Definition

1. Noun:
   • A poisonous substance released by a living microorganism: An exotoxin is a type of toxin that is actively secreted or released by certain bacteria and other microorganisms into their surrounding environment (e.g., tissue, bloodstream, or growth medium). It is distinct from endotoxins, which are part of the bacterial cell wall and are released only when the bacterium disintegrates.

Usage Examples

• Noun:
  • The disease's severe symptoms are primarily caused by a potent exotoxin produced by the bacteria.
  • Scientists are studying the structure of the exotoxin to develop an effective antitoxin.
  • Unlike endotoxins, exotoxins are typically proteins and can be neutralized by specific antibodies.

Advanced Usage

• In medical microbiology: The term is used to classify bacterial toxins based on their origin and release mechanism. Exotoxins are often major virulence factors.
  • The exotoxin produced by Corynebacterium diphtheriae inhibits protein synthesis in host cells.
• In public health: Reference to exotoxins is common in discussions of food poisoning, certain types of sepsis, and vaccine development.
  • Tetanus and botulism are diseases mediated by powerful neurotoxic exotoxins.

Variants and Related Words

• Exotoxic (adj): Relating to or caused by an exotoxin.
  • The infection had an exotoxic effect on the nervous system.
• Endotoxin (n): A toxin that is part of the outer membrane of certain bacteria and is released when the bacterium lyses or disintegrates. (This is a related but distinct concept).
• Enterotoxin (n): A type of exotoxin that targets the intestines, often causing vomiting and diarrhea.

Synonyms

• Secreted toxin: A descriptive synonym emphasizing the release mechanism.
• Bacterial toxin: A broader term that can encompass both exotoxins and endotoxins.

Related Phrases and Collocations

• Produce an exotoxin: The action of the microorganism.
  • The strain was found to produce an exotoxin.
• Exotoxin-mediated disease: A disease where the primary damage is caused by the exotoxin.
  • Diphtheria is a classic example of an exotoxin-mediated disease.
• Neutralize an exotoxin: The action of an antitoxin or antibody.
  • The antiserum helps neutralize the circulating exotoxin.

Noun

1. a toxin that is secreted by microorganisms into the surrounding medium