ABSTRACT
Chronic wound infections can be difficult to treat and may lead to impaired healing and worsened patient outcomes. Novel treatment strategies are needed. This study evaluated effects of intermittently produced H2O2 and HOCl, generated via an electrochemical bandage (e-bandage), against methicillin-resistant Staphylococcus aureus biofilms in an agar membrane biofilm model. By changing the working electrode potential, the e-bandage generated either HOCl (1.5 VAg/AgCl) or H2O2 (-0.6 VAg/AgCl). The degree of biocidal activity of intermittent treatment with HOCl and H2O2 correlated with HOCl treatment time; HOCl treatment durations of 0, 1.5, 3, 4.5, and 6 hours (with the rest of the 6 hour total treatment time devoted to H2O2 generation) resulted in mean biofilm reductions of 1.36±0.2, 2.22±0.16, 3.46±0.38, 4.63±0.74 and 7.66±0.5 log CFU/cm2, respectively vs. non-polarized controls, respectively. However, application of H2O2 immediately after HOCl treatment was detrimental to biofilm removal. For example, 3-hours HOCl treatment followed by 3-hours H2O2 resulted in a 1.90±0.84 log CFU/cm2 lower mean biofilm reduction than 3-hours HOCl treatment followed by 3-hours non-polarization. HOCl generated over 3-hours exhibited biocidal activity for at least 7.5-hours after e-bandage operation ceased; 3-hours of HOCl generation followed by 7.5-hours of non-polarization resulted in a biofilm cell reduction of 7.92±0.12 log CFU/cm2 vs. non polarized controls. Finally, intermittent treatment with HOCl (i.e., interspersed with periods of e-bandage non-polarization) for various intervals showed similar effects (approximately 6 log CFU/cm2 reduction vs. non-polarized control) to continuous treatment with HOCl for 3-hours, followed by 3-hours of non-polarization. These findings suggest that timing and sequencing of HOCl and H2O2 treatments are crucial for maximizing biofilm control.
ABSTRACT
A novel electrochemical bandage (e-bandage) delivering low-level hypochlorous acid (HOCl) was evaluated against Pseudomonas aeruginosa murine wound biofilms. 5 mm skin wounds were created on the dorsum of Swiss-Webster mice and infected with 10 6 colony forming units (CFU) of P. aeruginosa . Biofilms were formed over two days, after which e-bandages were placed on the wound beds and covered with Tegaderm™. Mice were administered Tegaderm-only (control), non-polarized e-bandage (no HOCl production), or polarized e-bandage (using an HOCl-producing potentiostat), with or without concurrently administered systemic amikacin. Purulence and wound areas were measured before and after treatment. After 48 hours, animals were sacrificed, and wounds were harvested for bacterial quantification. Forty-eight hours of polarized e-bandage treatment resulted in mean biofilm reductions of 1.4 log 10 CFUs/g (9.0 vs 7.6 log 10 ; p = 0.0107) vs non-polarized controls, and 2.2 log 10 CFU/g (9.8 vs 7.6 log 10 ; p = 0.004) vs Tegaderm only controls. Systemic amikacin improved CFU reduction in Tegaderm-only (p = 0.0045) and non-polarized control groups (p = 0.0312), but not in the polarized group (p = 0.3876). Compared to the Tegaderm only group, there was more purulence reduction in the polarized group (p = 0.009), but not in the non-polarized group (p = 0.064). Wound closure was not impeded or improved by either polarized or non-polarized e-bandage treatment. Concurrent amikacin did not impact wound closure or purulence. In conclusion, an HOCl-producing e-bandage reduced P. aeruginosa in wound biofilms with no impairment in wound healing, representing a promising antibiotic-free approach for addressing wound infections.
