Colistin is a bactericidal drug that binds to lipopolysaccharides and phospholipids in the outer cell membrane of Gram-negative bacteria. It competitively displaces divalent cations from the phosphate groups of membrane lipids, which leads to disruption of the outer cell membrane, leakage of intracellular contents, and bacterial death. In addition to its bactericidal effect, colistin can bind and neutralize lipopolysaccharide (LPS) and prevent the pathophysiologic effects of endotoxin in the circulation Susceptibility breakpoints for colistin have been developed in France, Germany and the UK that are very conflicting to each other.
The breakpoints for susceptibility are based on colistin sulfate. The French Society for Microbiology has selected ≤2 mg/l as the susceptibility breakpoint and >2 mg/l as the resistance breakpoint for Enterobacteriaceae, while the British Society for…
