Although often used synonymously, differences exist between the induction of endotoxemia and the induction of sepsis. In general, for a particular animal model, endotoxemia induction results in a more direct, reproducible alteration in host responses to the immune challenge. Sepsis induction, although less predictable and less reproducible, results in a situation more akin to that seen clinically. 3.1 Endotoxemia Endotoxin is located in the cell wall of gram negative bacteria and is responsible for the systemic alterations seen in the shock state. Referred to as the O-somatic antigen, endotoxin may successfully be removed from the cell wall with trichloracetic acid.
Endotoxemic animals exhibit changes that are species-specific.
Sensitivities to endotoxic challenges also vary among species. 3.2 Sepsis Induction of the septic state inherently is more challenging than inducing endotoxemia since the immune challenge is episodic in nature. In an effort to achieve a model similar to the situations faced by clinicians, a method which results in an episodic release of organisms into the bloodstream would be desirable. As a model of sepsis, it satisfies the requirement of episodic release of microorganisms into the bloodstream. Clearly this introduces several factors which may vary between investigators.