Essay on Tetanus!
Meaning of Tetanus:
Tetanus caused by CI. tetani, occurs in man and animals. When a wound is infected with CI. tetani under conditions that allow the organism to multiply and produce the toxin, absorption of the toxin leads to hyper-excitability of voluntary musculature.
The disease is characterised by increased muscle tonus and exaggerated muscular response to simple stimuli. Trismus occurs as early sign of tetanus in man, when jaw muscles are affected and the disease is called as “lock jaw“.
CI. tetani are Gram-positive rod-shaped bacilli. They are motile with numerous peritrichous flagella. Their spores are spherical, terminal, larger than the diameter of the bacillus producing a typical “drumstick” appearance.
CI. tetani are obligate anaerobes, grow best at 37°C in cooked meat medium. The spores may be highly resistant to adverse conditions. They resist dry heat at 150°C for 1 hour. 5% phenol, Iodine in watery solution and hydrogen peroxide (10 volumes) kill them within a few hours.
Tetanus toxin: It is an exotoxin and has two components:
(a) Neurotoxic constituent (tetanospasmin) is the essential pathogenic constituent and has been separated as pure crystalline protein which can kill mouse in dose of 0.0000001 mg. It is an extremely powerful toxin, second in potency only to the exotoxin of CI. Botulinum.
Tetanolysin is another constituent which causes lysis of red blood cells. It is oxygen labile.
Tetanus antitoxin is often called antitoxin serum (ATS) — can be obtained by immunizing horse with toxoid. This serum is of great value in the prophylaxis of tetanus, when given immediately after wounding. Its use as a curative agent after the development of tetanus is less effective.
At the international conference of Tetanus, Mumbai, it was decided that an initial dose of 10,000 units of antitoxin should be adopted in the treatment of adult cases of Tetanus.
When intravenous antitoxin is prescribed it should be proceeded by a subcutaneous test dose, followed by an intramuscular test dose at half hour interval. The antitoxin should be diluted, warmed at room temperature and injected slowly into the recumbent patient.
Precautions while Injecting Antitoxin:
Routine precautions should be taken before an antitoxin is administered to avoid the risk of anaphylactic reaction following injection of antitoxin. Information’s regarding previous serum injections, any history of asthma, infantile eczema, urticaria and other allergic condition should be obtained from the patient.
In the absence of contraindication, the full doses of antitoxin may be injected, but a sterile syringe and needle with adrenaline (1ml of 1: 1000) solution should be ready. The patient should be kept warm before and after treatment and he should be under observation for at least 30 minutes after the injection.
If the patient has had a previous injection of serum, but gives no history of an allergy, a subcutaneous test dose of 0.2 ml antitoxin shall be given and full dose of antitoxin may be given if no general reactions have occurred after 30 minutes.
If the patient gives a history of allergy, the initial test dose should be 0.2 ml of a 1: 10 dil of antitoxin subcutaneously. If no general symptoms develop within 30 minutes, this may be followed by 0.2 ml of undiluted antitoxin subcutaneously. The full dose may be given if there are no general reactions after a further dose.
The toxin can be detoxified by the chemical (formaldehyde). During the conversion period the toxin part is destroyed leaving antigenic part intact. Thus the toxoid is an excellent immunizing agent.
A course of three 0.5 ml doses of tetanus toxoid (formol toxoid) with intervals of 6 to 12 weeks between the first two doses and 6 to 12 months between the second and third injection is proved valuable in the prevention of tetanus. A reinforcing (booster) dose of 0.5 ml toxoid should be given at intervals of 5 to 10 years to maintain immunity.
Tetanus is usually the result of contamination of a wound with CI. tetani spores from the soil. Deep punctured wounds, wounds associated with devitalized, necrotic tissue and wounds contaminated with soil, ionised calcium salts and silicic acid favour the germination of spores of CI. tetani and multiplication of this organism and production of the toxin.
This tetanus toxin is absorbed by the motor nerve endings and spread up the space between the nerve fibres. It seems to act as excitant to the motor cells in the anterior horn of the spinal cord and may diffuse in the CNS. It may also interfere with the normal inhibition of motor impulses, thus producing early increase in tonus and tonic spasms of muscles and also impairs the release of acetylcholine.
Laboratory diagnosis can be done by microscopic examination of Gram-stained films of wound exudate for typical ‘drumstick’ appearance bacilli. They grow in Robertson cooked meat medium or anaerobically in blood agar medium.
A course of systemic penicillin or tetracycline therapy should be given in cases of established tetanus and, at the same time, antibiotics should be applied in and around wound.
Application to Nursing:
Nurse should invariably disinfect and dispose off all dressings soiled with the wound exudate. She should take all precautions while administrating antiserum to avoid the anaphylactic shock. She should wear gloves while dressing wound and should not delay in treating wound.