Colistin is a polymyxin antimicrobial that is used in the treatment of severe Gram negative infections, especially those due to Escherichia coli and Salmonella spp. It is used by the oral route for the treatment of gastro-intestinal infections or for selective decontamination of the gastro-intestinal tract in animals at high risk of endogenous infections. The development of resistance to colistin is rare.

It is indicated for use in pigs (in particular sucking and post weaning) for the treatment of colibacillosis.