Tetanus is caused by the bacterium Clostridium tetani. As an anaerobe, it is more likely to fester in deep closed wounds. This compounded by the fact that tetanus spores are ubiquitous in the environment and are found in dust, soil, animal intestines and human faeces. Inoculation from even apparently clean wounds is possible.
C. tetani produces more than one toxin, but the clinically significant one is tetanospasmin. Once formed at the wound site, it is distributed by vascular and lymphatic channels. The toxin has a particular affinity for the inhibitory motor neurons of the central nervous system. It also has an affinity for other junctions, but not to the same extent as its cousin, botulinum toxin.
Binding and inactivation of the inhibitory neurones is permanent until nerve re-growth occurs. Loss of this inhibition causes a constant stimulation of the muscle (tetany), causing muscular spasm. Shorter nerves are affected first, the face in particular, giving rise to its layman name of 'lock jaw' ie trismus, with opisthotonus and also the pathognomonic feature risus sardonicus. The conditions of tetanus neonatorum and obstetrical tetanus could be used as a marker of inadequate healthcare resources as they are easily preventable.
Immunisation is with tetanus toxoid, made by treating the toxin to neutralise its effect but leaving its antigenic sites able to provoke immunity, and with alum as an adjuvant to produce a larger and lasting response. Immunisation is very effective.
Clostridium tetani as an anaerobe is more likely to fester in deep closed wounds.
In general punctures including rose thorn wounds and the like are more likely to develop tetanus than open wounds, but superficial grazes may be contaminated with spores and surgical wounds are not exempt. Those who are unimmunised or have lost their immunity are at risk
Burns also present a risk.
Detailed guidance on the management of a tetanus-prone wound is provided in the chapter 30 of the Green Book.
Tetanus-prone wounds should be cleaned, and, if necessary, debrided.
Preventing Effects of Toxin
- Tetanus booster if not in date, i.e. no booster in last 10 years, and less than 5 injections during life time.
- In the UK, tetanus toxoid comes as the DTP combination (diphtheria, tetanus and poliomyelitis). Unfortunately, if patients are fully up-to-date for diphtheria and poliomyelitis, there is no single tetanus toxoid injection (use the DTP combination Revaxis®).
Management of Tetanus
Admit. Paralysis and ventilation may be required.