Review Question - QID 101481

The patient described above was infected with Clostridium tetani when he was injured by the floor nail. Typical symptoms of C. tetani infection include lockjaw, opisthotonos, and pronounced reflexes as a result of impaired inhibitory GABA function.

In the wound, C. tetani produces a neurotoxin called tetanospasmin which travels to the spinal cord retrogradely through motor axons. Here, the toxin prevents the fusion of GABA/glycine-loaded vesicles with the cell membrane, thus preventing the release of inhibitory neurotransmitters and disinhibiting motor neurons. This results in tetanus and many of the symptoms seen.

Halaas states that tetanus vaccination is essential in patients with no documentation of vaccination or in whom vaccination was performed greater than 10 years ago. If the wound is visibly dirty, the physician may also be advised to add tetanus immunoglobulin to the regimen in addition to the toxoid immunization.

Campbell et al. state that the anaerobic environment within necrotic tissue is the preferred site for the bacteria to grow, replicate, and secrete the tetanus neurotoxin.

Illustration A shows a man suffering from end-stage tetanus infection with a facial and spinal contractions.

Incorrect Answers:
Answer 1: Impaired motor neuron release of ACh is consistent with a C. botulinum infection (botulism toxin).
Answer 3: Gas gangrene is consistent with a C. perfringens infection (lecithinase).
Answer 4: Antibodies against S. pyogenes are cross-reactive with self antigens in rheumatic fever.
Answer 5: Infiltration of the CNS is prominent in meningitis and would be more consistent with a S. pneumoniae or N. meningitidis.