Plate 50
Toxins
Toxins
• Toxins: poisonous substances produced by
organisms (microorganisms, in our case)
Exotoxins
• Exotoxins: produced within
cytoplasm of bacteria and
released into the
surrounding environment
– Exo = “out”
– Produced by Gram-positive
bacteria
– Toxins are soluble in body
fluids
Exotoxins
• Released after bacteria cell is inside the body
or in food (and consumed by host)
• Spread through body by blood and damage
organs
• Effects of exotoxins:
– Damage cell membranes of tissue
– Interrupt metabolic function
– Interfere with cellular functions
Exotoxins – Enterotoxin
• Staphylococcus aureus produce enterotoxins that
are absorbed by the cells that line the intestines
• Entero = “intestine”
• Symptoms:
–
–
–
–
Nausea
Vomiting
Abdominal cramps
Diarrhea
• Ex: S. aureus can result in Toxic Shock Syndrome,
commonly found in menstruating women who
use tampons
Staphylococcus aureus – “golden
cluster seed”
Staph Infection
• Skin infections:
– Pimples
– Folliculitis
– Impetigo
Exotoxins – Neurotoxin
• Clostridium botulinum produce neurotoxins
that affect the nervous system
• Neuro = “nerve”
• Prevents the release of acetylcholine (a
neurotransmitter) at neuromuscular junctions
• Results in paralysis, since nerve impulses
cannot pass to muscles
Botulism
Exotoxins – Neurotoxin
• Clostridium tetani
produce a neurotoxin
that affects nerve cells
responsible for skeletal
muscle contractions
• Muscles remain
constantly contracted
and rigid
Tetanus
• “Lock-jaw” – muscle
contraction in the face
and neck
Tetanus
Exotoxins – Cytotoxin
• Corynebacterium diphtheriae kill respiratory
cells by interfering with protein synthesis
• Dead respiratory cells and debris collect in
mucus, block small air passageways, and make
breathing difficult
• Cyto = “cell”
Diptheria
• Note the large whitish
swelling in the throat
Endotoxins
• Endotoxins: made of
components of bacterial cell
wall
– Endo = “in”
– Produced by Gram-negative
bacteria
– Made of lipopolysaccharides
(LPS)
– Released when the bacteria
cell wall is broken down
(through phagocytosis or
antibiotics)
Endotoxins
• Unlike some exotoxins, endotoxins are not tissue
specific – they affect a wide range of tissues
(systemic)
• Symptoms:
–
–
–
–
–
–
Dilate blood vessels (lower blood pressure)
Tissue failure due to lack of nutrition and oxygen
Fever
Muscular weakness
Low levels of white blood cells
Hemorrhaging of blood vessels