AKT · Infections/Tropical, zoonotic & travellow yield

Tetanus

Clostridium tetani toxin (tetanospasmin) from a contaminated wound → unopposed muscle spasm

Overview

A potentially fatal disease caused by the neurotoxin (tetanospasmin) of Clostridium tetani, which enters through a contaminated (especially deep/dirty/devitalised) wound and blocks inhibitory neurotransmission, causing severe muscle spasm and autonomic instability. It is now rare in vaccinated populations, so the high-yield exam content is wound-based prophylaxis (by wound type and immunisation status) rather than treatment of established disease.

Recognise

Established disease: TRISMUS (lockjaw), RISUS SARDONICUS (fixed grimace), generalised muscle spasms, OPISTHOTONUS (arched back), dysphagia, autonomic instability (labile BP/HR); spasms triggered by stimuli
Incubation days–weeks after a tetanus-prone wound (deep puncture, soil/manure contamination, devitalised tissue, burns, IVDU)
A clinical diagnosis; the priority in practice is PREVENTION via wound management

Red flags

Established tetanus (spasms, laryngeal/respiratory involvement, autonomic storm) → ICU emergency
A tetanus-prone wound in an unimmunised/uncertain patient → tetanus immunoglobulin + vaccine

Differentials & how to tell them apart

Dystonic reaction (drug-induced)acute dystonia from antipsychotics/metoclopramide — responds to procyclidine; history of the drug

Strychnine poisoning / hypocalcaemic tetanydifferent toxin/biochemistry

Meningitis/encephalitisneck stiffness from meningism vs trismus/spasm of tetanus

Investigations

Clinical diagnosis (no test should delay treatment); assess the WOUND (tetanus-prone?) and the patient's IMMUNISATION status to decide prophylaxis.

Management

Wound-based prophylaxis (vaccine ± immunoglobulin by wound type/immunisation); established disease → ICU + IG + metronidazole

1In practice the key skill is PROPHYLAXIS: assess whether the wound is tetanus-prone (deep, dirty, devitalised, soil-contaminated) and the patient's immunisation status. Fully immunised + clean minor wound → none; tetanus-prone or uncertain immunisation → tetanus vaccine ± tetanus immunoglobulin, with thorough wound cleaning.Gate: Established tetanus (trismus, risus sardonicus, spasms, autonomic instability) is an ICU emergency → tetanus immunoglobulin + metronidazole + debridement + spasm/autonomic control.
2Manage established disease in ICU (benzodiazepines, ventilation, autonomic support); ensure routine vaccination for prevention.

Prophylaxis by WOUND TYPE + IMMUNISATION STATUS — fully immunised + clean minor wound → none; tetanus-prone wound or uncertain/incomplete immunisation → tetanus vaccine ± tetanus IMMUNOGLOBULIN; thorough wound cleaning/debridement always

Established disease: tetanus immunoglobulin + metronidazole + wound debridement — neutralise toxin, kill organism, remove the source

Control spasms + autonomic instability (ICU) — benzodiazepines, muscle relaxation/ventilation, manage autonomic storm

Vaccination (prevention) — the routine immunisation schedule; the disease is vaccine-preventable

Key points

Clostridium tetani toxin from a contaminated wound → trismus (lockjaw), risus sardonicus, opisthotonus, spasms, autonomic instability. Now rare if vaccinated, so the exam tests WOUND PROPHYLAXIS: decide by wound type (tetanus-prone?) + immunisation status → vaccine ± tetanus immunoglobulin + wound cleaning. Established disease → ICU + IG + metronidazole.

Monitor & prognosis

Spasm/autonomic control and respiratory status (established disease); ensure prophylaxis given for at-risk wounds.

Vaccine-preventable; established tetanus has significant mortality despite ICU care.

Source: UKHSA / Green Book tetanus; cross-ref MSK (wounds), child_health (immunisation)