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BIO1337 - Microbiology > Protist Life in the Intestines > Flashcards

Protist Life in the Intestines Flashcards

1
Q

What are examples of intestinal protist?

A
  • Blastocystis hominis
  • Balantidium coli
  • Cryptosporidium
  • Giardia
  • Entamoeba
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2
Q

What are gastrointestinal symptoms?

A

Diarrhoea
Gastroenteritis
Dysentery

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3
Q

What is diarrhoea?

A

Increase in stool frequency and fluid/ loose or watery stool at least three times a day

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4
Q

What is gastroenteritis?

A

Condition that causes nausea, vomiting, diarrhoea and abdominal distress

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5
Q

What is dysentery?

A

Involved blood and mucus in stool resulting from damage to large intestine

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6
Q

What are water-/foodborne associated with?

A

Contaminated food and water

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7
Q

What does water-/foodborne lead to?

A

Dehydration, malabsoption

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8
Q

What is the second leading causes of death among children under 5 globally?

A

Diarrhoea

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9
Q

What causes diarrhoea?

A

Viruses, bacteria and protist

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10
Q

What is the purpose of GI tract?

A
  • Take up nutrients from food

- Protect rest of body from intestinal content

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11
Q

What is the pH in large intestine?

A

5.5-7.5

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12
Q

What is the pO2 in large intestine?

A

<33 mmHg

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13
Q

What is the pH in small intestine?

A

5.0-5.5

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14
Q

What is the pO2 in small intestine?

A

33 mm Hg

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15
Q

What is the pH in stomach?

A

1-4

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16
Q

What is the pO2 in stomach?

A

77 mm Hg

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17
Q

What are the 4 basic layers of GI tract?

A

Mucosa
Submucosa
Muscle layers
Serosa

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18
Q

Define enterocytes:

A

Cells in the small intestine

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19
Q

What is the microvilli on the apical surface adapted for?

A

Increases surface area for digestion and transport of molecules from intestinal lumen

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20
Q

What are the different types of diarrhoea?

A
  • Osmotic
  • Inflammatory
  • Secretory
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21
Q

What does diarrhoea result on?

A

Fluid loss and dehydration

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22
Q

What is osmotic diarrhoea?

A
  • Excessive solutes
  • Enterocyte malfunction
  • Impaired absorption
  • Enhanced secretion
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23
Q

What is inflammatory diarrhoea?

A
  • Disruption of epithelial cell barrier
  • Inflammation leads to increased permeability
  • Leukocytes in stool can lead to blood in lumen
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24
Q

What is secretory diarrhoea?

A

Toxin associated

Excessively watery

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25
Q

What are the advantages of living in the intestine?

A
  • Continual food source
  • Warm, moist environment
  • Nutrient sin simple chemical form
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26
Q

What are the challenges of living in the intestine?

A
  • Changes in pH (acidic to basic)
  • Natural mucus barrier
  • Mechanical removal peristalsis
  • Innate immune system
  • Must be motile
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27
Q

What are the two states of transmission cycles of intestinal protists?

A
  • Cyst stage

- Trophozoite stage

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28
Q

What occurs in cyst stage?

A
  • Resistant
  • Infective
  • Ingested in contained food/water
  • Cysts are excreted and are infectious
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29
Q

What occurs in trophozoite stage?

A
  • Feeding
  • Replication
  • Motile stage
  • Inhabit intestinal tract (not infectious)
  • Symptomatic stage
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30
Q

What is another name for Giardia lambilia?

A

Giardia lamblia = G. intestinalis = G. duodenalis

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31
Q

Who first submitted a drawing of Giardia lamblia?

A

Lambl

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32
Q

What are the most common protozoal parasite isolated from human stool?

A

Giardia lamblia

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33
Q

How many new cases of Giardia lamblia each year?

A

> 500,000

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34
Q

Is Giardia lamblia fatal?

A

Yes, in undeveloped countries due to untreated malabsorption and dehydration

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35
Q

How many nuclei are in cyst?

A

4

36
Q

How many nuclei are in trophozoite?

A

2

37
Q

What is the life cycle of Giardia lamblia?

A
  1. Ingestion of dormant cysts
  2. Excystation = trophozoite emerge to an active state
  3. Trophozoite undergo asexual replication
  4. Not everyone exhibits symptoms
  5. Encystation during transit toward colon
  6. Cysts and trophozoite expelled in faeces
  7. Only cysts can survive outside of host
  8. Cyst can survive for weeks/months in cold wayer
38
Q

What is excystation?

A

1 cyst produces 1 trophozoite in small intestine, followed by binary fission

39
Q

What is encystation?

A

Formation of cyst in large intestine

40
Q

How are Giardia lamblia adapted?

A
  • Trophozoites adhere to intestines
  • Absorb nutrients mainly glucose by pinocytosis or diffusion
  • Exhibits antigenic variation
  • Anaerobic (no mitochondria)
  • Sexual or asexual reproduction
41
Q

What is an adhesive disk?

A
  • Made from cytoskeleton and contractile proteins
  • Edges of disk embedded in the microvilli
  • Inhibitors of microfilaments, inhibit attachment
42
Q

How many times does Giardia switch expression?

A

Once every 10 generation

43
Q

Pathogenesis of Giardia:

A
  • Attachment could cause irritation and mucosal injury
  • Villus blunting, enterocyte apoptosis
  • Increased crypt cell activity
  • Malabsorption of nutrient
44
Q

Symptoms of Giardia:

A
  • Loss of appetite
  • Nausea
  • Explosive, watery, foul-smelling diarrhoea
45
Q

Diagnostic of Giardia:

A
  • Microscopy of cysts and trophozoites

- ELISA = Enzyme-linked immunosorbant assay

46
Q

What does Entamoeba histolytica cause?

