Polymyxin B-sulfate

Polymyxin B-sulfate is a polypeptide antibiotic from Bacillus polymyxa (C₅₅H₉₆N₁₆O₁₃x2H₂SO₄, MW 1385.63). Polymyxin is active against only Gram-negative bacteria, also against non-proliferating bacteria.

mechanism: Binding to lipopolysaccharides of the Gram-negative bacteria leads to a permeabilisation of the cell membrane. This results in loss of ions (Fe²⁺, Mn²⁺, Ca²⁺, Mg²⁺), unsaturated fatty acids and polyphosphate.