Colistin is an antibiotic from the group of polymyxins with bactericidal
action against Gramnegative bacteria like E. coli, Haemophilus and
Salmonella spp. Polymyxins interact strongly with phospholipids and
penetrate into and disrupt the structure of cell membranes. Colistin
sulphate is poorly absorbed after oral administration, and serum
concentrations are generally undetectable. Orally administered
colistin is eliminated almost totally in faeces.