Genus Clostridium. C.tetani

Question 1

Classification

Answer 1

Family: bacillaceae
Genus: clostridium
Species: tetani

Found in soil test

Question 2

Morphology

Answer 2

• gram positive rods
• motile (peritrichious flagella)
• spore forming:
  Spore is at one end (“terminal spore”) so organism looks like a tennis racket

Question 3

Growth characteristics

Answer 3

obligate anaerobe

Moderately fastidious

Question 4

Antigenic structure

Answer 4

Depending on:
Flagella (H) antigen
And
Somatic (O) antigen

There are 10 serotypes

Question 5

Virulence factors

Answer 5

Exotoxin:
- tetanus toxin (tetanospasmin)
Results in extreme muscle spasm -> tetanus spastic paralysis

Tetanus toxin is a protease that cleaves proteins involved in the release of neurotransmitters = plasmid-mediated neurotoxin

• tetanolysin: liberated by those strains which do not produce tetanus toxin

Question 6

Disease

Answer 6

Generalised tetanus —> spastic paralysis
- “Risus sardonicus” = “evil grin” or “lock-jaw”

• Opisthotonous = exaggerates arching of the back

Localized tetanus —> uncommon —> occurs when low quantities of toxin are produced

Neonatal tetanus —> very high mortality rate

Cephalon tetanus —> very rare

Question 7

Microbiological diagnosis

Answer 7

• primarily a clinical diagnosis
• organisms is rarely isolated
• serologic tests not useful

Question 8

Treatment and prevention

Answer 8

Treatment:

-Hyperimmune human globulin to neutralize toxin

-Also, penicillin G and spasmolytic drugs (e.g. Valium)
> no significant resistance to penicillin

Prevention:
-Toxoid vaccine (toxoid is formaldehyde treated toxin)
> usually given to children as DTP
> tetanus boosters every 10 years