The polymyxins are active against Gram negative organisms including Pseudomonas Sp. They can only be given systemically and because they are toxic have few indications. They are used in some topical applications, for example bladder irrigants.
The polymyxins are polypeptides with a ling hydrophobic tail which act as cationic detergents, binding the bacterial cell membrane and resulting in leakage of the cytoplasmic contents.
Last reviewed 01/2018