Question.

Which one of the following statements regarding tetanus is correct?

a.Clostridium tetani

    1. is a gram negative organism

b.

    1. The period from inoculation to symptoms is 48 hours

c.Tetanospasmin blocks acetylcholine receptors at neuromuscular junctions

d.Human anti-tetanus immunoglobulin (HATI) is used to treat established disease

e.death occurs by overwhelming sepsis

 

Answer.

The answer is d. Human anti-tetanus immunoglobulin (HATI) is used to treat tetanus

 
Explanation.

Tetanus is caused by the anaerobic gram positive spore forming rod Clostridium tetani. The organism and its spores are ubiquitous in the soil and in the faeces of grass eating animals. Spores germinate and the organism multiplies when inoculated into soft tissues wounds. Particularly favoured by C. tetani are deep or puncture wounds (anaerobic environment), wounds with devitalised tissue and those contaminated with soil or manure. Other at risk groups include: 1) intravenous drug users, where dirty needles are used for drug injection; and 2) neonates where unhygienic practice is used cutting the umbilical cord. The incubation period for tetanus averages eight days (but can be as long as weeks).
The disease, tetanus, typically progresses as follows,
• Tetanus infected wounds initially display marked local soft tissue inflammation.
• systemic features develop with the release of tetanospasmin, a highly potent neurotoxin which blocks the release of the inhibitory neurotransmitter GABA from nerve endings. In the absence of GABA inhibition, muscular spasm and rigidity occur – initially of the muscles close to the infected wound, then of the jaw (causing trismus or lockjaw) and progressing to all muscles to give opisthotonus (whole body rigidity and hyperextension).
• autonomic disturbance – profuse sweating, tachycardia and raised blood-pressure – accompany systemic disease.
• death is by respiratory failure due to respiratory muscle tetany.

Mainstay of treatment for tetanus is wound debridement to remove tissue contaminated with C. Tetani along with neutralization of unbound toxin with anti-tetanus immune globulin (HATI). Most patients will need ventilation on an intensive care unit. Antibiotics (penicillin and metronidazole) are commonly used but have only a minor role. Despite aggressive treatment around 30% of systemically affected cases die.
Prevention of tetanus is through active and passive immunization (see the UK Government’s Green Book: www.gov.uk/government/collections/immunisation-against-infectious-disease-the-green-book. Chapter 30).

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