A

Amoebic dysentery

47
Q

Global impact of Entamoeba histolytica:

A
  • Third leading cause of parasitic death
  • Infect 50 million people world wide
  • 50-100,00 deaths each year
  • Affects lower income countries
  • Can cause of traveller’s diarrhoea
48
Q

What is the life cycle of Entamoeba histolytica?

A
  1. Ingestion of contaminated food and water
  2. Mature custe form
  3. Excystation produces trophozoite
  4. Trophozoite migrate to large intestine
  5. Trophozoite multiply by binary fission
  6. Two routes
    a. Trophozoite invade intestinal mucosa = invasive infection through blood stream
    b. Encystation = immature cyst = quadrinucleate cyst = non-invasive cyst exit host in the stool
49
Q

What does histolytica mean?

A

Tissue dissolving

50
Q

What does Entamoeba histolytica invasive disease do?

A
  • Breaks through intestinal barrier to enter mucosa

- Expansion of the ulcer is limed by underlying muscle layer

51
Q

How much of Entamoeba histolytica is systematic disease?

A

1%

52
Q

How much of Entamoeba histolytica is invasive disease?

A

10%

53
Q

What does ntamoeba histolytica systemic disease do?

A

Enter blood stream and reach liver
Cause liver abscesses
Enter brain/lungs

54
Q

What did Brumpt propose?

A

Two distinct species that look identical

55
Q

What are virulence factors of Entamoeba histolytica?

A
  • Surface lectins (Gal/GalNAc lectin binds to mucin)
  • Proteases (aid mucus breakdown and invasion through extracellular matrix)
  • Pore-forming toxins (form pores in any cell membranes)
56
Q

What causes Balantidiosis?

A

Balantidium coli

57
Q

What is the only known human infectious ciliated protozoan?

A

Balantidium coli

58
Q

Is Balantidiosis common or rare?

A

Rare

59
Q

How do Balantidium coli transmit?

A

Faecal-oral route

60
Q

What is the structure of Balantidum coli?

A

Ciliate with cilia

Micro and macronucleus

61
Q

What are symptoms of Balantidum coli?

A

Diarrhoea or dysentery

62
Q

What does Balantidium coli rarely invade?

A

Intestinal epithelium

63
Q

What is the only known mammalian pathogen within stramenopiles?

A

Blastocystis hominis

64
Q

How are Blastocystis hominis transmitted?

A

Ingestion of cysts in water or on food

65
Q

What is excystation in relation to Blastocystis hominis?

A

In large intestine to generate ameboid, vascular and granular forms

66
Q

What is encystation in relation to Blastocystis hominis?

A

Formation of cyst in large intestine

67
Q

What does Blastocystis hominis produce?

A

Resistant cysts

68
Q

What is a resistant cysts?

A

Live for months in warm condistion

69
Q

Prevalence of Blastocystis hominis:

A

Common in developing countries

70
Q

Pathogenicity of Blastocystis hominis:

A

Uncertain

71
Q

Does Blastocystis hominis have extensive genetic diversity?

A

Yes

72
Q

What are the genetic subtypes of Blastocystis hominis?

A

At least 17 distinct subtypes

73
Q

How many genetic subtypes of Blastocystis hominis in humans?

A

9

74
Q

Mode of transmission of Blastocystis hominis:

A

Controversial re-transmitted between human and various animals

75
Q

When was the first Cryptosporidium recorded?

A

1976

76
Q

What are the two main human pathogens of Cryptosporidium?

A

C. hominis and C. parvum.

77
Q

What do Cryptosporidium cause in AIDS patients?

A

Deadly diarrhoeal disease

78
Q

Who is Cryptosporidium common in?

A

Immune-competent

79
Q

What are adaptions of Cryptosporidium?

A
  • Sporozoites do not invade enterocytes but attach to epithelial cell using adhesive zone
  • Induce fusion of microvilli (trophozoite encapsulated by host double membrane)
  • Hidden from immune system
80
Q

What is the life cycle of Cryptosporidium?

A
  1. Excyst in upper small bowel (4 sporozoites per cyst)
  2. Infects epithelial cells and forms trophozoite within cell
  3. Type I meront: Asexual divisions produces merozoite
  4. Type II meront: Micro- and macrogamete form zygote in sexual cycle
  5. Thick-walled cysts thought to be excreted and thin-walled cysts reinfect.
  6. Healthy individuals suppress merozoite release.
81
Q

How is Cryptosporidium transmitted?

A

Waterborne outbreaks

82
Q

What are oocysts resistant to?

A

Routine chlorine treatment

83
Q

How much oocyst Zoonotic C. parvum from animal waste produced?

A

100 billion

84
Q

What are the therapies for diarrhoeal disease?

A

-Metronidazole (Activated by anaerobic pathways)

85
Q

What is metronidazole effective against?

A
  • Giardia
  • Entamoeba
  • Trichomonas
86
Q

How do you deliver metronidazole?

A

Low osmolarity oral rehydration salts
or
Zinc tablets

87
Q

How can childhood diarrhoea be prevented?

A
  • Easily preventable
  • Personal hygiene
  • Treatment of asymptomatic household members
  • Public health

BIO1337 - Microbiology (18 decks)

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