Mouse Anti-Gram-negative bacteria Endotoxin Monoclonal antibody for IA. Endotoxins are part of the outer membraneof the cell wall of gram negative bacteria. Endotoxins are invariablyassociated with gram negative bacteria whether the organisms are pathogens ornot. Although the term "endotoxin" is occasionally used to refer toany cell associated bacterial toxin, it is properly reserved to refer to thelipopolysaccharide complex associated with the outer membrane ofgram-negative bacteria such as E. coli, Salmonella, Shigella, Pseudomonas,Neisseria, Haemophilus, and other leading pathogens.