Morphology

• The Gram stain is a common staining technique used to classify bacteria and enhance the appearance of their physical characteristics. When examined under a microscope, Gram-positive bacteria appear purple and Gram-negative bacteria appear red, according to the University of Pennsylvania Health System website. Clostridium tetani is a Gram-positive, rod-shaped, spore-forming bacterium. The round spores located at one end of the bacterium give it its characteristic drumstick appearance.
  
  

Toxin Production

• Clostridium tetani produces a nerve toxin called tetanospasmin. Tetanospasmin blocks the release of specific chemical messengers, called neurotransmitters, that inhibit muscle contractions. The absence of the neurotransmitters causes generalized, sustained muscle spasms.
  
  

Tetanus

• Contracted jaw muscles is one of the first signs of tetanus; this is why tetanus is commonly called lockjaw, according to the Palomar College website. Jaw immobility is followed by progressive rigidity and severe spasticity of the limb and trunk muscles. Tetanus eventually causes respiratory failure and death.
  
  

Infection

• A Clostridium tetani infection is associated with deep puncture wounds, particularly when the injury is caused by a rusty nail or other spore-contaminated object. Deep wounds provide the anaerobic conditions necessary for spore germination and toxin production. Immunization with inactivated tetanus toxin prevents tetanus.