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Plate 50

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

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Plate 50

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  1. Plate 50 Toxins

  2. Toxins • Toxins: poisonous substances produced by organisms (microorganisms, in our case)

  3. 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

  4. 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

  5. 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

  6. Staphylococcus aureus – “golden cluster seed”

  7. Staph Infection • Skin infections: • Pimples • Folliculitis • Impetigo

  8. 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

  9. Botulism

  10. Exotoxins – Neurotoxin • Clostridium tetani produce a neurotoxin that affects nerve cells responsible for skeletal muscle contractions • Muscles remain constantly contracted and rigid

  11. Tetanus • “Lock-jaw” – muscle contraction in the face and neck

  12. Tetanus

  13. 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”

  14. Diptheria • Note the large whitish swelling in the throat

  15. 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)

  16. 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

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