What is an endotoxin?

An endotoxin is defined as a component of the outer membrane of certain bacteria, particularly Gram-negative bacteria. This toxin is an integral part of the bacterial cell wall and is not released until the bacteria die and the cell walls break down. The most well-known endotoxin is lipopolysaccharide (LPS), which triggers significant immune responses in humans and other organisms.

Endotoxins can lead to fever, inflammation, and even septic shock in severe cases when they enter the bloodstream. The distinction between endotoxins and exotoxins (which are actively secreted proteins produced by living bacteria) is crucial in microbiology and pathogenesis. Endotoxins are less potent than many exotoxins but are still significant due to their ability to induce strong immune reactions.

This understanding clarifies why the definition of an endotoxin as part of the outer membrane of certain bacteria is accurate, highlighting its role in pathogenicity and immune response.