Clostridium tetani
Tetanus is a serious illness caused by tetanus bacteria. The bacteria live in soil, saliva, dust and manure. The bacteria usually enter the body through a deep cut, like those you might get from cutting yourself with a knife or stepping on a nail.
The infection causes painful tightening of the muscles, usually all over the body. It can lead to "locking" of the jaw, which makes it impossible to open your mouth or swallow. If this happens, you could die of suffocation.
Spores widely distributed in soil and in the intestines and feces of many animals, including dogs and cats. Found also in contaminated heroin; quinine used to dilute the heroin supports the growth of C. tetani.
Scientific classification Kingdom: Bacteria Phylum: Firmicutes Class: Clostridia Order: Clostridiales Family: Clostridiaceae Genus: Clostridium Species: C. tetani Binomial name Clostridium tetani
Morphology C. tetani is a rod-shaped, obligate anaerobe which stains Gram positive in fresh cultures; established cultures may stain Gram negative. During vegetative growth, the organism cannot survive in the presence of oxygen, is heat-sensitive and exhibits flagellar motility. As the bacterium matures, it develops a terminal spore, which gives the organism its characteristic appearance.
Pathogenesis Most cases arises from small puncture wounds or lacerations. The infection remains localised to the site of entry. Access of tetanus spores to open wounds does not necessarily result in disease, especially in clean wounds where the oxygen supply is good and germination is inhibited. In necrotic or infected wounds, anaerobic conditions will permit germination. The incubation period ranges from several days to many weeks. The usual form of the disease is characterised by sever painful spasms and rigidity of voluntary muscles. Spasms of the pharyngeal muscles causes dysphagia and death may result from paralysis of respiratory muscles.
Clostridium tetani - biochemical reactions
Diagnosis, treatment and prevention The diagnosis of tetanus is usually based on clinical findings alone. However, attempts should be made to culture C. tetani from all suspicious lesions. The organism can only be cultured from infective focus in 30% of cases. Antitoxin should be promptly administered in all cases of suspected tetanus. It is ineffective when the toxin is already fixed in the CNS. Tetanus immune globulin (TIG) prepared from persons who have been hyperimmunised with tetanus toxoid has supplanted conventional equine antitoxin.
Careful debridement of the lesion and removal of foreign bodies should be carried out after TIG had been given. Penicillin should also be administered to prevent the germination of spores and further bacterial multiplication. Intensive supportive measures should be given.
Because spores of C. tetani are so widely distributed, the only effective way to control tetanus is by prophylactic immunisation. Tetanus toxoid is usually given as part of DPT. Whenever a previously immunised individual sustains a potentially dangerous wound, a booster dose of toxoid should be given. Nonimmunised individuals should be given TIG.
Medications The preferred medication for treatment of tetanus, according to Johns Hopkins, is 7. 5 mg/kg metronidazole given intravenously over six hours. Alternatively, penicillin, erythromycin, tetracycline, chloramphenicol or clindamycin can be used. In cases where the toxin produced by the infection has not yet interacted with body tissues, tetanus immune globulin (TIG) can be used to neutralize the infection. Vaccination against tetanus is the most common form of prevention.
Tetanus toxoid exists as a structural component of the tetanus bacterium cell membrane, and is also known as an endotoxin, or lipopolysaccharide