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M1 Micro Quiz 2 > E. Coli > Flashcards

E. Coli Flashcards

1
Q

what are the main serogroups of Enterohemorrhagic E. coli (EHEC, STEC)?

A 
O157:H7
O111
O26
O157:H-
O104:H4
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2
Q

what are the sources of EHEC & STEC infection?

A

food (undercooked/unpasteurized)
petting zoos
person to person
very low infectious dose

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3
Q

Describe Enterrohemorrhagic (EHEC & STEC) clinical syndrome.

A 
abdominal pain
bloody diarrhea
can lead to hemolytic uremic syndrome
acute renal failure (usu. children <10)
generally extracellular
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4
Q

Describe Enterrohemorrhagic (EHEC & STEC) pathogenesis - what tools does the bacteria have to cause disease?

A 
pili-mediated attachment
T3SS
Intimin
recruit host cell actin causing altered morphology
shiga-like toxin
capsule
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5
Q

What are the aspects of Enterrohemorrhagic (EHEC & STEC) virulence - what does it do in the body to cause disease?

A
  • actin disruption results in altered morphology and impacts signal transduction pathways forming A/E lesions
  • lesions lead to loss of microvilli (effacement)
  • Shiga like toxin disrupts eukaryotic protein synthesis and causes hemolytic uremic syndrome
  • hemolysin
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6
Q

what is Tir? what does it allow E. coli to do?

A

a T3SS secreted bacterial protein that is delivered to surface of epithelial cells to allow for E. coli attachment

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7
Q

what is Intimin? (E. coli)

A

Tir binding protein on surface of E. coli

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8
Q

what is Shiga-like toxin? how is it toxic?

A

gene found on phage
disrupts eukaryotic protein synthesis via RNA cleavage activity
causes hemolytic uremic syndrome

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9
Q

what is Hemolysin? (E. coli) where is it encoded?

A

pore forming protein that inserts into host cell membrane

encoded by a plasmid

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10
Q

what are the Diarrheagenic strains of E. coli?(5)

A 
Enteropathogenic (EPEC)
Enterotoxigenic (ETEC)
Enteroaggregative (EAEC)
Enteroinvasive (EIEC)
Diffuse adhering (DAEC)
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11
Q

How is Enteropathogenic E. coli (EPEC) transmitted?

A

Overt human pathogen transmitted by person-to-person contact

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12
Q

How it Enterotoxigenic E. coli (ETEC) transmitted?

A

From food and water

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13
Q

what type of e. coli produces a heat-labile toxin? how does this toxin act? what is the clinical consequence?

A

Enterotoxigenic E. coli (ETEC)

  • targets adenylate cyclase leading to increased cAMP levels that result in excess chloride ion secretion and blocked sodium ion uptake
  • leads to net loss of fluid and electrolytes in gut and watery diarrhea
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14
Q

what type of e. coli produces a heat-stable toxin? how does this toxin act? what is the clinical consequence?

A
  • Enterotoxigenic E. coli (ETEC)

- alters cGMP levels leading to fluid and electrolyte loss through watery diarrhea

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15
Q

what types of disease does Enteroaggregative E. coli (EAEC) cause?

A
  • Diarrheagenic
  • Childhood diarrhea/Chronic diarrhea
  • persistent diarrhea that can lead to weight loss
  • No A/E lesions
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16
Q

how is Enteroinvasive E. coli (EIEC) transmitted?

A

From contaminated food

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17
Q

what diseases does diffuse adhering E. coli (DAEC)? in what types of patients and where? what is know about it?

A

Diarrhea in older children in developing countries

poorly characterized

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18
Q

how would you diagnose E. coli?

  • what would you see in a lactose test?
  • sorbitol test?
  • immunoassay?
  • PCR?
A
  • Lac+
  • O157:H7 cannot grow on sorbitol while commensal E. coli are sorbitol-positive
  • Immunoassay for shiga-like toxin
  • do strain typing with PCR or DNA probe analysis
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19
Q

how can you prevent E. coli spread and infection?

A
  • Hygiene

- Hay fed cattle are less likely to harbor E. coli than grain fed cattle due to higher stomach pH

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20
Q

how are STEC & EHEC (Shiga toxin and Enterohemorrhagic) diagnosed?

A
  • PCR/immunoassay for shiga toxin
  • Nucleic acid detection of virulence genes
  • EHEC-sorbitol fermentation
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21
Q

how is ETEC (Enterotoxigenic) diagnosed?

A
  • Nucleic acid detection of virulence genes
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22
Q

how is EPEC (Enteropathogenic) diagnosed?

A
  • Nucleic acid detection of virulence genes or tissue culture assay for aggregative adherence
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23
Q

how is EAEC (Enteroaggregative) diagnosed?

A

Nucleic acid detection of virulence genes or tissue culture assay for aggregative adherence

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24
Q

how is EIEC (Enteroinvasive) diagnosed?

A

Nucleic acid detection of virulence genes

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25
Q

how is DAEC (Diffuse adhering) diagnosed?

