40 terms

Micro Exotoxins/Endotoxins

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MOA of toxin produced by Corynecbacterium diphtheriae?
Inhibit protein synthesis: Inhibit EF-2
Toxin produced by Pseudomonas?
Exotoxin A
MOA of Toxin produced by Shigella spp.?
Inhibit protein syntesis: Inactivate 60S ribosome by cleaving rRNA
Toxin produced by S. aureus?
1. Enterotoxin 2. Exfoliative toxin 3. Toxic shock syndrome toxin (TSST-1) 4. Alpha toxin 5. Beta toxin 6. Gamma toxin (proteins A, B, C)
Toxin produced by EHEC?
Shigella-like toxin
Toxins produced by ETEC?
1. Heat-labile toxin 2. Heat-stable toxin
Toxin produced by Yersinia enterocolitica
Heat-stable toxin
Toxin produced by Bacillus anthracis
1. Edema factor 2. Lethal factor 3. Protective Ag
MOA of toxin produced by Vibrio cholerae
Overactivates adenylate cyclase by permanently activating Gs -> Inc. cAMP -> Inc. Cl secretion & H20 efflux
MOA of toxin produced by Bordetella pertussis
Overactivates adenylate cyclase by disabling Gi (ADP-ribosylated) -> Inhibit phagocytic activity
MOA of toxin produced by Clostridium tetani?
Cleaves SNARE protein: Inhibit release of inhibitory neurotransmitters (GABA & Glycine) in spinal cord -> Muscle rigidity & "Lock jaw"
MOA of toxin produced by Clostridium botulinum?
Cleaves SNARE protein: Inhibit release of excitatory neurotransmitter (Ach) -> Flaccid paralysis
MOA of toxin produced by pseudomonas?
Inhibit protein synthesis: Inhibit EF-2
MOA of toxin produced by EHEC?
Inhibit protein synthesis: Inactivate 60S ribosome by cleaving rRNA
MOA of heat-labile toxins?
Inc. fluid secretion: Overactivates adenylate cyclase -> Inc. cAMP -> Inc. Cl secretion & H2O efflux
MOA of heat-stable toxins?
Inc. fluid secretion: Overactivates guanylate cyclase -> Inc. cGMP -> Dec. reabsorption of NaCl & H2O in the gut
MOA of edema factor?
Inc. fluid secretion: Mimics adenylate cyclase
MOA of AB toxins?
1. B (binding) component binds to host cell surface receptor, enabling endocytosis 2. A (Active) component attaches ADP-ribosyl to disrupt host cell proteins
Examples of AB toxins?
1. Diphtheria toxin (Inhibit EF-2) 2. Exotoxin A (Inhibit EF-2) 3. Heat-labile toxin (Overactivates adenylate cyclae) 4. Heat-stable toxin (Overactivates guanylate cyclase) 5. Cholera toxin (Overactivates adenylate cyclase - Gs) 6. Pertussin toxin (Overactivates adenylate cyclase - Gi)
Which 5 bacterial toxins are encoded in a lysogenic phage?
ABCDE:
ShigA-like toxin, Botulinum toxin, Cholera, Diphtheria toxin, Erythrogenic toxin of Strep. pyogenes
Toxin produced by Clostridium perfringens?
Alpha toxin
MOA of toxin produced by Clostridium perfringens?
Phospholipase that degrades tissue, cell membranes
Toxins produced by Streptopyogenes?
1. Streptolysin O (oxygen labile) (ASO titers)
2. Streptolysin S (oxygen stable)
3.Exotoxin A (SPE-A & C)
MOA of streptolysin O?
Phospholipase that degrades tissue, cell membranes
MOA of exotoxin A produced by streoptococcus pyogenes?
Bring MHC II & TCR in proximity to cause overwhelming release of IFN-r & IL-2 -> Shock
MOA of alpha toxin produced by S. aureus?
Pore-forming cytolysin
MOA of TSST-1
Bring MHC II & TCR in proximity to cause overwhelming release of IFN-r & IL-2 -> Shock
Exotoxin produced by Listeria?
Listeriolysin O
MOA of exotoxin produced by Listeria?
Pore-forming in phagosome: rapid egress from phagosome
MOA of endotoxin (esp. lipid A)
1. Activates macrophages
2. Activates complement (alternate pathway)
3. Activates Hageman factor
True or False: endotoxin is heat stable
True
Which cytokines are activated by endotoxin (lipid A) to activate macrophages?
1. IL-1 (Fever)
2. TNF (Fever, hemorrhagic tissue necrosis)
3. Nitric Oxide (Hypotension - shock)
Which cytokines are activated by endotoxin (lipid A) to activate complements?
1. C3a (hypotension, edema)
2. C5a (neutrophil chemotaxis)
What does Hageman factor activate?
Coagulation cascade -> DIC
Staph toxins causing hemolysis?
Alpha toxin
Hemolysin (Proteins A + B of Gamma toxin)
Staph toxin: destroys leukocytes?
Leukocidin (Proteins B+C of Gamma-toxin)
Staph toxin: a sphingomyelinase
Beta toxin
Staph toxin: what is Gamma-toxin made up of?
Proteins A, B, C:
A+B=hemolysin ->hemolysis
B+C=leukocidin ->destroys leukocytes
Staph toxin: cause food poisoning -> vomiting and diarrhea
Enterotoxins A-E
Staph toxin: causes epithelial cell lysis -> scalded skin syndrome
Epidermolytic/exfoliative toxin