Table 1.

Features of endotoxins and exotoxins.

	Endotoxins		Exotoxins
		Type 1	Type 2	Type 3
Examples of typical diseases	Gram-negative bacteria causing sepsis	Gram-positive cocci causing toxic shock syndromes	Gram-positive anaerobes causing clostridial myonecrosis, Clostridium difficile colitis	Gram-positive anaerobes causing tetanus and botulism
Chemistry	Lipopolysaccharide	Polypeptide	Polypeptide	Polypeptide
Stimulates adaptive immune response	No	Yes	Yes	Yes
Mechanism of action	Interacts with TLR-4 and CD14, activating CD4 cells, causing the release of TNF-α and IL-1	Superantigen activates large numbers of T4-lymphocytes causing exaggerated immune response	Enzymatic or pore-forming activity, affecting cell membranes and cell matrix	A (active) and B (binding) toxins and others that can also affect cell function
Vaccines	No	No	No	Yes; toxoids used as vaccines
Heat stability	Stable at 100°C for >1 h	Destroyed by heat >60°C (except staphylococcal enterotoxin)	Destroyed by heat >60°C	Destroyed by heat >60°C
Typical bacteria	Escherichia coli, Pseudomonas and Klebsiella	Staphylococcus aureus and Streptococcus pyogenes	Clostridium perfringens and Clostridium difficile	Clostridium tetani and Clostridium botulinum