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13 Cards in this Set
- Front
- Back
What is the etiologic agent of Tetanus? Morphology?
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Clostridium tetani; obligate anaerobic, gram pos spore-forming rods
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What are the characteristics of the tetanus and botulism exotoxins?
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potent; toxin activity is specific for target and Rc sites in CNS; toxins are polypeptides; toxins may be denatured by heating; toxins can be altered to toxoids for vaccine use
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How is infection with C tetani acquired?
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local wound infection
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What is the name of the neurotoxin released by C tetani? How does it work?
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*Tetanospasmin: cleaves *vesicle-associated membrane protein (VAMP/synaptobrevin) in the synaptic vesicles of neurons --> this blocks the release of inhibitory NTs glycine and GABA (inhibits the inhibitor)
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What are the two forms of tetanus (named by their progression in the body)?
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ascending (reaches the CNS via *retrograde axonal transport- limb stiffness followed by CNS infection) and descending (enters bloodstream resulting in cranial nerves affected first followed by body and limbs) tetanus
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In what spp is tetanus most commonly seen?
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horses > ruminants > swine (cats and dogs relatively resistant
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What are the clinical signs of tetanus?
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stiffness, sawhorse stance, risus sardonicus, lock jaw, erect ears, prolapse of third eyelid; spasms may be precipitated by external stimuli such as sudden movement or noise
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How is tetanus diagnosed?
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*clinical signs and history (incubation period is 1-2wks); serum (test for toxin by mouse inoculation); wound (C tetani in necrotic tissue)
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What is the characteristic appearance of C tetani rods?
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"tennis racket" or "drumstick"-shaped endospores
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What is the treatment for tetanus?
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tetanus antitoxin (to neutralize unbound toxin); wound cleansing and debridement; penicillin; tetanus toxoid (can be given with antitoxin); provide dark, quiet environment; sedation as needed; good supportive care
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How is tetanus prevented?
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1. good hygeine in tetanus-associated procedures: castration, tail-dockings, dehornings, etc; 2. tetanus toxoid (routinely given in horses); 3. antitoxin: given to unvaccinated animals with tetanus-prone wounds - give toxoid at same time but at diff injection site
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What dz has been associated with tetanus antitoxin in horses?
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hepatic dz (serum hepatitis/Theiler's dz)
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Is tetanus zoonotic?
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no; humans are very susceptible to tetanus but they do not obtain dz from animals
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