

A
  • morpholigically indistinguishable

- 10-50% of work infected by E.dispar

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21
Q

drug used to treat histolytica

A

nitroimidazole

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22
Q

E. histolytica

A

typical decal oral life cycle- infectious cysts passed through faeces. Trophozoites replicated in large intestine.

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23
Q

how does E.histolytica cause damage

A

lyses cells in a constant dependent manner. It eats its way through the epithelium and beyond.

24
Q

breakdown of E.histolytica action

A

1) crawling and feeding
2) erosion of mucous layer for contact dependent killing
3) ECM breakdown and neutrophil killing
4) perforation of serous layers leading to peritonitis
5) access to circulatory system

25
Q

Giardia

A
  • most common parasite from human stool
  • results in asymptomatic infection
  • typical decal oral route
26
Q

where does giardia intestinalis colonise

A

upper portion of s.intestine.

27
Q

who first described giardia

A

Leeuwenhoek who found it in his own stool

28
Q

guardia parasite very rarely

A

penetrates the cells wall unlike Amebiasis

29
Q

what is used to diagnose giardia

A

the enterotest

30
Q

common symptoms of giardia

A

diarrhoea, malaise, flatulence, bloating, nausea, anorexia, weight loss

31
Q

pathogenesis of giardia

A
  • attachment could cause irritation and mucosal injury
  • bollus blunting and enterocyte apoptosis
  • uncreased crypt cell activity: hyperplasia
  • hypersecretion of cl- and water
32
Q

the adhesive disk of Giardia is

A

important for adhesion to intestinal epithelium

  • made from cytoskeleton and contractile proteins
  • inhibitors of microfilament also inhibits attachment
33
Q

treatment of Giardia

A

metronidazole cures around 85%

34
Q

what is the only know human infectious ciliate

A

Balantidium coli

35
Q

what disease does Balantidium coli cause

A

balantidiasis

36
Q

who are most at risk of getting balantidiasis

A

those who work with pigs, however less than <1%

37
Q

balantidiasis

A

fecal-oral transmission

-only known mammalian pathogen within the stramenopiles

38
Q

Balatidium coli

A
  • typical ciliate with cilia and micro and micronucleus
  • nuclear dimorphism
  • asymmetric division
  • diarrhea or dysentery
39
Q

Balatidium and diarhhea

A

rarely invades intestinal epithelium but then shows diarrhoea similar to Entamoeba dysentery with blood and mucus

40
Q

blastocystitis is caused by

A

blastocysts hominis

41
Q

blastocystitis

A
  • linked to IBS
  • 17 distinct subtypes- 9 found in humans, 4 are common
  • controversy r.e. mode of transmission/ lifecycle
42
Q

cryptosporidium

A

apicomplexan parasite.
causes diarrhoea and immune suppression
-often deadly diarrhoea disease of AIDS patients

43
Q

apicomplexan parasite

A

are a large phylum of parasitic alveolates

44
Q

two main cryptosporidium pathogens

A

C.hominis and C.parvum

45
Q

Cryptosporodium and extracytoplasmic association

A
  • sporozoites do not invade enterocyte, but attach to epithelial cells
  • induce fusion of microvilli: parasite encapsulated by house membrane
46
Q

why is cryptosporidium so dangerous

A

since the parasite is encapsulated by the host membrane- hidden from immune system

47
Q

sexual reproduction and cyrptosporidium

A
  • two rounds of asexual reproduction of zygote to generate oocysts
  • thick walled ones thought to be excreted and thin walled cysts reinfect

Healthy individuals suppress merozoites release

48
Q

fecal oral transmission

A

Cysts are resistant forms and are responsible for transmission of giardiasis. Both cysts and trophozoites can be found in the feces (diagnostic stages) (1). The cysts are hardy and can survive several months in cold water. Infection occurs by the ingestion of cysts in contaminated water, food, or by the fecal-oral route (hands or fomites) (2). In the small intestine, excystation releases trophozoites (each cyst produces two trophozoites) (3). Trophozoites multiply by longitudinal binary fission, remaining in the lumen of the proximal small bowel where they can be free or attached to the mucosa by a ventral sucking disk (4). Encystation occurs as the parasites transit toward the colon. The cyst is the stage found most commonly in nondiarrheal feces (5). Because the cysts are infectious when passed in the stool or shortly afterward, person-to-person transmission is possible. While animals are infected with Giardia, their importance as a reservoir is unclea

49
Q

cysts are.. and trophozoite are…

A

cysts are infectious and trophozoites die outside the body so do not cause illness

50
Q

cysts

A

resistant form and are responsible for the transmission of giardia

51
Q

sporozoite

A

a motile spore-like stage in the life cycle of some parasitic sporozoans (e.g. the malaria organism), which is typically the infective agent introduced into a host.

52
Q

3 types of protists concentrated on

A

Entamoeba, Cryptosporidium, Giardia

53
Q

where do giardia parasites colonise

A

upper portions of s.intestine

54
Q

adhesive disk of giardia attaches to

A

s.intestine- causes virus blunting and enterocyte apoptosis and hyper secretion of cl- and water

55
Q

apicocomplexan

A

The organelle is an adaptation that the apicomplexan applies in penetration of a host cell.

Microbiology (25 decks)

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