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

Abstract

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.