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Microbiology > Exotoxins And Endotoxins > Flashcards

Exotoxins And Endotoxins Flashcards

1
Q

Exotoxin source

A

Gram + and gram - bacteria

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2
Q

Endotoxin source

A

Outer-membrane of gram (-) bacteria

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3
Q

Chemistry of exotoxin

A

It’s polypeptide

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4
Q

Chemistry of Endotoxin

A

Its’ lipid A component pf LPS ( structural part of the bacteria, released when lysed )

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5
Q

Location of gene of exotoxin and endotoxin

A
  1. Exotoxin : plasmid or bacteriophage

2. Endotoxin : bacterial chromosome

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6
Q

Rate of Adverse effect of exotoxin and endotoxin

A
  1. Exotoxin : high

2. Endotoxin: low

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7
Q

Clinical effects of endotoxin

A
  1. Fever
  2. Shock (hypotension )
  3. DIC
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8
Q

Vaccine of endotoxin and exotoxin

A
  1. Exotoxin: toxoids

2. Endotoxin : no toxoid formed and no vaccine available

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9
Q

Heat stability of exotoxin and endotoxin

A
  1. Exotoxin : destroyed rapidly at 60 C ( except staphylococcal enterotoxin and E.coli heat stable toxin )
  2. Endotoxin : stable at 100 C for 1 hrs
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10
Q

No vaccine available for endotoxin due to :

A

The structure of endotoxin does not contains protein, therefore the immune system can’t produce antibodies against it

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11
Q

The main mechanisms of exotoxins:

A
  1. Inhibition of protein synthesis
  2. Increase fluid secretion
  3. Inhibit phagocytic ability
  4. Inhibit release of neurotransmitter
  5. Lyse cell membrane
  6. Super-antigens causing shock
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12
Q

Which exotoxin inhibit protein synthesis

A
  1. Diphtheria toxin
  2. Exotoxin A
  3. Shiga toxin (ST)
  4. Shiga-like toxin (SLT)
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13
Q

Which bacteria release Exotoxin A?

A
  1. Pseudomonas

2. S.pyogenes

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14
Q

Which bacteria release shiga-like toxin ?

A

EHEC

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15
Q

Mechanism of diphtheria toxin

A

Inhibition of protein synthesis via ADP-ribosylation of EF-2

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16
Q

Mechanism of Exotoxin A of pseudomonas

A

Inhibition of protein synthesis via ADP-ribosylation of EF-2

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17
Q

Mechanism of shiga toxin and shiga-like toxin :

A

Inhibit of protein synthesis via: Inactivate 60s ribosome by removing adenine from rRNA

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18
Q

Which toxin Inactivate 60s ribosome by removing adenine from rRNA ?

A

Shiga toxin and shiga-like toxin

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19
Q

Which toxin inactivate elongation factor-2 (EF-2) ?

A
  1. Diphtheria toxin

2. Exotoxin A

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20
Q

Which toxin may cause pharyngitis with pseudomembranes in throat and severe lymphadenopathy (bull-neck) ?

A

Diphtheria toxin

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21
Q

Which toxin cause GI mucosal damage (dysentery), also enhances cytokinae release, cause hemolytic uremic syndrome ?

A

Shiga toxin and shiga like toxin

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22
Q

Exotoxin that increase-fluid secretion

A
  1. Heat-labile toxin
  2. Heat-stable toxin
  3. Edema toxin
  4. Cholera toxin
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23
Q

Which bacteria release heat-labile toxin and heat-stable toxin

A

ETEC

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24
Q

Which bacteria release edema toxin

A

Bacillus anthraces

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25
Q

Which bacteria release cholera toxin

A

Vibro cholerae

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26
Q

Mechanism of heat-stable toxin

A

Over activation of guanylate cyclase (⬆️ cGMP) lead to decrease the resorption of NaCL and H2O in gut ➡️ watery diarrhea

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27
Q

Mechanism of heat-labile toxin

A

Over-activates adenylate cyclase ( ⬆️cAMP) Lead to increase secretion of Cl/H2O , ➡️ electrolytes disturbance ➡️ secretory diarrhea .

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28
Q

Mechanism of edema toxin

A

Mimics the adenylate catalase enzyme (⬆️ cAMP)

29
Q

Mechanism of cholera toxin

A

Over-activates adenylate cyclase ( ⬆️cAMP) Lead to increase secretion of Cl/H2O , ➡️ electrolytes disturbance ➡️ secretory diarrhea .

