5.2 TOXINS

 Give examples of diseases primarily caused by effect of toxin.

The text provides examples of diseases that are primarily caused by the effect of bacterial toxins. These toxins have unique mechanisms of action, leading to specific disease symptoms:

Diphteria toxin+ Cholera toxin + Tetanus toxin+ Enterotoxin of S. aureus+ Botulinum toxin+ Pseudomonas toxin A + Shigella toxin 

Diphtheria toxin:

  • Mechanism: This toxin is classified as an A-B exotoxin. It acts by inactivating the elongation factor involved in protein synthesis. Without this factor, cells cannot make proteins.

  • Effect: The inability to synthesize proteins leads to cell death.

  • Disease: The end result is diphtheria, a serious respiratory illness.

Cholera toxin:

  • Mechanism: This toxin causes an increase in cyclic AMP (cAMP) inside cells.

  • Effect: Elevated cAMP levels lead to the loss of ions and water from cells.

  • Disease: The main symptom is watery diarrhea, characteristic of cholera.

Tetanus toxin:

  • Mechanism: It acts by decreasing the release of neurotransmitters from inhibitory neurons in the nervous system.

  • Effect: This results in overstimulation of muscles.

  • Disease: The end result is spastic paralysis, the main feature of tetanus.

Enterotoxin of S. aureus:

  • Effect: It leads to symptoms when ingested with contaminated food.

  • Disease: The condition is commonly known as food poisoning or staphylococcal food poisoning.

Botulinum toxin:

  • Mechanism: This toxin prevents the release of acetylcholine (ACh) in motor neurons.

  • Effect: Without ACh, muscles do not receive signals to contract.

  • Disease: The result is flaccid paralysis, which is seen in botulism.

Pseudomonas exotoxin A:

  • Mechanism: It has a similar mode of action as the diphtheria toxin, which means it inhibits protein synthesis.

  • Effect: This leads to cell death.

  • Disease: Can cause a variety of infections, especially in immunocompromised individuals.

Shigella toxin:

  • Mechanism: The toxin inhibits protein synthesis, leading to cell death. Additionally, Shigella bacteria also have LPS (endotoxin).

  • Disease: The primary disease is gastroenteritis, an inflammation of the stomach and intestines, leading to symptoms like diarrhea.

In summary, these toxins, produced by different bacteria, interfere with essential cellular processes or disrupt cellular structures, leading to specific diseases. The toxins often target specific cells or tissues, which determines the symptoms of the disease they cause.

Mind Map: Diseases Primarily Caused by Effect of Toxin

Central Idea: Diseases caused by bacterial toxins have unique mechanisms of action, leading to specific disease symptoms.

Diphtheria Toxin

  • Mechanism: A-B exotoxin, inactivates elongation factor in protein synthesis

  • Effect: Inability to synthesize proteins leads to cell death

  • Disease: Diphtheria, a serious respiratory illness

Cholera Toxin

  • Mechanism: Increases cyclic AMP (cAMP) inside cells

  • Effect: Loss of ions and water from cells

  • Disease: Watery diarrhea, characteristic of cholera

Tetanus Toxin

  • Mechanism: Decreases release of neurotransmitters from inhibitory neurons

  • Effect: Overstimulation of muscles

  • Disease: Spastic paralysis, main feature of tetanus

Enterotoxin of S. aureus

  • Effect: Symptoms when ingested with contaminated food

  • Disease: Food poisoning or staphylococcal food poisoning

Botulinum Toxin

  • Mechanism: Prevents release of acetylcholine (ACh) in motor neurons

  • Effect: Muscles do not receive signals to contract

  • Disease: Flaccid paralysis, seen in botulism

Pseudomonas Exotoxin A

  • Mechanism: Inhibits protein synthesis

  • Effect: Cell death

  • Disease: Can cause various infections, especially in immunocompromised individuals

Shigella Toxin

  • Mechanism: Inhibits protein synthesis, also has LPS (endotoxin)

  • Disease: Gastroenteritis, inflammation of stomach and intestines, leading to diarrhea

In summary, bacterial toxins interfere with cellular processes or disrupt structures, causing specific diseases. The target cells or tissues determine the symptoms of the disease.