In vitro inactivation of endotoxin by polymyxin B and colistin in mastitic milk

The in vitro inactivation of crude endotoxins (lipopolysaccharides) of four Escherichia coli strains by polymyxin B and colistin in mastitic milk was investigated utilizing the Limulus amebocyte lysate test. Although minor differences were observed among the endotoxins in respect to susceptibility to inactivation, activity of each was markedly reduced by both drugs.