Exotoxin and Endotoxin


Name the exotoxin and endotoxin producing bacteria:

[A]Endotoxin producing bacteria:

  • E.coli.
  • Klebsiella.
  • Salmonella.
  • Shigella.
  • Proteus.
  • Brucella.
  • Neisseria.

[B]Exotoxin producing bacteria:

a) Gram(+ ve)bacteria:

  • Clostridium tetani.
  • Clostridium botulinum.
  • Clostridium defficile.
  • Clostridium perfingens.
  • Bacillus anthracis.

b) Gram(- ve)bacteria:

  • Vibriocholera.
  • Pseudom Aeromonas.
  • Bordetella parteusis.
  • Aeromonas.

Difference between exotoxin & endotoxin:




(1)Excreted by living cells. (1)Integral part of the cell wall.Relased on bacterial disintegration.
(2)Produced by Gram positive and Gram negative bacteria. (2)Formed only by Gram negative bacteria.
(3)Polypeptides. (3)Lipopolysaccharides lipid A is toxic.
(4)Usually binds to specific receptors on cells. (4)No specific receptors.
(5)Highly toxic.Fatal in small doses. (5)Moderately toxic.Fatal in large doses.
(6)Relatively heat labile.Toxicity destroyed over 60 c. (6)Relatively heat stable.Toxicity is not destroyed above 60 c for hours.
(7)Highly antigenic.Stimulates formation of antitoxin.Antitoxin neutralizes the toxin. (7)Weakly antigenic.Antibodies are protective but to a lesser extent than antitoxin.
(8)May be converted to toxoid by formalin. (8)Not coverted to toxoid.
(9)Usually under cotrol of extra chromosomal genes. (9)Under control of chromoosmal genes.
(10)Usually do not produce fever. (10)Usually produce fever.

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