Tetanus

From Ganfyd

A very old-fashioned disease which still kills large numbers of people in other countries and a few in the West.

Recent injury (can be quite superfical) + Painful evolving muscle spasm Tight jaw Admit and escalate Respiratory compromise and autonomic dysfunction are later but will happen soon

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^[1].

Prevention

The UK programme for immunisation was started in 1938 for men in the armed services. It was later introduced for the general population in selected areas in the 1950s, but the universal national programme did not start until 1961. This means that middle-aged and older patients may not have received primary immunisation against the toxoid.

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.

Risk

The classic wound is a nail through the boot in a farmyard, but even clean wounds may kill the unimmunised. Take care with the very old with skin ulceration - have they had a tetanus booster

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.

Management

Detailed guidance on the management of a tetanus-prone wound is provided in the chapter 30 of the Green Book.

Treatment

Wound Care

Tetanus-prone wounds should be cleaned, and, if necessary, debrided.

Preventing Effects of Toxin

In the absence of prior immunisation, administration of anti-tetanus serum. This is a form of passive immunity, where antibodies produced by other humans are administered to neutralise the toxoid.

• 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®).

There is an inconsistency in the Green Book recommendations on routine tetanus boosters and treatment of wounds.^[2]

Management of Tetanus

Admit. Paralysis and ventilation may be required.

External Links

• http://textbookofbacteriology.net/clostridia.html

References