GI Infectious Diseases Flashcards

1
Q

What percentage of children under 5 dying is caused by diarrhoea? Pneumonia?

A

diarrhoea: 11%
pneumonia: 18%

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2
Q

why does diarrhoea kill

  1. immediately
  2. delayed?
A
  1. fluid and electrolyte loss

2. malnutrition

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3
Q

Which bugs have a 20x higher death rate post infection?

A

ecoli, shigella, parasites

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4
Q

33% of all children deaths are caused by?

A

malnutrition

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5
Q

2 ways diarrhoea causes malnutrition?

A
  1. increased energy loss

2. reduced energy intake

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6
Q

2 reasons for reduced energy intake in diarrhoea?

A

malabsorption post gut damage

withholding of food (moms think breast milk caused it)

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7
Q

how is Gut damage in kids different than adults?

A

kids guts repair slower

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8
Q

out of 10 litres of liquid consumed in 24 hours, how much is absorbed?

A

9.9 litres

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9
Q

what is the reserve capacity of the GIT for fluids?

A

4-5 litres

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10
Q

what happens if you surpass the reserve capacity of the GIT for fluid?

A

diarrhoea

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11
Q

3 aetiological agents of diarrhoea?

A

bacteria
viruses
protozoa

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12
Q

What is the predominant cause of diarrhoea in developed countries?

A

Viral 40%

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13
Q

What is the predominant cause of diarrhoea in developing countries?

A

bacterial (35%)

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14
Q

Gastroenteritis generally just means?

A

vomiting and diarrhoea

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15
Q

dysentery needs to have?

A

blood, pus, mucous in the feces

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16
Q

enteroinvasive ecoli AKA:

A

shigella

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17
Q

shigella causes what kind of diarrhoea?

A

dysentery

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18
Q

what does entamoeba histolytica cause? what is it?

A

protozoal cause of dysentery

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19
Q

Which foods do you find staph and salmonella poisoning in?

A

Mayonnaise (raw eggs)

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20
Q

Listeria outbreaks recently in which foods?

A

soft cheeses

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21
Q

clostridium perfringes, bacillus, vibrio are from what kind of syndrome?

A

food poisoning

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22
Q

ciguatoxin si dangerous why?

A

can kill

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23
Q

Traveller’s diarrhoea mainly caused by?

A

ETEC, bac, viruses, protozoa

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24
Q

What causes atibiotic-associated colitis?

A

Clostridium difficile

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25
Q

What the difference between dysentery and haemorrhagic colitis?

A

No pus in the faeces

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26
Q

main bug that causes haemorrhagic colitis?

A

EHEC (entero-hemorrhagic e.coli)

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27
Q

What causes cholera-like symptoms?

A

vibrio cholerae, ETEC

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28
Q

enteric fevers are local or systemic?

A

systemic

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29
Q

Which 2 bugs cause enteric fever?

A

salmonella typhi

salmonella paratyphi

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30
Q

What is ETEC?

A

enterooxigenic E. coli

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31
Q

What is EPEC?

A

Enteropathogenic E. coli

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32
Q

What is EHEC?

A

enterohaemorrhagic E. coli

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33
Q

what is EIEC?

A

enteroinvasive E. coli

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34
Q

what is EAEC?

A

enteroaggregative E. coli

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35
Q

What are the adhesins for ETEC?

A

CFAs

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36
Q

What are the adhesins for EPEC?

A

intimin, Bfp

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37
Q

What are the adhesins for EHEC

A

intimin and Efa

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38
Q

EHEC evolved from?

A

EPEC

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39
Q

What are the adhesins for EAEC?

A

AAF

40
Q

Which ecoli can secrete shiga toxin?

A

EHEC?

41
Q

shiga toxin is AKA?

A

verotoxin

42
Q

which two ecoli cause watery diarrhoea?

A

ETEC

EAEC

43
Q

which ecoli causes bloody diarrhoea?

A

EHEC

44
Q

what does EIEC cause?

A

dysentery

45
Q

EPEC causes?

A

non-specific gastro

46
Q

5 levels of invasion of mucosa?

A
  1. adhesive enterotoxigenic
  2. adhesive with bush border damage
  3. invasion restricted to muscosa
  4. invasion of submucosa
  5. systemic invasion
47
Q

Bugs that are adhesive enterotoxigenic?

A

cholera, ETEC

48
Q

Bugs that are adhesive enterotoxigenic adhesive with bush border damage?

A

EPEC

49
Q

Bugs that are invasion restricted to muscosa

A

shigella

50
Q

Bugs that are invasion of submucosa

A

salmonella

capylobacter

51
Q

Bugs that are systemic invasion?

A

salmonella

52
Q

What happens if immunocompromised patient has invasion of submucosa bugs like: salmonella
capylobacter?

A

could turn systemic

53
Q

EPEC has two stages of adherence they are?

A
  1. plasmid mediated

2. chromosomal (attachment)

54
Q

where do you find bundle forming pili?

