What Are the Most Common Causes Of Tetanus?

Tetanus is a specific infection of Clostridium tetanus that invades the human body through skin or mucosal wounds, grows and reproduces under hypoxic conditions, and produces toxins that cause muscle spasms. Tetanus toxin mainly affects motor neurons in the nervous system. Therefore, the disease is characterized by closed teeth, paroxysmal spasms, and tonic spasms. The main muscle groups affected include masseter muscles, dorsal spinal muscles, abdominal muscles, Extremities muscles and so on. The incubation period of tetanus is usually 7-8 days, which can be as short as 24 hours or as long as months or years. The shorter the incubation period, the worse the prognosis. About 90% of patients develop symptoms within 2 weeks after injury. Occasionally, patients develop tetanus symptoms after removing foreign bodies that have remained in the body for many years. The population is generally susceptible, and wounds of various types and sizes may be contaminated with soil or sludge containing Clostridium tetanus, but only a few patients will develop the disease. In the warm season with many outdoor activities, injured patients are more common. There is no lasting immunity after illness, so it can be re-infected.

Basic Information

English name: tetanus
Visiting department: General surgery

Common causes: Various types and sizes of wounds can be infected with Clostridium tetanus
Common symptoms: Closed teeth, angled bows, hyperreflexia, etc.

Causes of Tetanus

Tetanus is a specific infection often associated with trauma. Trauma of various types and sizes may be contaminated, especially open fractures, rust-containing wounds, small and deep stab wounds, blind tube trauma, firearm wounds, and are more susceptible to contamination by tetanus. Pediatric patients are more common with stab wounds to their hands and feet. If you apply wounds with soil, incense ash, firewood ash and other soil methods, it is more likely to cause disease.

In addition to various traumas, it can also occur in women and newborns who give birth under unclean conditions, and after informal abortion. Otitis media, pressure ulcers, tooth extraction, and intrauterine ring insertion are all possible causes of the disease. There is also an increase in the number of people who suffer from tetanus due to the use of dirty syringes to inject drugs intravenously.

The pathogenic Clostridium tetanus is an absolute anaerobic bacterium and is positive for Gram staining. Both animal and human faeces can contain bacteria. After being excreted with the faeces, they are distributed in nature in the form of spores, especially in the soil, where they live for several years. This bacterium has a strong resistance to the environment, and is resistant to boiling for 15 to 90 minutes. Clostridium tetanus produces a highly toxic exotoxin, the neurospasm toxin. After the toxin is produced, it does not cause inflammation locally, but spreads to the surroundings, invades the muscle tissue, and passes upward in a direction opposite to the nerve impulse, and finally enters the motor nucleus of the anterior horn of the spinal cord or the brain stem.

Although the pollution rate of wounds and wounds is very high, the pollution rate in battlefields can reach 25% to 80%, but the incidence of tetanus only accounts for 1% to 2% of polluters, suggesting that the disease must have other factors, the main factor is the hypoxic environment . During trauma, Clostridium tetanus can contaminate deep tissues (such as blind tube trauma, deep stab wounds, etc.). If the external mouth of the wound is small, there is necrotic tissue in the wound, the blood clot is stuffed, or the packing is too tight, ischemia, etc., and a hypoxic environment suitable for the growth and reproduction of the bacteria is formed. If there is an aerobic infection, the latter will consume the residual oxygen in the wound, making the disease more prone.

Tetanus clinical manifestations

There is an incubation period between the infection of Clostridium tetanus and the onset of tetanus. The length of the incubation period is related to the location of the wound, the infection and the immune status of the body. It is usually 7-8 days, and can be as short as 24 hours or as long as several months or years. The shorter the incubation period, the worse the prognosis. About 90% of the patients develop symptoms within 2 weeks after the injury. The incubation period of neonatal tetanus is 5 to 7 days after the umbilical cord is broken. Occasionally, patients have tetanus symptoms after removing foreign bodies that have remained in the body for many years.

Forequarter symptoms

Those with slow onset may have symptoms such as general weakness, dizziness, headache, weakness in chewing, local muscle tightening, pain, and hyperreflexia before onset.

