Tetanus

Basics

Description

  • Tetanus is characterized by muscle rigidity and spasms due to production of a neurotoxin in infected wounds by Clostridium tetani, an anaerobic spore-forming gram-positive bacillus.
  • There are four clinical forms of tetanus: generalized, neonatal, localized, and cephalic.

Epidemiology

  • Tetanus is rare in the United States, with an average of 29 reported cases per year. Nearly all cases are in unvaccinated individuals.
    • Rare cases have been reported in patients with protective levels of antitetanus antibodies.
  • Tetanus continues to occur in countries in which mothers are not immunized and nonsterile care of the umbilical cord is practiced. Worldwide, it is estimated that >250,000 deaths from neonatal tetanus occurred between 2000 and 2003.
  • Generalized tetanus is the most common form of disease.

Risk Factors

  • Inadequate immunization
  • Neonate born to unimmunized mother
  • Elderly with declining immune status
  • Injection drug use
  • Chronic wounds
  • Acute traumatic injury
  • Foreign bodies
  • Nonsterile delivery conditions and practice of applying mud or feces to umbilical cord

General Prevention

  • All wounds should be cleaned with soap and water and foreign bodies should be removed.
  • Universal immunization with tetanus toxoid (For details and information on catch-up schedules, refer to Centers for Disease Control and Prevention (CDC) Web site.)
  • Tetanus postexposure prophylaxis should be initiated at the time of injury:
    • For clean minor wounds:
      • If patient has had ≥3 prior doses of tetanus toxoid (DTaP, Tdap, or Td) and it has been <10 years since the last dose, no prophylaxis is indicated; if it has been ≥10 years since last dose, give tetanus toxoid.
      • If patient has had <3 prior doses of tetanus toxoids, give tetanus toxoid.
    • For all other wounds:
      • If patient has had ≥3 prior doses of tetanus toxoid and it has been <5 years since the last dose, no prophylaxis is indicated; if it has been ≥5 years since the last dose, give tetanus toxoid.
      • Patients with <3 prior doses of tetanus toxoid should receive tetanus immune globulin (TIG) and tetanus toxoid at separate sites.
      • Patients with HIV or severe immunodeficiency should receive TIG regardless of prior immunization history.
    • In neonates or infants <6 months of age who have not received 3 doses of DTaP, the decision to use TIG should be based on mother’s tetanus immunization status; if unknown or inadequate, should give TIG
    • Type of tetanus toxoid to use for prophylaxis:
      • For children <7 years old, use DTaP; if pertussis vaccine is contraindicated, use DT.
      • For a child 7 to 10 years old, use Tdap.
      • For an adolescent 11 to 18 years old who has not received Tdap, use Tdap; for those who have received Tdap or for those whom pertussis is contraindicated, use Td.
    • TIG dose is 250 U IM for wound prophylaxis (regardless of age or weight); if TIG is unavailable, use IV immunoglobulin (IVIG) or tetanus antitoxin (TAT).
      • Because TAT is equine in origin, test patient for sensitivity prior to use.
      • TAT is no longer available in the United States.

Pathophysiology

  • C. tetani produces tetanospasmin, a powerful metalloprotease neurotoxin.
  • Tetanospasmin can be absorbed directly into skeletal muscles adjacent to the injury.
  • Tetanospasmin can travel to the CNS via retrograde axonal transport through peripheral nerves or via lymphocytes.
    • In the CNS, tetanospasmin prevents the release of γ-aminobutyric acid (GABA) and glycine in inhibitory nerve terminals, resulting in sustained excitatory discharges (motor spasms and increased muscle tone) and autonomic instability; tetanospasmin does not directly affect cognitive processes.
    • In the peripheral nervous system, tetanospasmin may block inhibitory impulses to motor neurons.
    • Loss of regulation of adrenal catecholamine release precipitates tachycardia, hypertension, and sweating.
  • Infection does not confer immunity; all patients need to be immunized during recovery.

Etiology

  • Tetanus is caused by C. tetani, a spore-forming, anaerobic gram-positive bacillus.
  • C. tetani is found in soil, animal and human feces, house dust, and salt and fresh water.
  • Under anaerobic conditions, spores become vegetative and produce tetanospasmin; anaerobic conditions in wounds are promoted by extensive necrosis, foreign bodies, or other suppurative infections.

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