Background
- Ubiquitous soil organism
- Acquired either by direct inoculation or via umbilical stump in neonates
Microbiology
- Thin Gram-positive bacillus, with terminal spore (drumstick appearance), with numerous spores
Pathophysiology
- The toxin, tetanospasmin, is a zinc-dependent matrix metalloproteinase that blocks inhibitory interneurons in the spinal cord and autonomic nervous system
Epidemiology
- Rare in developed countries (0.1 to 0.2 cases per million people in the US)
- Cases and deaths have decreased substantially after introduction of vaccination
Clinical Manifestations
- Incubation period of 3 to 21 days, which is followed by a period of onset to the first generalized spasm
- Shorter incubation period and period of onset are both associated with poorer prognosis
Generalized Tetanus
- Disease is characterized by tonic spasms
- Classically starts with muscles of the jaw, causing trismus, lockjaw, and risus sardonicus, and sometimes abdominal rigidity
- Progresses to generalized spasm, which involves decorticate posturing with opisthotonus, arm flexion, and leg extension
- Spasms may be triggered by sensory stimuli
- May cause airway obstruction, and may involve diaphragm, both of which can be fatal
- Disease progresses over two weeks, with complete recovery taking another month
Localized Tetanus
- Rigidity of muscles near the site of inoculation
- May be mild and often resolves spontaneously over time
- May progress to generalized tetanus
Cephalic Tetanus
- Localized tetanus involving the cranial nerves following a head injury
Neonatal Tetanus
- Caused by infection of the umbilical stump, due to contamination in the context of unimmunized mothers
- Presents with generalized weakness and failure to nurse, followed eventually by rigidity and spasms
- Very high mortality (90%)
Prognosis and Complications
- 30% mortality
- Can cause bony fractures, asphyxia, hematomas, and rhabdomyolysis
Diagnosis
- Almost entirely a clinical diagnosis, due to low yield of organism and toxin from clinical samples
- Baseline IgG serology; if positive, then they are tetanus-immune and it rules out the diagnosis
- Send wound swab or tissue for culture or PCR
Management
- Supportive care
- Early intubation for airway protection
- Benzodiazepines to manage muscle spasms
- Rarely, need to escalate to neuromuscular blockage
- May need α- or β-adrenergic blockade with labetalol to manage autonomic dysfunction
- Avoid unopposed α effect, which can cause severe hypertension
- Increased nutritional support, given the high metabolic demands of the illness
- Immunization
- Tetanus antitoxin, tetanus immune globulin (TIg), or IVIg can shorten the duration of illness. Administer as early as possible and within 24 hours.
- Vaccination with toxoid vaccine, within 24 hours, into a different limb.
- Metronidazole may improve outcomes compared to penicillin
- Wound care with debridement as indicated, though it does not alter the course of the disease
Prevention
Vaccination
- The tetanus toxoid vaccine is part of the routine childhood immunization
Postexposure Prophylaxis
- Postexposure prophylaxis involves either tetanus vaccination, tetanus immunoglobulin (TIg), or both
| Immunization Status | Wound | Vaccine | Immunoglobulin |
|---|---|---|---|
| did not complete childhood series,
or unknown |
clean, minor injury | yes | no |
| all others | yes | yes | |
| completed childhood series | clean, minor injury | only if last was given ≥10 years ago | no |
| all others | only if last was given ≥5 years ago | no |
