Exo-toxins and Endo-toxins

Question 1

Describe the difference between Exotoxin and endotoxin

Answer 1

Exotoxin - secreted

Endotoxin - released during cell lysis

Question 2

What type of bacteria normally release exotoxins?

Answer 2

Gram positive bacteria

(Exceptions = Vibrio cholerae and some strains of E. coli)

Question 3

What type of exotoxin stimulates massive release of endogenous cytokines resulting in fever, rash?

Answer 3

Pyrogenic toxins

Question 4

Staph aureus releases what pyrogenic toxin?

Answer 4

TSST-1 superantigen toxin
- causes Toxic Shock Syndrome
- Fever, rash, hypotension

Question 5

Strep pyogenes releases what pyrogenic toxins? And what do these cause?

Answer 5

Streptococcal pyrogenic exotoxin A & C

Cause scarlet fever

Question 6

Describe how ENTEROtoxins act

Answer 6

• on the gastrointestinal tract
  => diarrhoeal illness
  OR vomiting illness

Question 7

Name the enterotoxins released by the following bacteria:
1) Vibrio cholerae
2) Shigella dysenteriae
3) E-Coli
4) Staph Aureus
5) Bacillus cereus

Answer 7

1) Cholera toxin
2) Shiga toxin
3) Heat Labile toxin/ Heat stabile toxin
4) Staphylococcus aureus enterotoxin
5) Cereulide

Question 8

Give examples of neurotoxins

Answer 8

Clostridium tetani
=> Tetanospasmin
=> acts directly on nerve to cause paralysis

Clostridium botulinum
=> Botulinum toxin
=> acts at NMJ to cause paralysis

Question 9

What organisms secrete tissue-invasive toxins?

Answer 9

Clostridium perfringens
=> α-toxin, a lecithinase
=> Causes gas gangrene and haemolysis

Staph. aureus
=> Exfoliatin
=> Staph. scalded skin syndrome

Question 10

Name the toxin associated with the following organism, and its effect on the host.

Corynebacterium diphtheriae

Answer 10

Diphtheria toxin
causes mucosal cell necrosis
=> ‘diphtheric membrane’ on tonsils

Systemic distribution
= necrosis of myocardial, neural and renal tissue

Question 11

Name the toxin associated with the following organism.

Pseudomonas aeruginosa

Answer 11

Exotoxin A

Question 12

Name the toxin associated with the following organism, and its effect on the host.

Bordetella pertussis

Answer 12

Pertussis exotoxin

Impairs function of neutrophils/macrophages
=> reduced phagocytosis

Question 12

Name the toxin associated with the following organism, and its effect on the host.

Bacillus anthracis (Anthrax)

Answer 12

Oedema factor

impairs function of neutrophils/macrophages
=> reduced phagocytosis

Question 13

Where are endotoxins usually found?

Answer 13

lipopolysaccharides released from Gram-negative bacteria e.g. Neisseria meningitidis.