BoardVitals Microbiology Practice Test 2025 - Free Microbiology Practice Questions and Study Guide

Gram-negative bacteria release endotoxins upon cell lysis. Endotoxins are components of the outer membrane of these bacteria, specifically lipopolysaccharides (LPS). When the bacterial cells die and break down, these molecules are released into the surrounding environment.

Endotoxins are known to trigger a strong immune response in the host, leading to symptoms such as fever, inflammation, and, in severe cases, septic shock. This is in contrast to exotoxins, which are produced and secreted actively by both Gram-positive and Gram-negative bacteria, and can have varied effects on host cells. Unlike exotoxins, endotoxins are not secreted actively and are not proteins; they are structural components of the bacteria’s outer cell membrane.

Cytotoxins and neurotoxins are specific types of exotoxins that affect different types of cells. Cytotoxins can damage a variety of host cells, while neurotoxins specifically target nerve cells. Endotoxins, on the other hand, are elicited from the destruction of the bacterial cell itself, rather than being actively secreted. This distinction is essential in understanding how different types of toxins affect the host organism.