A

Tissue culture assay for diffuse adherence

26
Q

Are Enteropathogenic toxins detected in stool?

A

No

27
Q

Where and in whom is Enteropathogenic E. coli (EPEC) common? what does it cause?

A
  • Leading cause of childhood diarrhea in developing countries
  • Forms A/E lesions
  • Diarrheagenic
28
Q

how does Enteropathogenic E. coli (EPEC) adhere?

A

Localized adherence by bundle forming pili

29
Q

what diseases does Enterotoxigenic E. coli (ETEC) cause?

A
  • Diarrheagenic

- Traveler’s Diarrhea

30
Q

how does Enterotoxigenic E. coli (ETEC) adhere to cells?

A

Fimbriae adhere to receptors on enterocytes of small intestine

31
Q

What are the toxins carried by Enterotoxigenic E. coli (ETEC)?

A

Head-labile toxin and Heat-stable toxin

32
Q

what is the consequence of Enteroaggregative E. coli (EAEC) colonization factors?

A

colonization factors can lead to more aggressive epithelial cell attachment
No A/E lesions

33
Q

is Enteroaggregative E. coli (EAEC) invasive?

A

Non-invasive

34
Q

what kinds of toxins does Enteroaggregative E. coli (EAEC) produce?

A

Heat stable-like toxin, Pet toxin, hemolysin

35
Q

where is Enteroinvasive E. coli (EIEC) found?

A

Less common in industrialized nations

36
Q

how does Enteroinvasive E. coli (EIEC) adhere to and invade cells?

A

attaches in colon by non-fimbrial adhesins

invades mucosal cells

37
Q

is Enteroinvasive E. coli (EIEC) systemic?

A

non-systemic

38
Q

what diseases does Enteroinvasive E. coli (EIEC) cause?

A

watery diarrhea with blood and mucus (similar to Shigella)

39
Q

what toxins does Enteroinvasive E. coli (EIEC) produce?

A

Do not produce heat-labile or heat-stable toxin

40
Q

how are STEC & EHEC (Shiga toxin and Enterohemorrhagic) treated?

A
  • Supportive treatments

- Antibiotics contraindicated

41
Q

how is ETEC (Enterotoxigenic) treated?

A
  • Loperamide (can be combined with fluoroqinolones)
  • Azithromycin
  • rifaximin
42
Q

how is EPEC (Enteropathogenic) treated?

A

Antibiotics guided by susceptibility testing for severe cases

43
Q

how is EAEC (Enteroaggregative) treated?

A

Fluoroquinolones for travelers and HIV patients

44
Q

Where and in whom is Enteropathogenic E. coli (EPEC) common? what does it cause?

A
  • Leading cause of childhood diarrhea in developing countries
  • Forms A/E lesions
  • Diarrheagenic
45
Q

how does Enteropathogenic E. coli (EPEC) adhere?

A

Localized adherence by bundle forming pili

46
Q

what diseases does Enterotoxigenic E. coli (ETEC) cause?

A
  • Diarrheagenic

- Traveler’s Diarrhea

47
Q

how does Enterotoxigenic E. coli (ETEC) adhere to cells?

A

Fimbriae adhere to receptors on enterocytes of small intestine

48
Q

how does Enterotoxigenic E. coli (ETEC) respond to heat?

A

Head-labile toxin and Heat-stable toxin

49
Q

what is the consequence of Enteroaggregative E. coli (EAEC) colonization factors?

A

colonization factors can lead to more aggressive epithelial cell attachment
No A/E lesions

50
Q

is Enteroaggregative E. coli (EAEC) invasive?

A

Non-invasive

51
Q

what kinds of toxins does Enteroaggregative E. coli (EAEC) produce?

A

Heat stable-like toxin, Pet toxin, hemolysin

52
Q

where is Enteroinvasive E. coli (EIEC) found?

A

Less common in industrialized nations

53
Q

how does Enteroinvasive E. coli (EIEC) adhere to and invade cells?

A

attaches in colon by non-fimbrial adhesins

invades mucosal cells

54
Q

is Enteroinvasive E. coli (EIEC) systemic?

A

non-systemic

55
Q

what diseases does Enteroinvasive E. coli (EIEC) cause?

A

watery diarrhea with blood and mucus (similar to Shigella)

56
Q

what toxins does Enteroinvasive E. coli (EIEC) produce?

A

Do not produce heat-labile or heat-stable toxin

57
Q

how are STEC & EHEC (Shiga toxin and Enterohemorrhagic) treated?

A
  • Supportive treatments

- Antibiotics contraindicated

58
Q

how is ETEC (Enterotoxigenic) treated?

A
  • Loperamide (can be combined with fluoroqinolones)
  • Azithromycin
  • rifaximin
59
Q

how is EPEC (Enteropathogenic) treated?

A

Antibiotics guided by susceptibility testing for severe cases

60
Q

how is EAEC (Enteroaggregative) treated?

A

Fluoroquinolones for travelers and HIV patients

M1 Micro Quiz 2 (12 decks)

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