• Clinical science

Tetanus (Lockjaw)

Summary

Tetanus (lockjaw) is an acute disease caused by neurotoxins from the bacterium Clostridium tetani. C. tetani is ubiquitous in spore form and enters the body through broken skin (e.g., deep puncture wounds). Its toxins then cause uncontrolled activation of alpha motoneurons, leading to muscular rigidity and spasms. Patients classically present with a triad of trismus, risus sardonicus, and opisthotonus. Despite treatment with anti-tetanus toxoid immunoglobulin and antibiotics (e.g., metronidazole), the overall prognosis is poor once symptoms begin. Therefore, vaccination as primary prevention is crucial.

Etiology

  • Pathogen
  • Route of infection
    • Clostridial spores contaminate a wound (e.g., through dirt, saliva, feces)
    • Localized ischemia, necrosis, foreign bodies and/or coinfection with other bacteria predispose to infection
    • Wounds with compromised blood supply create anaerobic conditions that are required for the germination and multiplication of C. tetani.
  • Groups with a higher risk: non-immunized individuals; , those with diabetes, neonates, IV drug abusers, certain patient groups (i.e., postsurgical, obstetric, dental) [1]

Pathophysiology

Ubiquitous C. tetani spores contaminate a wound → bacteria reproduce under anaerobic conditions → production of neurotoxins tetanospasmin and tetanolysin

Neurotoxins cause tetanus (not the pathogen itself)!

Clinical features

  • Incubation period: 3–21 days (average: ∼ 10 days)
  • Generalized tetanus: painful muscle spasms and rigidity
    • Trismus: lockjaw due to spasms of the jaw musculature
      • Commonly the first tetanus-specific sign
    • Risus sardonicus; : grinning caused by cramps of the facial muscles
    • Neck stiffness
    • Opisthotonus: backward arching of spine, neck, and head caused by spasms of the back muscles
    • Abdominal rigidity
    • Life-threatening complications
      • Laryngospasm and/or respiratory muscles spasms → respiratory failure [5]
      • Autonomic dysfunction → circulatory arrest and shock [5]

Subtypes and variants

Neonatal tetanus

  • Occurs in infants of inadequately immunized mothers after unsterile management of the umbilical stump
  • Typically occurs 5–8 days after birth, but incubation period can be up to a several weeks
  • Typically a rapid onset of symptoms as axonal length in infants is shorter than in adults [6]
  • Symptoms include:

Other types

  • Localized tetanus: Patients present with painful muscle contractions in areas surrounding injury site only.
  • Cephalic tetanus

Diagnostics

  • Tetanus is a clinical diagnosis based upon muscle spasms and rigidity associated with an entry point for bacteria and inadequate immunization.[7]
  • Wound culture and serology may confirm the diagnosis but have low sensitivity and specificity

Treatment

In addition to initial supportive care, management should focus on controlling the infection, eliminating toxin production, and neutralizing circulating toxins.

Prevention

Tetanus vaccination [8]

Since recovery from infection does not confer immunity following recovery, routine immunization is generally recommended!

Tetanus prophylaxis after injury

Vaccination history Clean, minor wounds All other wounds

Unknown or < 3 tetanus toxoid doses

Active immunization with tetanus toxoid (Td or Tdap) Active immunization with Td or Tdap AND passive immunization with HTIG
≥ 3 tetanus toxoid doses

Active immunization with Td or Tdap if last vaccination ≥ 10 years ago

Active immunization if last vaccination ≥ 5 years ago