Synergistic antibiofilm efficacy of various commercial antiseptics, enzymes and EDTA: a study of Pseudomonas aeruginosa and Staphylococcus aureus biofilms

A multistep strategy was used to generate a combined antibiofilm treatment that could efficiently decrease the biomass of dense biofilms (≥6 × 107 CFU/cm2). Several compounds that exhibited activity against various targets were tested individually and in combination to search for possible synergistic effects. First, the antibiofilm activity of various commercially available antiseptics was tested on Pseudomonas aeruginosa and Staphylococcus aureus. Second, antiseptics were mixed with ethylene diamine tetra-acetic acid (EDTA), which is an ion chelator that can disturb biofilm organisation, and additive effects on biofilm biomass degradation were found for both strains. Then, enzymes with the ability to destabilise the biofilm matrix by hydrolysing either its proteins or its polysaccharides were used; as expected, they did not decrease bacterial viability but were revealed as efficient biomass reducers. The combination of antiseptics, EDTA and proteases, all at low concentrations, revealed a synergistic effect leading to total eradication of dense biofilms both of P. aeruginosa and S. aureus.