Colistin (Polymyxin E) is an antibiotic in the Polypeptide family. It is available topical formulations. Colistin is rarely used as a treatment for acne.
Colistin is not usually active against Gram-positive bacteria. Because the acne-causing P. acnes bacterium is Gram-positive, Colistin is not expected to be a useful treatment for acne patients. Colistin is commonly used in veterinary medicine.