2. Typical symptoms

It is mainly manifested by de-inhibition of the motor nervous system, including muscle rigidity and muscle spasm. The muscle groups that are usually affected first are the chewing muscles, followed by facial expression muscles, neck, back, abdomen, limb muscles, and finally the diaphragm muscles. The signs of muscle rigidity are difficulty in opening the mouth and closeness of teeth. The abdominal muscles are as plate-shaped, the neck is rigid, and the head is tilted back. When the back and abdominal muscles contract at the same time, the back muscles are more powerful, and the trunk is twisted into an arch, forming " "Angular bow reversed" or "Side bow reversed." Paroxysmal muscle spasm occurs on the basis of muscle rigidity and persists during periods of spasm. Corresponding signs are frowning, lowering of the corners of the mouth, grinning "bitter smile" (facial muscle spasm); blocked throat, difficulty swallowing, choking (pharyngeal muscle spasm); difficulty in ventilation, cyanosis, respiratory arrest (respiratory and diaphragmatic spasm) ; Urinary retention (spasm of bladder sphincter). Strong muscle spasms can break muscles and even cause fractures. The cause of death was mostly asphyxia, heart failure or pulmonary complications.

The above attacks can be induced by slight stimuli such as light, sound, contact, drinking water, etc., or they can be spontaneous. Mild cases have no more than 3 seizures per day; severe cases have frequent seizures, which can occur once every few minutes, or even persistent. The duration of each attack ranges from seconds to minutes.

The course of the disease is generally 3 to 4 weeks. If the patient is actively treated without special complications, the severity of the attack can be gradually reduced. The remission period is about 1 week on average. However, muscle tension and hyperreflexia can continue for a period of time; some mental symptoms such as hallucinations, speech, and movement disorders can also occur during the recovery period, but they can recover on their own.

3. Autonomic symptoms

It is caused by toxins that affect sympathetic nerves, with obvious fluctuations in blood pressure, faster heart rate with arrhythmia, constriction of peripheral blood vessels, and sweating.

4. Special type

(1) Local tetanus is manifested in the rigidity and spasm of the wound site or facial masseter muscle.

(2) Tetanus of the head and face caused by head trauma, patients with facial, eye movement, and hypoglossal nerve paralysis are paralyzed, while non-paralyzed patients have closed teeth, facial and pharyngeal muscle spasms.

Tetanus check

Tetanus patients generally have no specific findings in laboratory tests. When there is a secondary infection in the lungs, the white blood cell count can be significantly increased, and the corresponding pathogenic bacteria can be found in sputum culture. Aerobic purulent bacteria are often isolated from wound secretions. Clostridium tetanus can be isolated from anaerobic culture of wound secretions in 30% of patients. Due to the clinical manifestations of tetanus, the diagnosis is not difficult when the symptoms are typical, so routine anaerobic culture and bacteria are not required for clinical diagnosis Learn evidence.

Tetanus diagnosis

The symptoms of tetanus are typical, and its diagnosis is mainly based on clinical manifestations and history of trauma. The focus is on early diagnosis, so anyone with a history of trauma, regardless of the size and depth of the wound, should consider the possibility of this disease if muscle tension, tears, difficulty in opening mouth, stiff neck, and hyperreflexia appear after the injury. Negative wound secretion culture does not rule out the disease. For patients suspected of tetanus, passive hemagglutination analysis can be used to determine the level of tetanus antitoxin antibodies in the serum. Tetanus can be ruled out if the antitoxin titer exceeds 0.01U / ml. It should be distinguished from other diseases that cause muscle spasm, such as various purulent meningitis, encephalitis, and tremor of hand and foot.

Tetanus complications

Aspiration pneumonia, atelectasis, pulmonary embolism; various secondary infections; heart failure; gastrointestinal bleeding; spinal compression fractures, etc.

Tetanus treatment

Tetanus is a very serious disease with a high mortality rate, especially for newborns and drug users. To this end, active comprehensive treatment measures must be taken, including removing toxin sources, neutralizing free toxins, controlling and relieving spasms, and keeping the airways open. And prevention of complications. The main treatment measures are:

Wound treatment

All necrotic tissue and foreign bodies in the wound must be removed. After antitoxin treatment, the wound should be treated under good anesthesia and spasm control. Thorough debridement and adequate drainage should be performed. Locally, it can be washed with 3% hydrogen peroxide solution. After debridement The wound does not have to be sutured. Some wounds seem to have healed, and the sinus or dead space should be checked carefully.

2. Application of antitoxin

The purpose is to neutralize free toxins, so it is effective only in the early stages. Toxins have been combined with neural tissues, but it is difficult to obtain results. However, because antitoxin has an allergy rate of up to 5% to 30%, an intradermal allergy test must be performed before medication. Tetanus human immunoglobulin is effective in early application and is usually used only once.

