A mixture of polymyxins B1 and B2, obtained from Bacillus polymyxa strains. They are basic polypeptides of about eight amino acids and have cationic detergent action on cell membranes. Polymyxin B is used for infections with gram-negative organisms, but may be neurotoxic and nephrotoxic.

Basic lipopeptide antibiotic group obtained from Bacillus polymyxa. They affect the cell membrane by detergent action and may cause neuromuscular and kidney damage. At least eleven different members of the polymyxin group have been identified, each designated by a letter.

Cyclic polypeptide antibiotic from Bacillus colistinus. It is composed of Polymyxins E1 and E2 (or Colistins A, B, and C) which act as detergents on cell membranes. Colistin is less toxic than Polymyxin B, but otherwise similar; the methanesulfonate is used orally.

Substances that reduce the growth or reproduction of BACTERIA.