Polymyxin antibacterial, bactericidal.
Acts mainly on gram-negative microorganisms. It is absorbed on membrane phospholipids, increases its permeability, and causes lysis of bacteria. Resilience develops slowly; causes cross-resistance with colistin. It is active against Salmonella, Shigella, E. coli, Klebsiella spp., Bordetella pertussis, Haemophilus influenzae, Enterobacter, Pseudomonas aeruginosa, Vibrio cholerae (except for the eltor type).