Clostridium tetani (anaerobic)

Question 1

Disease

Answer 1

tetanus

Question 2

Transmission

Answer 2

• Spores in soil.
• Portal of entry wound site (nail penetrates foot) or skin-popping (drug addicts inject drugs into skin).
• Germination of spores favored by necrotic tissue
  & poor blood supply in wound.
• Neonatal tetanus (enters through contaminated umbilicus or circumcision wound).

Question 3

Pathogenesis: Tetanus toxin (tetanospasmin)

Answer 3

• polypeptide exotoxin from vegetative cells at wound site-> carried intra-axonally (retrograde) to CNS -> binds to ganglioside receptors & blocks
  release of inhibitory mediators (glycine &
  γ-aminobutyric acid [GABA]) at spinal synapses).
• protease that cleaves proteins involved in mediator release from neurons.
• has one antigenic type
• only one antigenic type of tetanus toxoid in vaccine against tetanus.

Question 4

Clinical Findings

Answer 4

• strong muscle spasms (spastic paralysis, tetany)
• lockjaw (trismus) due to rigid contraction of jaw muscles->prevents mouth from opening, risus sardonicus & exaggerated
  reflexes.
• Opisthotonos= pronounced back arching
  -> spasm of strong extensor muscles of back.
• Respiratory failure ensues.
• high mortality rate

Question 5

Laboratory Diagnosis

Answer 5

• no microbiologic or serologic diagnosis.
• Organisms rarely isolated from wound site.
• produces terminal spore (spore at end of rod) gives tennis racket appearance.

Question 6

Treatment

Answer 6

Tetanus immune globulin (tetanus antitoxin) ->
neutralize toxin.

antibiotics-> metronidazole or penicillin G.

Adequate airway maintained & given
respiratory support.

Benzodiazepines (diazepam [Valium]) given to prevent spasms.

Question 7

Prevention

Answer 7

• immunization with tetanus toxoid
  (formaldehyde-treated toxin) in childhood & every 10 years thereafter.
• given to children in combination with diphtheria toxoid & acellular pertussis
  vaccine (DTaP).
• Trauma occurs-> wound cleaned & debrided-> tetanus toxoid booster
• Wound grossly contaminated-> tetanus
  immune globulin + toxoid booster given & penicillin administered.
• Half immune
  globulins infiltrated into wound & half given IM at separate site from tetanus
  toxoid.
• Tetanus immune globulin (tetanus antitoxin) made
  in humans to avoid serum sickness reactions occur
  when antitoxin made in horses is used.

Administration of immune globulins & tetanus toxoid (different body sites) [passive–active immunity].