3. Control Spasm

After admission, the patient should live in an isolated ward to avoid light and sound stimulation; avoid harassing the patient and reduce seizures. According to the situation, sedative and antispasmodic drugs can be used alternately to reduce the patient's spasm and pain. The drugs available are: Diazepam (which can block the transmission between neurons and relax the muscles), intramuscular or intravenous drip. Similar drugs include laurazepam and midazolam; chlorpromazine (can inhibit the central Nervous system, reduce muscle spasm), intramuscular or intravenous drip, used alternately with diazepam, but not for low blood volume; phenobarbital (sedative) intramuscularly every 8-12 hours; 10% water Chloroaldehyde (suitable for severe spasms) is taken orally or with an enema. Those with frequent spasms are not easy to control. Slow intravenous injection of thiopental sodium is needed, but be alert to the occurrence of laryngeal spasm and respiratory depression. It is safer for those who have had tracheotomy. However, sedative antispasmodics should be used with caution in neonatal tetanus. Lobelin and colamin can be used as appropriate.

4. Pay attention to prevention and treatment of complications

The main complications are in the respiratory tract, such as suffocation, atelectasis, and lung infections. Therefore, for severe patients with frequent seizures and difficult to control drugs, tracheotomy should be performed as soon as possible to improve ventilation; respiratory secretions should be removed in time and turned over frequently 4. Slap back to prevent fallout pneumonia; patients with tracheotomy should pay attention to airway management, including airway nebulization, humidification, and irrigation. Special care when necessary to prevent accidents; strict aseptic technique to prevent cross infection. For those who have been complicated with pulmonary infection, antibiotics should be selected according to the strain. Indwelling catheter is used to improve urinary retention, and anal canal is used to improve abdominal distension.

5. Nutrition support

Due to the continual spasms and sweating, the patient consumes more calories and loses water every day. So pay great attention to nutrition (high calories, high protein, high vitamins) supplementation and adjustment of water and electrolyte balance. If necessary, central parenteral nutrition can be used.

6. Antibiotic treatment

Antibiotics can be injected intramuscularly with penicillin or intravenously in large doses, which can inhibit Clostridium tetanus. Metronidazole can also be given orally or intravenously in divided doses for 7 to 10 days. If there is mixed infection in the wound, antibacterial drugs should be selected accordingly.

Tetanus prognosis

Tetanus patients have a higher mortality rate, with an average case fatality rate of 20% to 30%, and severe cases as high as 70%. The neonatal and elderly mortality rates are particularly high. Adverse factors affecting prognosis include: acute onset; short incubation period; those who occur on the basis of open fractures, deep puncture wounds, severe burns, gangrene, abortion, etc. The main causes of death were asphyxia, atelectasis, heart failure, and pulmonary embolism.

Tetanus prevention

The current understanding of tetanus is prevention over treatment. Tetanus is preventable, and measures include active immunization with tetanus toxoid injections, proper treatment of wounds, and the use of passive immunization to prevent disease after injury. The main preventive measures are:

Active immunity

Tetanus toxoid is injected as an antigen to make the body produce antibodies to achieve the purpose of immunity. Basic injections with toxoids usually require three injections. 0.5ml is injected subcutaneously for the first time, and then 0.5ml is injected at intervals of 4-8 weeks, and 0.5ml is injected again 6-12 months after the second injection. The three injections are called basic injections, which can obtain relatively stable immunity. Subsequent injection of 0.5 ml of toxoid subcutaneously every 5 to 7 years as a booster injection can maintain sufficient immunity. Immunity is produced within 10 days after the first injection, and an effective protective antibody concentration can be reached after 30 days. The wounded with basic immunity do not need to inject tetanus antitoxin after injury, as long as subcutaneous injection of 0.5ml toxoid can obtain sufficient immunity.

2. Passive immunity

The method is suitable for patients who have not received or completed the full active immunization, and have wound contamination, improper debridement, and severe open injury. Tetanus antiviral serum (TAT) is the most commonly used passive immune preparation, but it can be sensitized by antigenicity. The commonly used dose is 1500U intramuscularly. If the wound is heavily contaminated or injured for more than 12 hours, the dose is doubled and the effective effect is maintained for about 10 days. Allergy tests should be done before injection. TAT intradermal test allergy can be injected by desensitization method.