• Clinical science

Tetanus (Lockjaw)

Abstract

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 convulsive 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
    • Clostridium tetani, gram-positive rod, obligate anaerobe, spore-forming
    • Produces neurotoxins
    • Ubiquitous (especially animal feces and soil)
  • Route of infection
    • Clostridial spores contaminate the wound (e.g., through dirt, saliva, feces)
    • Wounds with compromised blood supply create anaerobic conditions that are ideal for the multiplication and germination of C. tetani.
      • Deep, penetrating wounds (e.g., knife, gunshot, animal bites)
      • Open fractures
      • Surgical procedures (e.g., bowel and biliary tract surgery, septic abortion)
      • Burns
      • Umbilical stump infections
      • Often associated with contamination; (dirt, saliva, feces), foreign bodies; , localized ischemia; , necrosis; , and/or coinfection with other bacteria
  • Groups with a higher risk: non-immunized individuals; , diabetics, neonates, 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 toxins tetanospasmin and tetanolysin

Neurotoxins cause tetanus (not the pathogen itself)!

Clinical features

  • Incubation period: 3–4 days (up to several weeks in rare cases)
  • Initial presentation: flu-like symptoms and headache
  • Painful tonic spasms
    • Spasms begin in facial muscles, then progress in a descending pattern
    • Trismus: lockjaw due to tonic spasms of the jaw musculature
      • Commonly the first tetanus-specific sign
    • Risus sardonicus; : grinning caused by tonic cramps of the facial muscles
    • Opisthotonus: lumbar hyperlordosis caused by tonic-clonic spasms of the back muscles
    • Abdominal rigidity
    • Tetanus seizures
  • Life-threatening complications
    • Laryngospasm and/or respiratory muscles spasms → respiratory failure [5]
    • Autonomic dysfunction → circulatory arrest and shock [5]
  • Although generalized tetanus accounts for over 80% of cases, localized and cephalic forms are possible

Subtypes and variants

Neonatal tetanus

  • Occurs in infants of poorly immunized mothers after aseptic management of the umbilical stump
  • Typically occurs 5–8 days after birth, but could be up to a few weeks
  • Typically a rapid onset of symptoms as axonal length in infants is shorter than in adults
  • Symptoms include difficulty opening the mouth and feeding; due to trismus, risus sardonicus, and/or clenched hands

Diagnostics

  • Tetanus is a clinical diagnosis. [6]

Treatment

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

  • Wound cleaning and debridement
  • Antibiotic treatment
  • IM injection of vaccines
    • Denatured tetanus toxoid has an intact receptor binding site and can activate humoral immune response.
    • Human tetanus immunoglobulin (HTIG)
    • Tetanus toxoid-containing vaccine: for example, TdaP, Td, DTaP, DT, DPT, or tetanus toxoid, depending on age or allergies (see “Prevention” below for details) [7]
      • Inject in separate site from HTIG
      • If patient has not received initial immunization before infection: second and third dose 1–2 months and 6–12 months later, respectively
  • Supportive care: transfer to ICU, ventilation, spasmolytics, antiepileptics

Prevention

Tetanus vaccination [8]

  • Tetanus toxoid-containing vaccines according to age groups
    • For children < 7 years of age
    • For adolescents and adults
      • Tdap (tetanus, diphtheria, pertussis): recommended for patients 11–64 years of age, but may be considered for children > 7 years old
      • Td (tetanus, diphtheria): for patients > 11 years old
  • Initial immunization recommendations: children < 7 years of age → 5 doses of DTaP (see “Immunization schedule”):
    • 2 months
    • 4 months
    • 6 months
    • 15–18 months
    • 4–6 years
  • Booster recommendations
    • Children 11–12 years of age: single dose of Tdap[9]
    • Adults 19–64 years of age: single dose of Tdap[9]
    • Adults ≥ 19 years of age: Td (tetanus, diphtheria) every 10 years

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 TIG
≥ 3 tetanus toxoid doses

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

Active immunization if last vaccination ≥ 5 years ago

No tetanus vaccination is necessary in patients with vaccine protection (successful initial immunization and booster vaccinations), regardless of the kind of injury!