TOXICITY OF POLYMYXIN B

Abstract

THE POLYMYXINS comprise a group of antibiotics produced by different strains of a Gram-positive spore-forming bacillus, Bacillus polymyxa. In July 1947, the antibiotic properties of substances derived from strains of this organism were reported independently by Stansly, Shepherd, and White¹ and by Benedict and Langlykke.² Simultaneously another strain was being studied by Ainsworth, Brown, and Brownlee,³ in the Wellcome Physiological Research Laboratories in England, and their work was reported the following month. The strain from which the antibiotic was isolated by the English group was originally called Bacillus aerosporus and the antibiotic was called "Aerosporin." It was subsequently determined that the three groups were working with different strains of B. polymyxa, and the generic name of "polymyxin" was adopted for the antibiotics derived from this micro-organism. Chemical investigations⁴ revealed that the various polymyxins were basically polypeptides and varied in their amino acid content. The polymyxin isolated in this country was