theme 6(2)Exotoxins

• AB toxins

  • 2 subunits: A and B
  • B unit binds to host cell receptor and transfer damaging agent (A) across cell membrane
  • Eg. Tetanus toxin, botulium toxin
  • Enterotoxin: Produced by Vibrio cholerae (Cholera toxin)
• Cytolytic Exotoxins

  • Degrade cytoplasmic membrane integrity, cause cell lysis and death.
  • Lyse red blood cells = hemolysins
  • Clearing zone of Streptococcus pyogenes
• Superantigen exotoxin

  • Cause over stimulation of the immune systems
  • Lead to shock and death
  • Due to localized infection (systemic effect)
  • Produced by gram (+) Staphylococcus aureus & S. pyogenes
  • Can be triggered by food poisoning, TSS or pyrogenic fever.