Tetanus and botulism in the ICU

Also known as Tetanus · Botulism · Tetanospasmin · Botulinum toxin · Human tetanus immune globulin (HTIG) · Heptavalent botulinum antitoxin (HBAT)

Tetanus and botulism are rare but life-threatening toxin-mediated diseases caused by neurotoxins of Clostridium tetani and Clostridium botulinum respectively — two organisms that evolved strikingly opposite toxins from a shared ancestry. TETANUS: C. tetani exotoxin (tetanospasmin) travels by retrograde axonal transport to the spinal cord and brainstem, where it cleaves synaptobrevin (VAMP) and blocks release of the inhibitory neurotransmitters GABA and glycine → unopposed motor-neuron firing → severe muscle spasms (trismus/lockjaw, risus sardonicus, opisthotonus) and life-threatening autonomic instability. Management: HTIG (human tetanus immune globulin) given IM early to neutralise unbound toxin, surgical wound debridement to stop further toxin production, metronidazole IV to eradicate C. tetani (superior to procaine penicillin in direct comparison), titrated benzodiazepines (midazolam) and magnesium sulphate for spasm and autonomic control, ICU admission for airway protection, mechanical ventilation, and cardiovascular support. BOTULISM: C. botulinum toxin (also a synaptobrevin/SNAP-25/syntaxin-cleaving zinc-endopeptidase) blocks acetylcholine release at the neuromuscular junction → symmetric DESCENDING flaccid paralysis beginning with cranial-nerve palsies (diplopia, dysphagia, ptosis, dysarthria) with preserved sensorium and no fever, progressing to respiratory failure. Management: botulinum antitoxin (heptavalent HBAT for adults and children, human BIG-IV for infants), supportive care with NIV or intubation and prolonged ventilation (weeks-to-months), and source removal (wound debridement for wound botulism). Both demand ICU admission, meticulous supportive care, and an understanding of toxin pathophysiology that is heavily examined in the CICM/FFICM/EDIC vivas.

low26 referencesUpdated 26 July 202611 min readSource-verified · Oct 2026

Checked against its sources on 1 Oct 2026

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8 MCQs

The one-line answer

Tetanus and botulism are two clostridial zinc-endopeptidase neurotoxins that share an enzyme but produce opposite syndromes. Tetanus blocks inhibitory neurotransmission centrally — trismus, risus sardonicus, opisthotonus, and the autonomic storm that is the leading cause of death; treat with HTIG given IM early (adult dosing varies 500–10,000 IU; a single 3000 IU IM dose is used in reported adult practice and the 2022 factorial trial), wound debridement, metronidazole, benzodiazepines, and magnesium. Botulism blocks excitatory acetylcholine release peripherally — a symmetric descending flaccid paralysis from the cranial nerves; treat with botulinum antitoxin early (BIG-IV for infants) and prolonged ventilation. Both antitoxins neutralise only circulating toxin — give them early.^[1]^[3]^[16]^[21]

Meet the patient

A 62-year-old undocumented farm worker with no documented vaccinations arrives five days after stepping on a rusty nail, with twenty-four hours of jaw stiffness, back pain, and difficulty swallowing. He is alert but sweaty, with trismus, risus sardonicus, opisthotonus, and a board-like abdomen. A noise triggers a thirty-second generalised spasm with desaturation.^[1]

This is severe generalised tetanus, and the central teaching point is written into the toxin's target: the spasms come from loss of inhibition, not from excess excitation, which is why the treatment restores inhibition (benzodiazepines, magnesium) rather than blocking conduction. A short incubation (under 7 days) predicts a worse prognosis.^[23]

The spine of the topic is the comparison: tetanus blocks the brake, botulism blocks the accelerator. The candidate who can explain why the same enzyme produces spasm in one disease and flaccidity in the other demonstrates mechanism, not rote learning.^[3]

References26Show

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