Makindo Medical Notes

Related Subjects: |Pasteurella Multocida |Capnocytophaga canimorsus |Snake Bites |Dog Bites |Tetanus |Clostridium perfringens |Clostridioides difficile Infection |Clostridium botulinum Infection

When tetanus spores are exposed to a favorable environment, such as water and nutrients, the bacterium Clostridium tetani can become active, multiplying and releasing toxins that pose a serious health threat.

About

• Clostridium tetani is a bacterium found commonly in soil, dust, and animal waste.
• Causes tetanospasmin toxin release, leading to spastic paralysis, often fatal without intervention.
• A higher risk in areas with inadequate immunization programs and poor wound care.
• Unlike most bacterial infections, tetanus does not provide immunity after recovery; all patients require active immunization.
• Fatality rate: Between 20-60% due to respiratory and autonomic complications.

Microscopy

Characteristics

• Gram-positive, motile, obligate anaerobe found in soil.
• Spore-forming, with a characteristic "drumstick" appearance.
• Produces two neurotoxins: tetanospasmin and tetanolysin.

Aetiology

• Transmission: Spores enter the body through puncture wounds, deep lacerations, surgical incisions, or burns, thriving in low-oxygen environments where they germinate and release toxins.
• Tetanospasmin toxin: A potent neurotoxin that disrupts neurotransmitter release, leading to unregulated muscle contractions.
• Pathophysiology: The toxin enters the presynaptic terminals of lower motor neurons, travels retrogradely to the spinal cord and brainstem, blocking GABA and glycine, which leads to muscle spasms.
• Incubation period: Approximately two weeks; symptoms usually last four to six weeks.

Clinical Presentation

Patients may present with an infected wound and characteristic muscular symptoms:

• Muscle rigidity starting with trismus (lockjaw) and facial muscle spasms, progressing to generalized muscle stiffness.
• Spasms and contractures: Characteristic "sardonic smile" (risus sardonicus), generalized muscle spasms, opisthotonus, and respiratory muscle involvement, which can compromise breathing.
• Autonomic symptoms: Tachycardia, high blood pressure, fever, sweating, and salivation.
• Infection sources: Puncture wounds, surgeries, animal bites, burns, and for neonates, contamination of the umbilical stump.
• Forms of tetanus: Generalized, local, cephalic, and neonatal.

Grading of Tetanus Severity

• I (Mild): Trismus and generalized stiffness without respiratory compromise or spasms.
• II (Moderate): Marked rigidity, brief spasms, mild respiratory distress, and dysphagia.
• III & IV (Severe): Frequent, prolonged spasms, severe respiratory distress, and cardiovascular instability.

Differential Diagnosis

• Strychnine poisoning: Glycine antagonist; test strychnine levels if suspected.
• Acute dystonia: Can present with trismus; exclude with benztropine response.

Investigations

• Blood Agar Culture: Growth without discrete colonies.
• Toxin Detection: Confirm presence of circulating tetanus toxin.

Sensitivity

• Benzylpenicillin: Typically effective against Clostridium tetani.

Prevention

• Vaccination: Active immunization with tetanus toxoid vaccine in routine schedules; booster doses for high-risk injuries.
• Prophylactic Immunoglobulin: Administer 250 units IM for minor contaminated wounds or 3000-6000 units for active cases.
• Wound Care: Prompt and thorough wound cleaning and debridement can reduce infection risk.

Tetanus Toxoid Vaccination

• Booster Requirement: Administer booster doses to maintain immunity.
• Response to Injury: Boosters are essential after high-risk wounds, especially if last immunization was more than 5-10 years ago.

Management

• ABC Support: Airway management may require tracheotomy; neuromuscular blockade may be necessary for severe cases.
• Sedation: Administer oral or IV benzodiazepines for seizure and spasm control; ventilatory support in severe cases.
• Antitoxin Administration:
  • Human Tetanus Immunoglobulin (TIG) 150 U/kg IM across multiple sites.
  • Equine Tetanus Immune Globulin 500-1000 U/kg IM (risk of anaphylaxis).
• Wound Management: Immediate wound scrubbing and debridement post TIG administration; Metronidazole IV for infection control. A trial by Ahmadsyah and Salim demonstrated a mortality benefit for patients treated with metronidazole compared to penicillin as far back as 1985.
• VTE Prophylaxis: Prevents complications in immobilized patients.

Complications

• Autonomic Dysfunction: Instability with sympathetic overdrive, causing hypertension, tachycardia, and respiratory issues; often requires intensive care support. The sedative effect of morphine reduces anxiety and cardiovascular instability.
• Hypotension/Hypertension: Managed with IV labetalol or inotropes as needed.