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MSII: Microbiology Unit 6 > Enteric Bactieria 1 (1) > Flashcards

Enteric Bactieria 1 (1) Flashcards

1
Q

Describe the following for Shigella:

Gram stain
Fermenting
H2S status
Mobility
Respiration
A 
Gram (-) rod
Non-lactose fermenting
H2S (-)
Nonmotile
Facultative Anaerobe
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2
Q

What lab technique can halp differentiate E. coli and Shigella?

A

MacConkey Agar

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3
Q

How does MacConkey Agar work?

A

It selects for lactose fermenters (E. coli)

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4
Q

Describe the infectious dose of Shigella?

A

Very low (<100 IUs)

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5
Q

What are two possible complications of Shigella?

A

1- Reiters syndrome

2- HUS

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6
Q

What cells does shigella invade?

A

Distal ilium and colon epithelium

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7
Q

How does shigella escape macrophages?

A

It induces apoptosis of macrophages

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8
Q

How does Shigella infect cells once it has escaped macrophages?

A

T3SS mediated entry into the backside of intestinal epithelial cells and neighboring cells

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9
Q

What is the mechanism of the shiga toxin?

A

Protein systhesis inhibition

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10
Q

Where is the shiga toxin encoded?

A

plasmid

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11
Q

What causes HUS?

A

Shiga toxin escapes into bloodstream

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12
Q

What occurs in the pathogenesis of HUS?

A

Shiga toxin sets off a immunological/hematological cascade leading to acute hemolysis, renal failure, uremia, and disseminated intravascular coagulation (DIC)

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13
Q

Symptoms of shigella?

A

Fever, dehydration, severe headache, lethargy, diarrhea progresses from watery to bloody with mucus

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14
Q

Symptoms of HUS?

A

Fever, dehydration, hemolysis, thrombocytopenia, uremia requiring dialysis

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15
Q

What age group is most effected by Shigella ?

A

The young (particularly <5yo)

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16
Q

What can host factor can worsen a shigella infection?

A

Malnourishment

17
Q

What laboratory results are diagnostic of HUS?

A

Schistocytes, Decreased platelets, increased PMNs increased lactate dehydrogenase

18
Q

Treatment for shigella?

A

Rehyrdrate!

No anti-diarrheals

Antibiotics once r/o E. coli

19
Q

Describe the following for E. coli:

Gram stain
Fermenting
H2S status
Mobility
Respiration
A 
Gram (-) rod
Lactose fermenting
H2S (-)
Motile or non-motile
Facultative anaerobe
20
Q

What GI symptoms/ diarrheal illnesses are caused by the following E. coli strains?

Enterotoxigenic E. coli (ETEC)

Enteropathogenic E. coli (EPEC)

Enteroinvasive E. coli (EIEC)

Enterohemorrhagic E. coli (EHEC)

A

Enterotoxigenic E. coli (ETEC) is a cause of traveler’s diarrhea.

Enteropathogenic E. coli (EPEC) is a cause of childhood diarrhea

Enteroinvasive E. coli (EIEC) causes a Shigella-like dysentery.

Enterohemorrhagic E. coli (EHEC) is infected by phage STX, produces Shiga toxin, causes hemorrhagic colitis or hemolytic-uremic syndrome (HUS).

21
Q

Name some virulence factors of E. coli

A

T3SS

T4SS

Shiga toxin

Enterotoxins

Pili/ fimbrae

22
Q

What is the mechanism of the enterotoxin of E. coli?

A

It is an exotoxin that forces host ells to release fluids (and K+)

23
Q

T/F: HUS is a purely toxigenic process.

A

True

24
Q

What are 2 important factors that influence the development of HUS?

A

1- Capillary occlusion

2- Cytokine dysregulation (increased)

25
Q

Where in the GI does Enterotoxigenic E. coli (ETEC) pili attach?

A

jejunum and ileum

26
Q

Where in the GI does EHEC pili attach?

A

Mucosal epithelial cells of the colon

27
Q

Treatment for ETEC infection?

A

rehydration

28
Q

Treatment for EHEC?

A

NO antimotility agents

Antibiotics associated with increased HUS risk (opposite of Shigella!)

Just Rehydration

29
Q

Name 3 agents that can cause noninfectious bacterial-toxigenic foodborne disease?

A

S. aureas

Bacillus cereus

Clostridium botulinum

30
Q

Which toxigenic gastroenteritis is associated with “protein” sources?

A

S. aureas

31
Q

Which toxigenic gastroenteritis is associated with friend rice?

A

Bacillus cereus

32
Q

What toxigenic gastroenteritis is associated with airtight packed food?

A

Clostridium botulinum

33
Q

How can you tell the difference between infectious and non-infectious gastroenteritis?

A

Non-infectious/ Toxigenic begins HOURS later instead of days later

MSII: Microbiology Unit 6 (10 decks)

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