A

stage one plasmid mediated adherence of EPEC only

55
Q

Do mammals use Type III secretion systems?

A

Nope. ONLY pathogens

56
Q

Why is Type III secretion system for pathogens special?

A

gets a protein DIRECTLY from bacterial cytoplasm to host cytoplasm via small ‘syringe’

57
Q

the Tir and Intimin combo is unique in nature for the following reason?

A

TIR = translocated intimin receptor

essentially e.coli secretes it’s own receptor onto our cells so that their intimin can adhere to our cells

58
Q

Which shigella is the worst and the only one that produces shiga toxin?

A

shigella dysenteriae

59
Q

do ALL shigella dysenteriae produce shiga toxin?

A

Nope.

60
Q

Do ALL EHEC produce shiga toxin?

A

yes by definition

61
Q

what does HUS stand for?

A

Haemolytic urea syndrome

62
Q

Haemolytic urea syndrome caused by which toxin?

A

NEED shiga toxin

63
Q

4 Virulence Determinants?

A

adhesins
invasive ability
exotoxins
ability to resist killing

64
Q

3 pathogens that are invasive?

A

shigella
salmonella
yersinia

65
Q

2 kinds o adhesins?

A

fimbriae

non-fimbriate

66
Q

2 kinds of exotoxins?

A

cytotonic: cholera
cytotoxic: shiga

67
Q

2 ways to resist killing?

A
resist serum
resist phagocytes (eg. salmonella, macrophages)
68
Q

are there microvilli on immature enterocytes?

A

Nope

69
Q

after damage by rotavirus, what happens to intestinal architecture?

A

flattening of microvilli/improper absorption

70
Q

do labs culture viruses?

A

only for the more common ones

71
Q

5 things the lab does to diagnose pathogens?

A
macroscopic appearance
microscopy
culture
antigen detection
detection of nucleic acid
72
Q

Would you see bacteria with amoeboid infection? Why?

A

Nope, because amoebas eat bacteria!

73
Q

Trophozoites of Giarbia lamblia are found where usually?

A

proximal small intestine, then let go an move down the gut making cysts along the way

74
Q

In active trophozooite of Entamoeba histolytica, what the smoking gun in the diagnosis?

A

RBCs ingested by the amoeba on light microscope

75
Q

Entamoeba histolytica can live as two things

A

commensal and pathogen

76
Q

3 ways to culture faeces

A

enrichment (salmonella)
direct plating on selective/indicator media
confirm suspicious colonies

77
Q

3 ways to confirm suspicious colonies?

A

biochem tests (virulence typing)
serotyping (EHEC0157, salm.typhi)
pathotyping (PCR)

78
Q

What the last resort for viral infection diagnosis?

A

electron microscopy

79
Q

3 ways to diagnose viral infections

A

antigen detection
detection of nucleic acid
electron microscopy

80
Q

Eg. of when you would use capture assay for antigen?

A

rotavirus from a faeces sample

81
Q

Viral nucleic acids by PCR revealed by?

A

electrophoreses

82
Q

2 best treatments for diarrhoea?

A
  1. fluid and electrolyte replacement

2. reduce fluid loss

83
Q

Why give electrolytes with fluid?

A

electrolytes help the body uptake water as water and other ions follow Na+

84
Q

3 kinds of anti-diarrhoeals? (do they work?)

A
antimotility (still diarrhoea-ing on inside)
anti-secretory agents (doesn't work)
binding agents (does stop it, just looks better)
85
Q

Is shiga toxin dangerous to non-humans?

A

Not as dangerous as they have the shiga toxin receptor and only destroys a few gut cells

86
Q

Why is shiga toxin dangerous to humans?

A

we don’t have a shiga toxin receptor so it can pass straight through and cause havoc on brain/heart etc.

87
Q

Antibiotics for diarrhoea, what does it do for cholera?

A

shortens illness a smidge

88
Q

which systemic infection MUST you treat with Antibiotics for diarrhoea?

A

typhoid fever

89
Q

Antibiotics for diarrhoea for immunocompromised patients?

A

yes

90
Q

treat shigella dystenteriae with antibiotics?

A

yes indeed

91
Q

Would you treat someone with a protozoal infection even if they feel fine?

A

Yes. Always treat

92
Q

Why is pseudomembranous colitis treatment paradoxical?

A

treatment is antibiotic (metronidazole)

caused by: antibiotics

93
Q

WHO two best ways to reduce incidence of diarrhoea?

A
  1. education: hygiene, breast-feeding

2. immunisation

94
Q

3 ways to prevent traveller’s diarrhoea?

A

reduce exposure
antimicrobials (maybe)
immunisation (active/passive)

95
Q

what’s the function of bundle forming pili?

A

prevent washing away of pathogen due to peristalsis

96
Q

LEE pathogenicity island stands for?

A

Locus of Enterocyte Effacement

97
Q

EPEC and EHEC both made which two adherins?

A

intimin and LEE