Clostridium tetani is a Gram-positive, rod shaped bacteria. Under gram staining, the bacterium takes on the appearance of small drumsticks or tennis rackets. The bacteria produces a powerful toxin called tetanospasmin that causes the disease tetanus. Tetanus was recognized throughout history as an illness resulting from open wounds that caused severe muscle spasms and often resulted in death for those who contracted it. The toxin was isolated from soils in 1884 by Arthur Nicolaier.
During this same time period, other scientists demonstrated the infectious nature of the disease by injecting rabbits with the bacteria from deceased human specimens. Later it was discovered that the infection could be combated fairly easily by the use of certain antibodies. This breakthrough was invaluable during World War II, and many lives were saved through the administering of a tetanus fighting vaccine which was developed in 1924. The vaccine is actually an inactive form of the toxin, and rarely results in noticeable side effects. When side effects do occur, they are usually mild and can include fever and pain at the administration site, or more severe side effects such as seizures.
When fully matured, the bacteria are rather resilient to antiseptics and other environmental conditions, however during its developmental stages; it cannot survive in the presence of oxygen and is extremely heat sensitive. Upon maturation each bacterium develops an end spore, giving them the recognizable racket shape. At this stage they are present in most manure, some soil, and even sometimes in impure heroin.
A host organism generally becomes infected by Clostridium tetani when the bacteria enters through an open wound. Rapid replication and toxin release then begins; the toxins quickly spread through the circulatory system and eventually bind to the ends of nerve cells. The toxins bind to the central nervous system in the brain and spine and, without treatment, will cause involuntary spasms and muscle contractions in the host. Hypertension, or high blood pressure, and tachycardia, or irregular heartbeat, both may in the host organism.
Despite the fact that a vaccine does exist, the toxin tetanospasmin produced by Clostridium tetani is one of the most powerful toxins per weight known to man. This conclusion has been made based on tests to mice, and the estimated minimum lethal dose in humans is 2.5 nanograms per kilogram. The only toxin found to be more lethal in mice is called botulinum toxin, which is the contributing agent in diphtheria.