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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
Which bacteria release cholera toxin
Vibro cholerae
26
Mechanism of heat-stable toxin
Over activation of guanylate cyclase (⬆️ cGMP) lead to decrease the resorption of NaCL and H2O in gut ➡️ watery diarrhea
27
Mechanism of heat-labile toxin
Over-activates adenylate cyclase ( ⬆️cAMP) Lead to increase secretion of Cl/H2O , ➡️ electrolytes disturbance ➡️ secretory diarrhea .
28
Mechanism of edema toxin
Mimics the adenylate catalase enzyme (⬆️ cAMP)
29
Mechanism of cholera toxin
Over-activates adenylate cyclase ( ⬆️cAMP) Lead to increase secretion of Cl/H2O , ➡️ electrolytes disturbance ➡️ secretory diarrhea .
30
Cholera toxin. Cause
Rice watery diarrhea
31
Over-activation of which enzyme lead to increase cAMP
Adenylate cyclase
32
Over-activation of which enzyme lead to increase cGMP
Guanylate cyclase
33
Which toxin inhibit phagocytic ability
Pertussis toxin
34
Mechanism of pertussis toxin
Over activation of adenylate cyclase (⬆️cAMP)
35
Manifestation of pertussis toxin
Whooping cough
36
Which disease can cause 100 day cough in adult
Whooping cough
37
Toxin inhibit releasing of neurotransmitter
1. Tetanospasmin | 2. Botulinum toxin
38
Mechanism of tetanospasmin and botulinum toxin :
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
Manifestation of tetanospasmin :
Spastic paralysis, lock-jaw
40
Manifestation of botulinum toxin
Flaccid paralysis, floppy baby
41
Toxin that lyse cell membrane
1. Alpha toxin | 2. Streptolysin-O
42
Alpha toxin mechanism
Phospholipase C (lecithinase), that degrades tissue and cell membrane
43
Manifestation of alpha toxin :
1. Myonecrosis 2. Gasgangrene 3. Hemolysis
44
Streptolycin-O mechanism
Protein that Degrade cell membrane
45
The different betweent alpha toxin and sterptolysin-O
* alpha toxin: phospholipase (lecithinase) | * sterptolysin-O : protein
46
Manifestation of streptolysin-O
1. Lyses of RBC & PMNs | 2. Clear zone of hemolysis
47
Streptolysin-O used for diagnosis of which disease
Rheumatic fever
48
Toxin that super-antigen causing shock
1. Toxic shock syndrome toxin (TSST-1) | 2. Exotoxin A (by s.pyogenes )
49
Mechanism of TSST-1 and exotoxin A ( of s.pyogenes)
Bind to MHC-2 and TCR outside of antigen binding site to releasing IL-1, IL-2, IFN-gama, TNF-alpha
50
Manifestations of TSST
Toxic shock syndrome :fever , rash , shock
51
Manifestation of Exotoxin A (by s.pyogenes )
Toxic shock-like syndrome : fever, rash, shock , scarlet fever
52
Types of shock
1. Septic shock : shock, fever | 2. Toxic shock: shock, fever, rash
53
Endotoxin it’s :
Lipid A
54
LPS composed of :
1. O-antigen( oligosacchide) {outer membrane } 2. Core polysaccharide 3. Lipid A { Endotoxin }
55
The different between exotoxin and endotoxin (dependent on the mechanism)
1. Exotoxin actively secreted | 2. Endotoxin released upon cell lysis or by living cell by blebs detaching from outer surface membrane
56
The main effects of endotoxin
1. Macrophage activation 2. Complement activation 3. Tissue factor activation
57
All gram + bacteria don’t have endotoxin except :
Listeria
58
Activation of macrophage by endotoxin lead to
Septic shock
59
Mechanism of septic shock that cause by endotoxin
Endotoxin activates macrophage that lead to releasing of: 1. IL-1,IL6 : fever 2. TNF-alpha : fever and hypotension 3. Nitric oxide : hypotension
60
Complement activation by endotoxin lead to :
Releasing of 1. C3a :histamine release -edema + hypotension 2. C5a: neutrophil chemotaxis
61
Activation of tissue factors by endotoxin lead to
Activation of coagulation cascade ➡️ DIC
62
S.aureus toxins
1. TSST-1 2. Exfoliative toxin 3. Enterotoxin
63
Enterotoxin of s.aureus cause
Rapid-onset food poisoning
64
TSST-1 of S.aureus cause
Toxic shock syndrome
65
Exfoliative toxin of s.aureus cause
Scalded skin syndrome {SSSS}
66
Diphtheria toxin encoded by
B-prophage
67
Cholera toxin similar to which toxin ?
Heat-labile toxin of ETEC
68
⬆️ cAMP lead to : | ⬆️ cGMP lead to :
1. ⬆️ cAMP lead to : ⬆️ secretion | 2. ⬆️ cGMP lead to :⬇️ resorption

Microbiology (13 decks)

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