Bacterial endotoxins and exotoxins in intensive care medicine

Bacterial infection can lead to host damage in three general ways: direct tissue damage, autoimmune mechanisms and by the release of specific bacterial toxins. Lipopolysaccharide, an endotoxin released from the cell wall of Gram-negative bacteria, plays a significant role in the pathophysiology of Gram-negative sepsis. Some bacteria secrete peptide exotoxins, which can be further classified based on their mechanism of action. Type 1 exotoxins can have superantigen activity, leading to massive T4 lymphocyte activation and dysregulated cytokine release, leading to TSS or STSS, which can be difficult to diagnose. Type 2 exotoxins can lead to cell membrane or cell matrix destruction through their enzymatic or pore-forming activity, helping bacteria to spread or causing massive tissue destruction. Type 3 exotoxins can interact with cellular mechanisms causing pathognomonic disease states.