Tetanus Prophylaxis

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Tetanus: Pathophysiology - Spore Wars

  • Agent: Clostridium tetani (anaerobic); spores in soil, dust, feces.
  • Toxin: Tetanospasmin (neurotoxin).
  • Pathogenesis:
    • Spores enter wound → germinate.
    • Toxin via retrograde axonal transport to CNS.
    • Inhibits glycine & GABA release (Renshaw cells) → disinhibition.
  • Manifestations: Incubation 3-21 days.
    • Trismus (lockjaw), risus sardonicus, opisthotonus.
    • Autonomic dysfunction. Tetanospasmin mode of action

⭐ Tetanospasmin, the neurotoxin from Clostridium tetani, acts by blocking the release of inhibitory neurotransmitters (GABA and glycine) in the central nervous system, leading to unopposed muscle contraction and spasm.

Tetanus: Wound Risk - Danger Zones

Understanding wound type is crucial for appropriate tetanus prophylaxis.

FeatureClean Minor WoundsTetanus-Prone Wounds
Age of Wound<6 hours>6 hours
DepthSuperficial, <1 cm>1 cm
ConfigurationLinearStellate, avulsion, puncture
Tissue ViabilityHealthyDevitalized tissue
ContaminationMinimalSoil, feces, saliva, foreign body, GSW
OtherCrush injuries, burns, frostbite, open fractures, denervated/ischemic tissue, septic abortion

⭐ Wounds older than 6 hours, or those with devitalized tissue, contaminants (soil, feces, saliva), puncture type, crush injury, burns, or frostbite are considered tetanus-prone.

Tetanus: Immunization - Shot Sleuthing

  • Primary Immunization:
    • Childhood: 3 doses (DTP/DT/TT).
    • Adults: 3 doses (Td/Tdap).
  • Booster Doses:
    • Every 10 years.
    • Every 5 years for tetanus-prone wound if last dose >5 years ago.
  • History: Documented vs. unreliable. Serological testing not routine.

⭐ A patient is adequately immunized if they have documented completion of a primary series of at least 3 doses of tetanus toxoid-containing vaccine, with the last dose within 10 years (or 5 years for a tetanus-prone wound).

Tetanus: Prophylaxis Protocol - Guard Up!

Key Agents for Prophylaxis:

  • Active Immunity: Tetanus Toxoid (TT/Td/Tdap) 0.5 mL IM.
  • Passive Immunity: Tetanus Immunoglobulin (TIG).
    • Human (hTIG): 250 IU IM.
    • Equine: 1500-3000 IU IM (after sensitivity test).
  • 📌 Administer TT & TIG at separate sites if both indicated.

Categorize wound: Clean/Minor vs. Tetanus-Prone (e.g., contaminated with dirt/faeces/saliva, devitalized tissue, >6h old, puncture, avulsion, crush, burn, frostbite).

⭐ For a tetanus-prone wound in a patient with unknown or incomplete (<3 doses) vaccination history, both Tetanus Toxoid (e.g., Td 0.5 mL IM) and Tetanus Immunoglobulin (TIG 250 IU IM for human) should be administered at separate sites.

Tetanus: Special Cases - Handle with Care

  • Pregnancy: Tdap preferred, ideally 27-36 weeks (2nd/3rd trimester); Td if Tdap unavailable.

    ⭐ Tdap in each pregnancy (27-36 weeks) gives neonatal passive immunity (tetanus, diphtheria, pertussis).

  • HIV/Immunocompromised: Full primary series + boosters. TIG per guidelines; response may be suboptimal.
  • Incomplete/Unknown History: Treat as unimmunized (<3 doses).
  • Elderly: Standard guidelines; consider immunosenescence.
  • Prior Vaccine Reaction: Assess severity; specialist consultation if severe_

High‑Yield Points - ⚡ Biggest Takeaways

  • Clean minor wounds: If <3 doses or unknown history, give Td. If ≥3 doses, Td only if >10 years since last dose.
  • All other wounds (dirty/major): If <3 doses or unknown, give Td + TIG. If ≥3 doses, Td if >5 years since last dose.
  • TIG (Tetanus Immunoglobulin): Standard prophylactic dose is 250 IU IM.
  • Full primary immunization: Requires three properly spaced doses of tetanus toxoid.
  • Booster doses: Every 10 years routinely; or after 5 years for tetanus-prone wounds in immunized individuals.

Practice Questions: Tetanus Prophylaxis

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