Colistin(Coly-Mycin) in Resistant Bacterial Infections

Abstract

Among the new antibiotics investigated clinically in Houston during the past two years, colistin (Coly-Mycin) has been one of the most promising. This antibiotic was isolated in Japan by Yosuo Koyama in 1950 from culture filtrates of Bacillus colistinus, a bacterium closely related to Bacillus polymyxa, the source of the polymyxins. Its pharmacology has been studied in Japan, Italy, France, and, more recently, this country. A summary of the findings of these studies indicates that the chemical, pharmacological, and antimicrobial activity of colistin is closely related to the polymyxins, Clinically, however, colistin causes fewer undesirable side-effects. Colistin is a complex polypeptide, with an empirical formula of C₄₅H₈₅O₁₀N₁₃ and a molecular weight of 969. Its acid salts are stable in solution even for very long periods; alkaline salts are less stable. It is available as colistin sulfate for oral and ophthalmic use, and as