30
Q

Cholera toxin. Cause

A

Rice watery diarrhea

31
Q

Over-activation of which enzyme lead to increase cAMP

A

Adenylate cyclase

32
Q

Over-activation of which enzyme lead to increase cGMP

A

Guanylate cyclase

33
Q

Which toxin inhibit phagocytic ability

A

Pertussis toxin

34
Q

Mechanism of pertussis toxin

A

Over activation of adenylate cyclase (⬆️cAMP)

35
Q

Manifestation of pertussis toxin

A

Whooping cough

36
Q

Which disease can cause 100 day cough in adult

A

Whooping cough

37
Q

Toxin inhibit releasing of neurotransmitter

A
  1. Tetanospasmin

2. Botulinum toxin

38
Q

Mechanism of tetanospasmin and botulinum toxin :

A

Both are protease that cleave SNARE, (a set of proteins required for neurotransmitter release via vesicular fusion)

  1. Tetanospasmin: prevent releasing of GABA
  2. Botulinum toxin : prevent releasing of ACH
39
Q

Manifestation of tetanospasmin :

A

Spastic paralysis, lock-jaw

40
Q

Manifestation of botulinum toxin

A

Flaccid paralysis, floppy baby

41
Q

Toxin that lyse cell membrane

A
  1. Alpha toxin

2. Streptolysin-O

42
Q

Alpha toxin mechanism

A

Phospholipase C (lecithinase), that degrades tissue and cell membrane

43
Q

Manifestation of alpha toxin :

A
  1. Myonecrosis
  2. Gasgangrene
  3. Hemolysis
44
Q

Streptolycin-O mechanism

A

Protein that Degrade cell membrane

45
Q

The different betweent alpha toxin and sterptolysin-O

A
  • alpha toxin: phospholipase (lecithinase)

* sterptolysin-O : protein

46
Q

Manifestation of streptolysin-O

A
  1. Lyses of RBC & PMNs

2. Clear zone of hemolysis

47
Q

Streptolysin-O used for diagnosis of which disease

A

Rheumatic fever

48
Q

Toxin that super-antigen causing shock

A
  1. Toxic shock syndrome toxin (TSST-1)

2. Exotoxin A (by s.pyogenes )

49
Q

Mechanism of TSST-1 and exotoxin A ( of s.pyogenes)

A

Bind to MHC-2 and TCR outside of antigen binding site to releasing IL-1, IL-2, IFN-gama, TNF-alpha

50
Q

Manifestations of TSST

A

Toxic shock syndrome :fever , rash , shock

51
Q

Manifestation of Exotoxin A (by s.pyogenes )

A

Toxic shock-like syndrome : fever, rash, shock , scarlet fever

52
Q

Types of shock

A
  1. Septic shock : shock, fever

2. Toxic shock: shock, fever, rash

53
Q

Endotoxin it’s :

54
Q

LPS composed of :

A
  1. O-antigen( oligosacchide) {outer membrane }
  2. Core polysaccharide
  3. Lipid A { Endotoxin }
55
Q

The different between exotoxin and endotoxin (dependent on the mechanism)

A
  1. Exotoxin actively secreted

2. Endotoxin released upon cell lysis or by living cell by blebs detaching from outer surface membrane

56
Q

The main effects of endotoxin

A
  1. Macrophage activation
  2. Complement activation
  3. Tissue factor activation
57
Q

All gram + bacteria don’t have endotoxin except :

58
Q

Activation of macrophage by endotoxin lead to

A

Septic shock

59
Q

Mechanism of septic shock that cause by endotoxin

A

Endotoxin activates macrophage that lead to releasing of:

  1. IL-1,IL6 : fever
  2. TNF-alpha : fever and hypotension
  3. Nitric oxide : hypotension
60
Q

Complement activation by endotoxin lead to :

A

Releasing of

  1. C3a :histamine release -edema + hypotension
  2. C5a: neutrophil chemotaxis
61
Q

Activation of tissue factors by endotoxin lead to

A

Activation of coagulation cascade ➡️ DIC

62
Q

S.aureus toxins

A
  1. TSST-1
  2. Exfoliative toxin
  3. Enterotoxin
63
Q

Enterotoxin of s.aureus cause

A

Rapid-onset food poisoning

64
Q

TSST-1 of S.aureus cause

A

Toxic shock syndrome

65
Q

Exfoliative toxin of s.aureus cause

A

Scalded skin syndrome {SSSS}

66
Q

Diphtheria toxin encoded by

A

B-prophage

67
Q

Cholera toxin similar to which toxin ?

A

Heat-labile toxin of ETEC

68
Q

⬆️ cAMP lead to :

⬆️ cGMP lead to :

A
  1. ⬆️ cAMP lead to : ⬆️ secretion

2. ⬆️ cGMP lead to :⬇️ resorption

Microbiology (13 decks)

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