Synergistic Effect and Antibiofilm Activity of a Skin and Wound Cleanser

Biofilm in chronic wounds impedes the wound healing process. Each biofilm has differing characteristics requiring a multifaceted approach for removal while maintaining a surrounding environment conducive to wound healing.

In this study, 3 of the components in a wound cleanser are tested to determine synergy in eradicating biofilms of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa in vitro.

The 3 components assessed for synergy were ethylenediamine tetraacetic acid sodium salts (EDTA), vicinal diols (VD; ethylhexylglycerin and octane-1,2-diol), and polyhexamethylene biguanide (PHMB). Each component was assessed individually and in combination while dissolved in a base solution. The Calgary assay method was used for biofilm growth and treatment. Kull Equation analysis for synergy was conducted using viable count results.

Synergy is defined as the interaction of components to produce a combined effect greater than the sum of their separate effects. The base solution containing all 3 components (EDTA, VD, and PHMB) reduced biofilm viability by more than 5 logs, demonstrating statistically significant synergy. The 3 components tested individually in the base solution resulted in the following: EDTA did not reduce bacteria viability; VD reduced viability by about 1 log; and PHMB reduced P aeruginosa viability by about 2.5 logs and MRSA viability by about 4 logs. Of importance, the MRSA biofilm failed to regrow in the recovery plates after combined treatment, indicating complete elimination of the biofilm bacteria.

The experimental and calculated results indicate the 3 components (VD, EDTA, and PHMB) when used together act synergistically to eradicate MRSA and P aeruginosa biofilms in vitro.