Tetanus
- Definition
Tetanus is a neuroparalytic disease caused by Clostridium tetani, characterized by painful muscle spasms, rigidity, and autonomic dysfunction. It occurs due to the action of a potent neurotoxin, tetanospasmin.
- Etiology & Microbiology
- Causative agent: Clostridium tetani
- → Anaerobic, Gram-positive, spore-forming bacillus
- → Spores are ubiquitous in soil, animal feces, and rusty metal
- Spores enter the body via:
- Puncture wounds
- Contaminated cuts
- Burns
- Postpartum wounds (neonatal tetanus)
- Intramuscular injections (in drug users)
- Pathogenesis
- Spores germinate in necrotic, anaerobic tissue (low oxygen tension)
- Bacteria produce tetanospasmin (a heat-labile neurotoxin)
- Toxin enters motor neurons → travels retrograde via axons into CNS
- Blocks inhibitory neurotransmitters:
- GABA and glycine (mainly in spinal cord and brainstem)
- Result → uncontrolled excitatory impulses to muscles → rigidity and spasms
The toxin is irreversible once bound. Recovery depends on new axonal terminals forming.
- Forms of Tetanus
- Clinical Features
- Incubation: 3–21 days (shorter = more severe)
- Initial signs:
- Trismus (lockjaw)
- Stiffness in neck and jaw
- Dysphagia
- Progression:
- Generalized muscle spasms
Triggered by light, noise, touch
Painful, intense, may involve respiratory muscles
- Opisthotonus – backward arching of body
- Risus sardonicus – sardonic grin due to facial muscle spasm
- Autonomic dysfunction: labile BP, tachycardia, sweating, arrhythmias
- Patient remains fully conscious
Diagnosis
Clinical diagnosis – based on symptoms and history of wound
No specific lab test; cultures are often negative
Differential diagnosis includes:
- Strychnine poisoning
- Hypocalcemic tetany
- Seizure disorders
Treatment
- Neutralize circulating toxin
Tetanus Immunoglobulin (TIG) – 500 IU IM, given ASAP
Do not inject at the same site as vaccine
- Control infection
Metronidazole IV (preferred) or Penicillin G
Wound debridement to remove necrotic tissue and prevent further toxin release
- Control spasms
Diazepam – for muscle relaxation
Alternatives: baclofen, magnesium sulfate
Muscle relaxants and even neuromuscular blockade if severe
- Supportive care
ICU admission with minimal stimulation
Mechanical ventilation if respiratory compromise
Manage autonomic instability: beta- blockers, morphine, magnesium
- Immunization
Begin/continue full tetanus vaccination schedule
Tetanus vaccine does not give immunity after infection (toxin is too small to induce response)
Prevention
Proper wound cleaning and debridement in all injuries
Tetanus vaccination:
- Primary series (DPT in childhood)
- Booster every 10 years (Td or Tdap)
Post- exposure prophylaxis: