Clostridium tetani - Tetanus

Diagnosis

Indications for Testing

  • Muscle spasms, trismus, and dysphagia, especially in setting of obvious wound

Criteria for Diagnosis

Laboratory Testing

  • Initial testing
    • CBC with differential
    • Cerebrospinal fluid analysis – to rule out other causes of encephalitis/meningitis
    • Gram stain
    • Wound culture
  • Difficult to confirm diagnosis based on testing – must use clinical judgment for therapy decisions
  • Vaccination status and immunodeficiency
    • Paired IgG titers from samples taken prior to and 1 month after vaccination may be used if antibody deficiency suspected
    • Do not use to diagnose tetanus

Differential Diagnosis

Clinical Background

Tetanus is a central nervous system disease resulting from neurotoxin produced by Clostridium tetani.

Epidemiology

  • Incidence – 0.03/100,000 in the U.S.
    • Most common in developing countries – as many as 28/100,000
  • Age
    • >50 years, often in rural areas
    • Unvaccinated or incompletely vaccinated infants
  • Transmission
    • Post-injury (50%)
    • Drug abuse or animal-related injuries (25%)
    • Wounds of unknown cause (20%)
    • No known source (5%)

Organism

  • Slender, gram-positive, sporulating, anaerobic bacillus
    • Spores can survive in soil for years

Risk Factors

  • Extremes of age
  • Residence in developing country
  • Lack of vaccination
  • Immunocompromised condition

Pathophysiology

  • Tetanus toxin (tetanospasmin) binds to nerve endings and prevents release of neurotransmitters
  • Spores usually enter through penetrating wound
  • Toxin may affect neurons for 4-6 weeks

Clinical Presentation

  • 3-14 days incubation
  • Generalized disease (most common form)
    • Initial complaints – difficulty swallowing, neck stiffness, pain
    • Tonic contractions of skeletal muscles and intermittent intense muscle spasm – opisthotonus, stiff neck, risus sardonicus, trismus, apnea, dysphagia
    • Fractures of vertebrae not uncommon
    • Symptoms of overreactivity – irritability, restlessness, sweating, tachycardia
    • Complications – rhabdomyolysis with renal failure; sudden cardiac arrest
  • Localized disease
    • Partial immunity allows localized effect of toxin at wound site; often precedes generalized tetanus
    • Prolonged, steady, painful contraction in wound region
  • Cephalic disease
    • Involves cranial nerves (CN), if organism has entered wound in head or neck region
      • CN VII most common
    • Focal neuropathies
    • May develop into full-blown, generalized form of disease
  • Neonatal disease
    • Usually associated with inappropriate birth practices in developing countries (eg, mud applied to umbilical stump)
    • Most cases occur within first 14 days after birth
    • Spasms, trismus, rigidity, seizures, inability to suckle
    • High mortality

Treatment

  • Supportive
  • Sedation and muscle relaxants
  • Ventilator support
  • Passive and active immunization
  • Local wound care
  • Consider antibiotics

Prevention

  • Vaccination

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Assess for presence of infection

   
Meningoencephalitis Panel with Reflex to Herpes Simplex Virus Types 1 and 2 Glycoprotein G-Specific Antibodies, IgG, CSF 2008917
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Chemiluminescent Immunoassay

Rule out other viral and bacterial etiologies of meningitis/encephalitis

   
Wound Culture and Gram Stain 0060132
Method: Stain/Culture/Identification

Confirm C. tetani as organism of disease

Negative culture does not rule out disease

Isolates may be non-toxigenic

 
Tetanus Antibody, IgG 0050535
Method: Quantitative Multiplex Bead Assay

Determine IgG antibodies in response to vaccination

For tetanus antibody titer, order with diphtheria and tetanus antibodies, IgG

Do not use to diagnose tetanus

Requires comparison of samples taken prior to and 1 month after vaccination

If concentrations of IgG, IgM, and IgA are low, low-normal or even normal, and antibody deficiency still strongly suspected, determine IgG subclass and response to protein antigens such as diphtheria, tetanus toxoid, and H. influenzae, as well as to pure polysaccharide antigens such as unconjugated pneumococcal vaccine

Diphtheria, Tetanus, and H. Influenzae b Antibodies, IgG 0050779
Method: Quantitative Multiplex Bead Assay

Determine IgG antibody titers in response to vaccination

Determine IgG antibody titers to tetanus and diphtheria toxoids and H. influenzae PRP simultaneously

Requires comparison of samples taken prior to and 1 month after vaccination

If concentrations of IgG, IgM, and IgA are low, low-normal or even normal, and antibody deficiency still strongly suspected, determine IgG subclass and response to protein antigens such as diphtheria, tetanus toxoid, and H. influenzae as well as to pure polysaccharide antigens such as unconjugated pneumococcal vaccine

Additional Tests Available
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Strychnine 0091574
Method: Quantitative Gas Chromatography
Strychnine, Quantitative, Urine 0091075
Method: Quantitative Gas Chromatography
Diphtheria & Tetanus Antibodies, IgG 0050595
Method: Quantitative Multiplex Bead Assay

For diphtheria antibody titer, order with diphtheria antibody, IgG to:

  • Determine patient's response to protein toxoid (majority of antibody falls within IgG/subclass 1)
  • Diagnose antibody deficiency in patients with recurrent infections, especially sinopulmonary and gastrointestinal

For tetanus antibody titer, order with tetanus antibody, IgG to:

  • Determine whether vaccine recipient responded to vaccine with protective levels of antibodies
  • Determine IgG antibody titers to tetanus and diphtheria toxoids and H. influenzae PRP simultaneously

If concentrations of IgG, IgM, and IgA are low, low-normal or even normal, and antibody deficiency still strongly suspected, determine IgG subclass and response to protein antigens such as diphtheria, tetanus toxoid, and Haemophilus influenzae as well as to pure polysaccharide antigens such as unconjugated pneumococcal vaccine