Clostridium Tetani

• Gram positive Bacillus
• Non capsulated
• Sporing
• Obligatory anaerobe
• Drum stick appearance/tennis racket appearance
• Spherical & terminal spores
• Motile by peritrichate flagella except type IV which is non motile.
• Tetanus spores are highly resistant to:
  • boiling and autoclaving for 15 minutes at 120 ( Heat) 

CULTURAL CHARACTERSTICS:         

`Filde’s technique’:

• Shows swarming growth over the surface of agar. 
• This property enables the sepration of Cl. tetani from mixed cultures

Incubation period of clostridium tetani:

• 6-10 days
• Robertson’s cooked meat broth.
• Grows well
• Shows Swarming growth.

On blood agar:

• alpha-hemolysis is produced
• Which later develops into 13-hemolysis, due to the production of hemolysin (tetanolysin)

Produces 2 toxins –

1.  Tetanolysin (hemolysin)
2. Tetanospasmin(neurotoxin)

Tetanotysin (hemolysin) :

• no role in pathogenesis
• oxygen labile hemolysin

Tetanospasmin:

• Oxygen stable
• Plasma coded
• Single chain zinc-metalloprotease
• Release in wound with low redox potential, revitalised tissue
• Cleave into heavy chain and light chain
• Light chain active moiety
• Binds to motor neuron
• Enters axon
• transported to nerve cell body
• Blocks cleavage of synaptobrevin
• Block release of inhibitory neurotransmitters glycine and GABA of spinal cord
• Acting pre-synaptically → abolition of spinal inhibition → spread of uncontrolled impulses initiated elsewhere in the CNS