Habitat: soil, water, intestines of many animals and humans
Pathogenicity: The bacteria itself is non-invasive and does not cause intestinal disease. However, the spores are excreted with the feces and enter the soil where they are viable. If they enter the dead, oxygen-free tissue of a wound, they germinate to vegetative cells that produce several different toxins. The most important one is an exotoxin (from a plasmid) called tetanospasmin. This neurotoxin blocks the release of inhibitors at the synapse causing continual triggering of muscles, resulting in tetany or "rigid paralysis".
With "localized tetanus", the toxins travel along the peripheral nerves causing a disease confined to the extremities.
Generalized tetanus affects the entire body. Symptoms can develop extremely rapidly -- often within hours. The more peripheral the wound, the longer the incubation time. Patients experience muscle stiffness, "lockjaw", arching of the back, spasmodic inhalation, seizures in the diaphragm and rib muscles, and may eventually lead to death.
Treatment: tetanus toxoid injections are prophylactic and must be given with a booster every 10 years.
If infected: local debridement; sedatives; muscle relaxants; because spasms may be triggered by environmental stimuli (light or the sound of footsteps) patients are placed in quiet, dark rooms; metronidazole is the drug of choice today; human tetanus immunoglobin.
Clostridium tetani
