Colistimethate

**Semantic type:** Pharmacologic Substance

**Definition:** A broad-spectrum polymyxin antibiotic against most aerobic Gram-negative bacteria except Proteus bacteria. Colistimethate is a mixture of methanesulfonate derivatives of cyclic polypeptides colistin A and B from Bacillus colistinus or B. polymyxa. Colistin functions as a surfactant which penetrates into and disrupts the bacterial cell membrane, thereby resulting in bactericidal effect.

**Synonyms:** - COLISTIMETHATE