TLR4 and Sepsis: On the other hand, it has been experimentally shown that even ABCoR clinical strains recovered during colistin therapy progressively increase their virulence under oxidative stress [57], and when macrophages-, complement-, or neutrophil-related host defense mechanisms are depleted, even avirulent AB strains trigger a lethal lipopolysaccharide Toll-like receptor 4 (TLR-4) mediated sepsis response [46,58].