A novel micellar formulation based on natural plant extracts enhances the efficacy of hydrogen peroxide against biofilms of Staphylococcus spp. and Pseudomonas aeruginosa.

The antibacterial efficacy of hydrogen peroxide encapsulated in micelles (mH2O2) against biofilms was compared with that of hydrogen peroxide alone and of three commercially available aqueous biocides. The activity of mH2O2 on 24-h biofilms of reference strains of Staphylococcus spp. and Pseudomonas aeruginosa was tested in a static microtiter plate model. The biofilms were incubated with mH2O2 (17% v/v H2O2, 2% lactic acid, 0.3% phytoextract, H2O) and its individual ingredients and compared with three aqueous biocides at different concentrations and times of exposure. After 5-min exposure, 10% mH2O2 (corresponding to 1.7% v/v H2O2) achieved > 8 log10 reductions against all the test strains, while 1.7% H2O2 achieved a maximum of 1.5 log10 reduction. After 5-min exposure, none of the commercially available biocides tested showed themselves to be capable of completely eliminating the test strains embedded in biofilms. Hydrogen peroxide encapsulated in micelles demonstrated enhanced activity against planktonic cells and biofilms of Staphylococcus spp. and P. aeruginosa.