Clostridium tetani was discovered in 1884 by a German physician Arthur Nicolaier. He found that C.tetani causes tetanus when he injecting test animals with garden soil which contain bacteria. Clostridium tetani is an anaerobic bacterium that is found in soil and animal intestinal tracts. C. tetani bacteria are single-celled and do not contain any membrane-bound organelles, such as a nucleus. It is a Gram-positive bacteria as it lacks an outer lipopolysaccharide membrane and possesses only a thick peptidoglycan cell wall.C.tetani is a rod-shaped bacteria and have flagella in vegetative form and drumstick in shape in its spore form. Eleven strains of C.tetani are identified and all of these strains produce an neurotoxin known as tetanospasmin. This toxin is responsible for Tetanus.[1]

As Clostridium tetani bacteria are anaerobic so they derieve nutrition by the process of fermentation. Acetic acid, butyric acid, butanol and acetone are byproducts of the bacterial fermentation. Certain strains of C. tetani produce different enzymes that are used to externally digest organic material in preparation for fermentation. In the anaerobic condition C. tetani is primarily found in soil, manure, and intestinal tracts. [2]

 Clostridium tetani bacteria have two primary life stages, sporular and vegetative. The latter stage is extremely anaerobic and bacteria of this state are unable to survive oxygen exposure where as sporular form is quite hardy and can withstand oxygen and environmental extremes. Clostridium tetani reproduces by an asexual reproduction process known as binary fission. In this process a single bacteria cell after reaching maxium growth stage divides into two smaller identical clone bacteria cells. Due to this process, C. tetani growth is exponential.

C. tetani usually enters a host through a wound to the skin and then it replicates. On entering the host C. tetani produces two exotoxins known as tetanolysin and tetanospasmin. Eleven strains of C. tetani have been identified which only differ in flagellar antigens and their ability to produce tetanospasmin. The genes that produce toxin are encoded on a plasmid which is present in all toxigenic strains.Tetanolysin serves no known function to C. tetani. Tetanospasmin is a neurotoxin and causes tetanus. Tetanus toxin is generated in living bacteria and is released when the bacteria lyses such as during spore germination or during vegetative growth. A minimum amount of spore germination and vegetative cell growth are required for toxin production. Tetanospasmin is a zinc-dependent metalloproteinase which is similar in structure to botulinum toxin but each toxin have different effects. C. tetani [which remain connected with a disulfide bridge. Cleavage of the tetanospasmin toxin into A and B fragments can also be induced artificially with trypsin.If infections of C. tetani left untreated or ineffectively treated then they may result in the commonly fatal tetanus. Tetanus is a potentially deadly nervous system disease. Tetanus causes muscular spasms (tightening of the muscles) that can cause paralysis of the respiratory (breathing) system and lead to death. The disease is also known as lockjaw because there is a a common symptom of tetanus in which the jaw muscles become tight and rigid and a person becomes unable to open his mouth. Sometimes tetanus affects only one part of the body but usually the infection spreads throughout the body until the entire body becomes paralyzed. The incubation period for tetanus is from two to fifty days. The incubation period is the time between infection and the first appearance of symptoms. There are increased chances of death if symptoms occur early. 

DIAGNOSIS: -

The symptoms of tetanus are quite distinctive and a doctor can diagnose the disease simply by observing the patient. Painless spasm of the muscles of the jaw, difficulty in opening the mouth, contraction of the muscles on the forehead and mouth are the characteristic symptoms. Knowing whether or not the patient has had a tetanus vaccination also helps a doctor make their diagnosis. Other signs of being generally irritable, muscle spasms, and poor ability to take in liquids (poor sucking response), Irregular heartbeat, changes in blood pressure

Tetanus can be tested by spatula test. This simple test involves touching the oropharynx with a spatula or tongue blade. This test typically elicits a gag reflex and the patient tries to expel the spatula (which indicates a negative test result). If tetanus is present patients develop a reflex spasm of the masseters and bite the spatula (which indicates a positive test result).

TREATMENT:-

When a tetanus infection becomes established, treatment usually focuses on controlling muscle spasms stopping toxin production, and neutralizing the effects of the toxin. Treatment includes administration of tetanus immune globulin (TIG) which comprises antibodies which inhibit tetanus toxin (also known as tetanus antitoxins) by binding to and removing unbound tetanus toxin from the body. Binding of the toxin to the nerve endings is an irreversible event, and TIG is ineffective at removing bound toxin. Recovery of affected nerves requires the sprouting of a new axon terminal. Large doses of antibiotic drugs (such as metronidazole or intramuscular penicillin G) are also given once tetanus infection is suspected, to halt toxin production. The wound must be cleaned. Dead and infected tissue should be removed by surgical debridement. Metronidazole treatment decreases the number of bacteria but has no effect on the bacterial toxin. Penicillin was once used to treat tetanus, but this treatment is no longer used, owing to a theoretical risk of increased spasms. However, its use is recommended if metronidazole is not available. Passive immunization with human anti-tetanospasmin immunoglobulin or tetanus immune globulin is crucial. If specific anti-tetanospasmin immunoglobulin is not available, then normal human immunoglobulin may be given instead. All tetanus victims should be vaccinated against the disease or offered a booster shot.

Treatment of tetanus is based on whether it is mild or sever tetanus. Mild cases of tetanus can be treated with: Tetanus immune globulin IV or IM ,metronidazole IV for 10 days ,diazepam tetanus vaccination .

PREVENTION:

There are two important ways to prevent tetanus: getting vaccinated against tetanus along with other routine immunizations, or, after an injury that could cause tetanus, receiving a shot (post-exposure tetanus prophylaxis).For kids, tetanus immunization is part of the DTaP (diphtheria, tetanus, and a cellular pertussis) vaccinations. They typically receive a series of four doses of DTaP vaccine before 2 years of age, followed by a booster dose at 4 to 6 years of age. After that, a booster (Tdap) is recommended at 11 to 12 years of age, and then a tetanus and diphtheria booster every 10 years through adulthood. Post-exposure tetanus prophylaxis also involves getting tetanus shots, but after an injury occurs. Shots given will depend on the number of years since the patient's last booster, the total number of tetanus