How do endotoxins differ from exotoxins?

Endotoxins and exotoxins represent two distinct categories of bacterial toxins, each with unique characteristics and mechanisms of action. The correct choice highlights a key difference: endotoxins are typically released only when the bacterial cell is lysed or destroyed. This release occurs when Gram-negative bacteria die and their cell walls are broken down, releasing lipopolysaccharides, which constitute the endotoxin. The immune response to endotoxins can lead to inflammation and can contribute to septic shock in severe cases.

In contrast, exotoxins are actively secreted by living bacteria, particularly Gram-positive bacteria, into their environment. These toxins are proteins and they exhibit a wide range of biological activities that can lead to specific symptoms and diseases. This distinction is essential in understanding the pathogenicity mechanisms employed by different bacterial species.

The other choices do not accurately reflect the fundamental differences between endotoxins and exotoxins. Recognizing these differences is crucial for understanding how bacterial infections can affect host organisms and for developing appropriate treatment strategies.