Toxins
Table Of Contents
Toxins Summary
| Organism | Toxins |
| Bacillus Anthracis | Edema Toxin (Edema Factor) – Mimics AC to increase cAMP – Probably causes edematous borders of black eschar in cutaneous anthrax |
| Bordetella Pertussis | Pertussis Toxin – Overactivates AC to increase cAMP by DISABLING Gi (disabled Gi) – Stops phagocytosis – Causes Whooping Cough |
| Clostridium Botulinum | Botulinum Toxin – Proteases that cleave SNARE (soluble NSF attachment protein receptor) – Flaccid paralysis, floppy baby, prevents the release of excitatory ACh at NMJ – Flaccid paralysis |
| Clostridium Perfringens | Alpha Toxin – Lecithinase that degrades tissue/cell membranes – Gas gangrene – Double zone of hemolysis |
| Clostridium Tetani | Tetanospasmin – Proteases that cleave SNARE (soluble NSF attachment protein receptor) – Spastic paralysis, risus sardonicus, lockjaw, – Can’t release inhibitory GABA/Glycine from Renshaw cells in SC |
| Corynebacterium Diphtheriae | Diphtheria toxin – Inactivates EF-2 (ribosylation) – Causes pharyngitis w/ pseudomembranes and severe LAD (bull’s neck) |
| EHEC | Shiga-like toxin – Inactivate 60S ribosome by removing As from rRNA – Enhance cytokine release causing HUS – Serotype O157:H7 – DOES NOT INVADE HOST CELLS |
| ETEC | Heat-Labile Toxin – Overactivates AC to raise cAMP –> increase Cl-/H2O secretion in the gut Heat-Stable Toxin – Overactivates HC to raise cGMP –> decrease resorption of NaCl and H2O in gut |
| Pseudomonas Aeruginosa | Exotoxin A – Inactivates EF-2 (ribosylation – Causes host cell death |
| Shigella species | Shiga Toxin – Inactivate 60S ribosome by removing As from rRNA – Causes GI mucosal damage –> dysentery – Increases cytokine release –> HUS |
| Staphylococcus Aureus | TSST-1 – Binds to MHC II/TCR outside Ag binding site to cause an overwhelming release of IL-1/2, IFN-Gamma, and TNF-Alpha – TSS – SSS = exfoliative toxin – Food poisoning = pre-formed enterotoxin |
| Streptococcus Pyogenes | Streptolysin O – Protein that degrades cell membrane – Lyses RBCs, Beta-hemolysis, host Abs made, diagnose RF Exotoxin A – Binds to MHC II/TCR outside Ag binding site to cause an overwhelming release of IL-1/2, IFN-Gamma, and TNF-Alpha – Leads to Toxic Shock Syndrome |
| Vibrio Cholerae | Cholera Toxin – Overactivates AC to increase cAMP via Gs – Increased Cl- secretion into the gut and H2O efflux – Massive rice-water diarrhea |
Endotoxin
- LPS found in Gram- outer membranes
- O antigen + Core polysaccharide + Lipid A (toxic component)
- Released upon cell lysis or by blebbing off of living cells (NOT exotoxin)
- Effects:
- – Macrophage activation (TLR4)
- – Complement activation
- – Tissue factor activation
- ENDOTOXINS:
- – Edema
- – NO
- – DIC/Death
- – Outer membrane
- – TNF-Alpha
- – O-Ag + core poly + lipid A
- – eXtremely heat stable
- – IL-1/6
- – Neutrophil chemotaxis
- – Shock
