QUESTIONS

1. What is the name of that Gram-positive, low-down, spore-forming no good, anaerobic rod that produces tetanus neurotoxin.
    
2. How long to the spores of the above no good, low down bacteria last in the environment?
    
3. What is the difference between tetanolepsin & tetanospasmin?
    
4. How long does it take from the time of the wound to the initial neuro signs?
    
5. How the hell do you diagnose tetanus?
    
6. How the hell do you treat tetanus?
   
   
   
   
    

ANSWERS

1. We open with a simple question. Clostridium tetani is the no good low down spore-forming gram positive rod in question.
   
   
   
   
    
2. Spores can survive months or year indoors in the absence of direct sunlight.  They resist autoclave temps of 120 degrees for 15-20 minutes.  Once these low down no good spores reach an anaerobic environment, like a wound, they vegetate/grow & produce toxin.
   
   
   
   
    
3. Tetanolepsin is not considered clinically significant.  It hemolyzes red cells. Tetanospasmin is the neurotoxin.  Note: tetanospasmin does not enter through the GI tract (the toxin gets digested) & it does not cross the placental barrier.  This toxin crawls into the NMJ & climbs up the axon of the motor nerve right up into the spinal cord & brain.  The toxin also spreads to blood & is taken hematogenously to the brain where it then crawls down the cranial motor nerves (they have shorter axons than the spinal motor nerves).  Thus you often see cranial nerve signs first (risus sardonicus, ears straight out, difficulty opening jaws, retracting eye & bringing up 3rd lid).
   
   
   
   
    
4. Typically it takes 5-10 days to see neuro signs but this can be delayed up to 3 weeks in small animals as they seem to be somehow resistent to the toxin.  In dogs, often tetanus signs seem localized to an area near the wound.
   
   
   
   
    
5. Neuro signs w/a recent wound would be what you are looking for. Often the blood panel is inflammatory because of the wound.  Isolation of the organism from the wound is not usually rewarding. Culture must be done under strict anaerobic conditions & takes a long time.
   
   
   
   
    
6. First, you will need to get some anti-toxin. This will neutralize toxin that isn't yet bound to the CNS.  You get the fastest blood levels of anti-toxin by giving it IV over 5-10 min but, of course, you risk anaphylaxis.  You can give an intradermal .1cc to observe for reactions.  Pretreat with steroids & antihistamines if using TAT IV.  A therapeutic blood level will persist for 14 days.
   
   As for drugs to kill the Clostridium, Penicillin is supposed to be drug of choice & ampicillin is supposedly not reliable.  To be honest, flagyl (metronidazole) seems to work the best of all.
   
   Spasm control: somewhat surprisingly, ace & its relatives are recommended.  They seem to work centrally in the brain stem to depress descending excitatory input on LMNs.    If there is seizuring, phenobarb is recommended for seizure control.  Valium & methocarbamol can be used but they have pretty short half lives & are thus less practical.  Narcotics may just  depress respiratory centers further & that would be bad so don't use them.
   
   If the animal is severely affected, keep in an area that is dark & quiet (minimal stimulation) & just support.