How does Clostridium tetani make you ill and what do you die of?

Answer 1

Clostridium tetani is a member of the large family of bacteria called "Clostridiae". These bacteria are small strictly anaerobic gram-positive rods, responsible for several unrelated diseases with various manifestations including botulism, tetanus and gas gangrene.

Specifically clostridium tetani causes tetanus - a very severe disease, which luckily can be prevented through proper immunization. Most often c. tetani is contracted through traumatic wounds. The way in which c. tetani causes damage is through the production of toxins, specifically the major toxin know as tetanospasmin.

This toxin attaches to the nerves in the region of the wound, where it is transmitted to cranial nerve nuclei. It inhibits normal inhibitory input, thereby causing increased resting tone of muscles and characteristic reflex spasms (ie. patellar reflex increased).

From this stage of increased muscle tone the disease progresses to a stage where trismus (locked jaw) is observed. The locked jaw is caused by involuntary contractions in the jaw-musculature. From here the disease descends, initially involving neck and back muscles, which flex in spasms, but later on producing a board like rigidity of the abdominal musculature. Eventually the muscles of the extremities are also contracted in spasms leading to a generalized spasm that is characterized by a tonic seizuer where the legs are fully extended, the arms are firmly flexed and held tightly next to the body and arching of the back and neck. Death usually results from respiratory failure caused by paralysis of respiratory muscles.

See link for a classic painting of a british soldier wounded in 1809 in the Napoleonic Wars.

textbookofbacteriology.net/themicrobialworld/SoldierTetanus.gif