Tetanus is an acute disease caused by the production of a neurotoxin, tetanospasmin, by a bacterium, Clostridium tetani, when the spores of the organism enter a wound, and develop into the toxin-producing vegetative form. The case-fatality rate averages 50 percent in adults and is higher in neonates (especially those in developing nations) and in patients over 60 years of age.

Etiology and Epidemiology

C. tetani is an obligate anerobe, a spore-forming, gram-positive motile rod. The terminal spore caused the organism to be called the “drumstick” rod. The protein toxin, tetanospasmin, blocks acetylcholine release at the motor end-plates. The toxin travels up the nerve trunks, as well as fixing directly on nerve cells. The spinal cord is the primary target organ, with chromatolysis of the motor neurons and inhibition inhibition of antagonists accounting for the spasm and rigidity that characterize the disease. Toxin fixation to central nervous system neurons may lead to seizures; involvement of the sympathetic nervous system may evoke vascular irregularities.

Humans may be considered accidental interveners in the life cycle of the organism, which is a soil saprophyte and a harmless inhabitant of the intestines of many herbivores. The organism requires a wound to invade mammals. Traumatic, surgical, dental, umbilical, burn, and cosmetic wounds are the most common causes of infection in humans. “Skin popping” of addictive drugs, insect bites, and nonmedical abortions are less common causes of infection. As an obligate anaerobe, the organism can reproduce and produce toxin only when local oxidation-reduction processes reduce tissue oxygen to near zero; deep, infected wounds are thus ideal culture media.