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micro quiz 2 > MICR_040913 Ecoli > Flashcards

MICR_040913 Ecoli Flashcards

1
Q

Enteric E. coli serves these purposes:

A

vitamin K production and protection against other pathogens

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2
Q

How do some enteric E. coli become pathogenic?

A

it acquired virulence genes via horizontal gene transfer

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3
Q

What are the diarrhegenic E. coli?

A

EPEC, EAEC, EIEC, ETEC (think: PATI)

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4
Q

What are the shiga-producing E. coli?

A

EHEC

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5
Q

What does EPEC stand for?

A

enteroPATHOGENIC e. coli

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6
Q

What does EAEC stand for?

A

enteroAGGREGATIVE e. coli

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7
Q

What does EIEC stand for?

A

enteroINVASIVE e. coli

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8
Q

What does ETEC stand for?

A

enteroTOXIGENIC e. coli

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9
Q

What does EHEC stand for?

A

enteroHEMORRHAGIC e. coli

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10
Q

What is the main serogroup for EHEC?

A

O157:H7

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11
Q

How is EHEC spread?

A

via contaminated foods and person:person contact

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12
Q

What are the symptoms of EHEC?

A

abdominal pain, bloody diarrhea, hemolytic uremic syndrome (HUS)

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13
Q

What is HUS characterized by?

A

Hemolytic Uremic Syndrome; due to Shiga-like toxin. Causes hemolytic anemia, low platelet count, and may lead to renal failure

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14
Q

T/F EHEC spreads via blood.

A

False. It does not spread through blood (no bacteremia)

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15
Q

What is the LEE pathogenicity island? (7)

A

genes that cause attachment/effacing lesions: 1) T3SS, 2) Intimin/Tir, 3) Shiga like toxin, 4) hemolysin, 5) capsule (K antigen), 6) LPS (endotoxin), and 7) nutrient acquisition pathways (ie siderophores)

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16
Q

What is the LEE pathogenicity island ultimately cause?

A

attachment/effacing lesions “A/E lesions”

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17
Q

What is T3SS?

A

system that enhances host cell attachment via EspA and EspB/D. (EspA = “needle” for espB/D to pass, ESPB/D = forms a pore on host membrane)

18
Q

What is Intimin/Tir?

A

recruits host proteins that lead to actin polymerization; ultimately casuses destruction of host cell microvilli (EFFACEMENT)

19
Q

What is Shiga-like toxin? What is it also known as?

A

aka Verotoxin - affects protein synthesis (A) and cytoskeletal integrity (B). Causes HUS

20
Q

What is hemolysin?

A

pore-forming protein

21
Q

Why is it that cattle can carry EHEC without getting sick, while humans can’t?

A

Shiga-toxin B subunit binds to a protein Gb3/CD77 on host cells and this is not present in cattle

22
Q

Which E. coli affects the LARGE intestines?

A

EHEC, EIEC (think HI - love getting BIG hellos)

23
Q

Which E. coli affects the SMALL intestines?

A

EPEC, EAEC, ETEC (think: PAT - pattie cakes are small)

24
Q

What E. coli is responsible for the leading cause of death in developing countries?

A

EPEC

25
Q

EPEC produces these virulence factors:

A

T3SS, Tir/intimin, bundle forming Pili (BFP)

26
Q

What is Bundle Forming Pili (BFP)?

A

produced by EPEC, required for localized adherence to epithelial cells and auto-aggregation

27
Q

Which two E. coli strains produce A/E lesions?

A

EHEC and EPEC (think HP is a big printer company that can cause a lot of damage if it falters)

28
Q

Which E. coli strain causes travelers and infants diarrhea in developing countries?

A

ETEC

29
Q

ETEC produces these 3 key virulence factors:

A

1) fimbrae (for colonization), 2) Heat Labile Toxin (increases cAMP), 3) Heat Stable Toxin (increases cGMP)

30
Q

What is heat-labile toxin (LT)? Who produces them?

A

produced by ETEC; increases cAMP, which increases Cl- secretion, thereby decreasing Na+ uptake. Leads to a net fluid of fluid and electrolytes (watery diarrhea)

31
Q

What is heat-stable toxin (ST)? Who produces them?

A

produced by ETEC; increases cGMP, which result in similar outcomes to heat-labile toxins

32
Q

What strain of E. coli produce persistent diarrheas that can lead to weight loss?

A

EAEC (think: the gunner E. coli is type “A” because it must produce the worst diarrheas possible to be successful)

33
Q

Why is it that EAEC causes more persistent diarrheas?

A

it is more aggressive due to higher affinity colonization factors

34
Q

T/F EHEC, EAEC, and EPEC produce A/E lesions.

A

False! Only EHEC and EPEC produces A/E lesions (think HP is a big printer company that can cause a lot of damage if it falters)

35
Q

EAEC produces these 2 key virulence factors:

A

1) Enteroaggressive stable toxin (EAST), and 2) hemolysin

36
Q

Which E. coli is most common in developing countries?

A

EIEC (think I for international)

37
Q

What is the pathogenesis of EIEC?

A

attaches and invades mucosal cells in the colon via non-fimbrial adhesions (highly invasive)

38
Q

What are the symptoms of EIEC?

A

watery diarrhea with blood and mucous (like Shigella dysentery)

39
Q

What is DAEC?

A

Diffuse-Adhering E. Coli - causes diarrhea in developing countries, but is poorly characterized

40
Q

What are some diagnostics that you can use to determine different strains of E. coli?

A

PCR for virulence factors, immunoassays for toxins, serology for surface antigens

41
Q

What is a diagnostic that you can use to determine between commensel and pathogenic E. coli?

A

Sorbitol MacConkey Agar: pathogenic O157:H7 = no growth/sorbitol (-); COMMENAL = growth/sorbitol (+)

micro quiz 2 (8 decks)

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