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First Aid Microbiology > Bugs with exotoxins > Flashcards

Bugs with exotoxins Flashcards

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Biology 101 flashcards
1
Q

Name 4 toxins that inhibit protein synthesis?

A
  1. Diphteria toxin from Corynebacterium diphtheriae
  2. Exotoxin A from Pseudomonas aeruginosa
  3. Shiga toxin from Shigella
  4. Shiga like toxin from Enterohemorrhagic E. coli (EHEC) including O157:H7
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2
Q

Among the 4 toxins that inhibit protein synthesis what 2 toxins inactivate elongation factor?

A
  1. Diphtheria toxin

2. Exotoxin A

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3
Q

Among the 4 toxins that inhibit protein synthesis what 2 toxins inactivates 60S ribosome by removing adenine from rRNA?

A
  1. Shiga toxin

2. Shiga-like toxin

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4
Q

What is the clinical consequence of Diphtheria toxins from Corynebacterium diphtheriae?

A

Pharyngitis with pseudomembranes in throat and severe lymphadenopathy (bull neck)

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5
Q

What is the clinical consequence of Exotoxin A from Pseudomonas aeruginosa?

A

Host cell death

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6
Q

What is the clinical manifestation of shiga toxin from shigella?

A
  1. GI mucosal damage –> dysentery

2. Shiga toxin also enhances cytokine release –> hemolytic uremic syndrome (HUS)

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7
Q

What is the clinical manifestation of shiga like toxin from EHEC (O157:H7)?

A

SLT enhances cytokine release –> HUS, but no invasion of host cells, no GI mucosal damage –> thus no dysentery

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8
Q

What are the 4 toxins that increase fluid secretion?

A
  1. Heat-labile toxin from Enterotoxigenic E. coli (ETEC)
  2. Heat-stable toxin from ETEC
  3. Edema factor from Bacillus anthracis
  4. Cholera toxin from Vibrio cholerae
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9
Q

What is the mech of heat-labile toxin from Enterotoxigenic E. coli (ETEC)?

A

Overactivates adenylate cyclase (Inc cAMP) –> Inc Cl- secretion in gut and H2O efflux

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10
Q

What is the mech of heat-stable toxin from ETEC?

A

Overactivates guanylate cyclase (Inc cGMP) –> Dec resorption of NaCl and H2O in gut

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11
Q

What is the clinical manifestation of both heat-labile and heat-stable toxin?

A

Watery diarrhea
(labile in the Air, Adenylate cyclase)
(stable on the Ground, Guanylate cyclase)

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12
Q

what is the mech of edema factor from Bacillus anthracis

A

mimics the adenylate cyclase enzyme –> Inc cAMP

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13
Q

what is the clinical manifestation of the edema factor from Bacillus anthracis?

A

likely responsible for characteristic edematous borders of black eschar in cutaneous anthrax

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14
Q

what is the mech of cholera toxin from vibrio cholerae?

A

Overactivates adenylate cyclase (Inc cAMP) by permanently activating Gs –> Inc Cl- secretion in gut and H2O efflux

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15
Q

what is the name of a toxin that inhibits phagocytic ability?

A

Pertussis toxin from Bordetella pertussis

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16
Q

what is the mech of pertussis toxin from Bordetella pertussis?

A

overactivates adenylate cyclase (Inc cAMP) by disabling Gi, impairing phagocytosis to permit survival of microbe

17
Q

what is the clinical manifestation of pertussis toxin from Bordetella pertussis?

A

whooping cough: child coughs on expiration and “whoops” on inspiration (toxin may not actually be a cause of cough; can cause 100 day cough in adults)

18
Q

what are the toxins that inhibit release of neurotransmitter?

A
  1. Tetanospasmin from Clostridium tetani

2. Botulinum toxin from Clostridium botulinum

19
Q

what are the toxins that are ADP ribosylating A-B toxin?

A
  1. Cholera toxin
  2. Pertussis toxin
  3. Heat-labile toxin from Enterotoxigenic E. coli (ETEC)

And all the toxins that inhibit protein synthesis

  1. Diphtheria toxin
  2. Exotoxin A
  3. Shiga toxin
  4. Shiga-like toxin
20
Q

what is the mech of ADP ribosylating A-B toxin?

A
  1. B (binding) component binds to host cell surface receptor, enabling endocytosis.
  2. A (active) component attaches ADP-ribosyl to disrupt host cell proteins.
21
Q

what is the mech of tetanospasmin and botulinum toxin?

A

both are proteases that cleaves SNARE proteins required for neurotransmitter release

  1. tetanospasmin –> prevents the release of inhibitory (GABA and glycine) neurotransmitter from Renshaw cells in spinal cord
  2. botulinum toxin –> prevents release of stimulatory (ACh) signals at neuromuscular junctions –> flaccid paralysis
22
Q

what is the clinical manifestation of tetanospasmin from Clostridium tetani?

A

Spasticity, risus sardonicus, and lockjaw

similar to UMN lesions = spastic paralysis

23
Q

what is the clinical manifestation of botulinum toxin from Clostridium botulinum?

A

Flaccid paralysis (similar to LMN lesion), floppy baby (Spinal muscular atrophy (Werdnig- Hoffmann disease))

24
Q

what are the 2 toxins that lyse cell membrane?

A
  1. alpha toxin from Clostridium perfringens

2. streptolysin O from streptococcus pyogens

25
Q

what is the mech of alpha toxin from Clostridium perfringens?

A

phospholipase (lecithinase) that degrades tissue and cell membranes

26
Q

what is the mech of streptolysin O?

A

protein that degrades cell membrane

27
Q

what are the clinical manifestations of alpha toxin from Clostridium perfringens?

A

Degradation of phospholipids –> myonecrosis (“gas gangrene”) and hemolysis (“double zone” of hemolysis on blood agar)

28
Q

what are the clinical manifestations of streptolysin O from Streptococcus pyogens?

A
  1. Lyses RBC

2. contributes to beta hemolysis

29
Q

Host antibodies against toxin ASO is used to diagnose which dz?

A

Rheumatic fever

30
Q

what are the 2 superantigens that cause shock?

A
  1. Toxic shock syndrome toxin (TSST-1) from Staphylococcus aureus
  2. Exotoxin A from Strep. pyogens
31
Q

what is the mech of the 2 toxins, toxic shock syndrome toxin (TSST-1) and Exotoxin A?

A

Bring MHC II and TCR in proximity to outside of antigen binding site to cause overwhelming release of IFN-gamma and IL-2 –> shock

32
Q

what are the clinical manifestations of toxic shock syndrome?

A

fever, rash, shock

33
Q

what toxin causes scalded skin syndrome?

A

exfoliative toxin

34
Q

what toxin cause food poisoning?

A

enterotoxin

35
Q

what is endotoxin?

A

an LPS found in outer membrane of gram negative bacteria (both cocci and rods)

36
Q

ENDOTOXIN:

A 
Edema
Nitric oxide
DIC/Death
Outer membrane
TNF-alpha
O-antigen
eXtremely heat stable
IL-1
Neutrophil chemotaxis
37
Q

what particular component in endotoxin triggers the immune system?

A

lipid A

38
Q

what are the 3 immune systems that endotoxin (lipid A) activates?

A
  1. macrophage
  2. complement
  3. tissue factor –> coagulation cascade –> DIC
39
Q

once endotoxin lipid A activates macrophage, what components are then further activated?

A
  1. IL-1 –> fever
  2. TNF –> fever, hypotension
  3. Nitric oxide –> hypotension

First Aid Microbiology (15 decks)

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