Tetanus & Wound-Related Infections

A farmer steps on a rusty nail and says he 'had a tetanus shot years ago.' Whether that means 3 years or 13 years determines your entire intervention.

Tetanus is caused by Clostridium tetani, an anaerobic spore-forming bacterium found in soil, dust, and animal feces. Spores enter through wounds (especially deep puncture wounds, crush injuries, burns, and devitalized tissue) and produce tetanospasmin, a neurotoxin that blocks inhibitory neurotransmitters (GABA and glycine), causing sustained uncontrolled muscle contraction. Clinical presentation: trismus (lockjaw — inability to open the mouth) is often the first sign, followed by risus sardonicus (sustained facial muscle spasm producing a grimace), dysphagia, nuchal rigidity, opisthotonus (severe arching of the back), and generalized spasms triggered by stimuli (noise, light, touch). Death occurs from respiratory failure due to laryngospasm or diaphragm spasm. Incubation: 3–21 days (shorter incubation = more severe disease). Prevention: DTaP for children (5-dose series at 2, 4, 6, 15–18 months, and 4–6 years), Tdap for adolescents (age 11–12) and adults (once, then Td every 10 years), Tdap in every pregnancy at 27–36 weeks. Wound prophylaxis algorithm: for clean minor wounds, give Td/Tdap if last booster was >10 years ago. For contaminated, deep, or puncture wounds, give Td/Tdap if last booster was >5 years ago. Add tetanus immune globulin (TIG) for contaminated wounds in patients with fewer than 3 prior vaccine doses or unknown history. TIG provides passive immunity — inject at a site separate from the vaccine. Treatment of active tetanus: TIG (neutralizes unbound toxin), wound debridement, metronidazole (kills the organism), benzodiazepines for muscle spasm control (diazepam or midazolam), and mechanical ventilation if needed. Nursing: dark, quiet room with minimal stimulation (stimuli trigger spasms), continuous monitoring with airway management as priority, seizure precautions, and nutritional support (dysphagia limits oral intake). Gas gangrene (Clostridium perfringens): rapidly progressive wound infection with crepitus (gas in tissues — palpable crackling), severe pain, foul-smelling drainage, and tissue necrosis. Requires emergent surgical debridement and IV antibiotics.

Key Distinctions

The wound prophylaxis decision tree is the most tested nursing point: clean wound = booster if >10 years, dirty wound = booster if >5 years, add TIG if <3 doses or unknown. Students confuse Td (tetanus-diphtheria, for routine boosters) with Tdap (includes acellular pertussis, required once in adulthood and every pregnancy). TIG and vaccine are administered at DIFFERENT sites — never mix them in the same syringe or injection site. Risus sardonicus is tetanus, not a seizure — the patient is conscious during spasms. Do not confuse tetanus (wound-acquired, causes painful spasms and rigidity) with botulism (causes descending flaccid paralysis and may be foodborne, infant, or wound-associated).

Clinical Pearl

Dirty wound, >5 years since booster — give the shot. Clean wound, >10 years. That's the whole algorithm for 90% of ED tetanus decisions.