Clostridium tetani: Toxins, Pathogenesis, Clinical Findings, Diagnosis, Prevention and Treatment, Control.

Question 1

Clostridium tetani - toxins

Answer 1

🌟 Tetanospasmin (neurotoxin):
- Extremely potent; synthesized as a single polypeptide and cleaved into a heavy and light chain.
- Mechanism: Blocks release of inhibitory neurotransmitters (GABA, glycine) by cleaving synaptobrevin (a SNARE protein) → spastic paralysis.
- Produced only under anaerobic conditions.
- Non-invasive: Toxin is responsible for symptoms, not bacterial spread.
- Encoded on a plasmid; similar to botulinum toxin but causes opposite effects.

Question 2

Clostridium tetani - pathogenesis

Answer 2

🔬 Spores enter through a wound (often puncture-type) → germinate under anaerobic conditions → bacteria remain localized but produce tetanospasmin → toxin binds peripheral nerves, travels retrograde to CNS → inhibits inhibitory neurons → muscle rigidity and spasms (spastic paralysis).

Question 3

Clostridium tetani - clinical findings

Answer 3

🧠 Classic Tetanus Signs:
- Trismus (lockjaw)
- Risus sardonicus (sardonic smile)
- Opisthotonos (arched back due to paraspinal muscle spasms)
- Painful, generalized muscle spasms
- No sensory loss or fever
- Consciousness preserved
👶 Neonatal tetanus: Common in developing countries; due to umbilical stump infection.

Question 4

Clostridium tetani - diagnosis

Answer 4

🔎 Clinical diagnosis:
- Based on history (puncture wound, no vaccination) + symptoms
- No reliable lab test; organism rarely isolated
- Culture not necessary for diagnosis

Question 5

Clostridium tetani - prevention and treatment

Answer 5

🛡️ Prevention:
- Tetanus toxoid vaccine (inactivated toxin), part of DTaP
- Booster every 10 years
- Passive immunization with tetanus immune globulin (TIG) for unvaccinated/incompletely vaccinated individuals with high-risk wounds
💊 Treatment:
1. TIG to neutralize unbound toxin
2. Metronidazole (or penicillin) to kill vegetative bacteria
3. Wound debridement
4. Supportive care (sedation, muscle relaxants, ventilation if needed)

Question 6

Clostridium tetani - control

Answer 6

🌍 Public health control:
- Routine childhood immunization
- Boosters for adults
- Education in developing countries to prevent neonatal tetanus
- Proper wound care in trauma cases