Investigation of Synergism with Combinations of Dibromopropamidine Isethionate or Propamidine Isethionate and Polymyxin B

Combinations of polymyxin B and dibromopropamidine isethionate exhibited synergistic inhibitory and bactericidal activity against Pseudomonas aeruginosa, Enterobacter cloacae, Proteus mirabilis, Escherichia coli and Staphylococcus aureus. Similar results were obtained with polymyxin B plus propamidine combinations except that propamidine was not as active as dibromopropamidine and the combination of polymyxin B plus propamidine against S. aureus only had additive activity. The antibacterial agents were tested in solutions and in a cream formulation. The findings indicate a potential for the use of selected combinations of these antibacterial agents in the treatment of wound and superficial eye infections.