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Exotoxins - Overview
- - are proteins released from G -/+
- - Neurotoxins
- - Enterotoxins
- - Pyrogenic Exotoxins
- - Tissue invasive exotoxins
- - Miscellaneous Exotoxins
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Neurotoxins - Function - Organism - Mechanism - Result - Note
- Function:
- - act on nerves or motor end plates causing paralysis
- A. Clostridium tetani
- - Tetanus Toxins
- - H - subunit: binds to neuronal gangliosides
- - L - subunit:blocks release of inhibitory NT
- *Tetanus: continous motor neuron activity/ uncontrolled muscle contraction
- * Vaccine: formalin
- B. Clostridium Botulinum
- - Botulinum Toxin
- - inhibits acetylcholine release from motor end plates
- *Botulism: Flaccid paralysis of resp. m.
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Enterotoxins - Definition - Symptomps - example bacs - Mechanism
- Definiton: act on GIT causing diarrhea
- - inhibit NaCl resorbtion, activate NaCl secretion or kill int. ep. cells
- --> Result: osm. pull of fluid into intestine
- 1) Infectious Diarrhea:
- - Bacs colonize and bind to GOT - cont. releasing enterotoxins
- (patient can die by dehydration if bacs arent killed).
- - eg: E.coli, Vibrio Cholera(cholera = increased cAMP increase intraluminal NaCl & change osmotic pressure), Campylobacter jejuni, Shigella dysenteriae
- 2) Food Poisining:
- - bacs grow in food and release enterotoxins in food
- - person digests this food and vomits or diarrhea in less than 24 h
- - examples: Bacillus cereus and Staph. aureus
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Pyrogenic Exotoxins - definition - examples - mechanism
- Definition:
- stimulates the release of cytokines and can cause:
- a) Strep. pyogenes: Scarlet fever/ rush
- b) Staphyl. aureus: Toxic shock syndrome (Fever,rash)
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Tissue Invasive exotosin - Defintion - Examples - Symptomps
- Function:
- - allows bac to destroy and tunnel through tissue
- - includes enzymes that destroy DNA, collagen, NAD, RBC & WBC
- Examples:
- a) Strept. pyrogenes: Hemolysins, DNAase, Hyalurinadase (s. Q50)
- b) Staphylo. aureus (s. Q54): lipase, penecillinase, Leukocidin
- --> hydrolyzes lipids, activates plasminogen, lyses WBC
- c) Clostridium perfringens
Symptomps: Skin infections, Abscesses, Systemic infection
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Miscellaneous Exotoxins - Definition- examples - Symptomps
- Definition:
- - a virulance factor
- a) Bacillus antracis: edema factor - stops phagocytosis by increasing the cAMP to deactivate Macrophage (s. Q80)
- b) Corynebacterium diptheriae: myocarditis, Peripheral nerve palsies (Q. 62)
- c) Berdetella pertussis (Q 59): whooping cough
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