In Vitro Antibacterial Activity of Hydrogen Peroxide and Hypochlorous Acid, Including That Generated by Electrochemical Scaffolds

Abstract

Hydrogen peroxide (H2O2) and hypochlorous acid (HOCl) are biocides used for cleaning and debriding chronic wound infections, which often harbor drug resistant bacteria. Here, we evaluated the in vitro activity of H2O2 and HOCl against 27 isolates of eight bacterial species involved in wound infections. Minimum inhibitory concentrations (MICs) and minimum biofilm bactericidal concentrations (MBBCs) were measured. When compared to their respective MICs, MBBCs of isolates exposed to H2O2 were 16- to 1,024-fold higher and those exposed to HOCl were 2- to 4-fold higher. We evaluated selection of resistance after exposure of Staphylococcus aureus and Pseudomonas aeruginosa biofilms to 10 iterations of electrochemically generated HOCl or H2O2 delivered using electrochemical scaffolds (e-scaffolds), observing no decrease in anti-biofilm effects with serial exposure to e-scaffold-generated H2O2 or HOCl. 24-hour exposure to H2O2-generating e-scaffolds consistently decreased colony forming units (CFUs) of S. aureus and P. aeruginosa biofilms by ∼5.0-log10 and ∼4.78-log10 through 10 iterations of exposure, respectively. 4-hour exposure to HOCl-generating e-scaffolds consistently decreased CFUs of S. aureus biofilms by ∼4.9-log10, and 1-hour exposure to HOCl-generating e-scaffolds consistently decreased CFUs of P. aeruginosa biofilms by ∼1.57-log10. These results suggest that HOCl has similar activity against planktonic and biofilm bacteria, whereas the activity of H2O2 is less against biofilm than planktonic bacteria, and that repeat exposure to either biocide, generated electrochemically under the experimental conditions studied, does not lessen antibiofilm effects.

Efficacy and toxicity of hydrogen peroxide producing electrochemical bandages in a porcine explant biofilm model

“…Two devices have been developed based on an electrochemical H 2 O 2 concept: e‐scaffolds were developed to assess activity against biofilms grown in liquid growth media, and then e‐bandages were developed to treat agar membrane (and eventually wound) biofilms. e‐Scaffolds demonstrated anti‐biofilm efficacy against mono‐, dual‐ and tri‐species bacterial and fungal biofilms, without significant toxicity to host tissue in an ex vivo porcine explant model (Raval et al, 2019 , 2020 ; Raval, Flurin, et al, 2021 ; Sultana et al, 2015 , 2016 ). In addition, it was suggested that H 2 O 2 generation by the electrode was the dominant mechanism of action (Sultana et al, 2015 ).…”

Hydrogen-peroxide generating electrochemical bandage is active in vitro against mono- and dual-species biofilms

“…S2 ). Through continuous production of H 2 O 2 and based on results herein and previously described [ 20 , 46 ], it may be possible that the described e-bandage system can overwhelm some of these oxidative stress response systems.…”

“…Biofilms formed by a catalase mutant isolate of P. aeruginosa were sensitive to H 2 O 2 . In recent work, it was demonstrated that P. aeruginosa PA14 ΔkatAB had lower minimum biofilm inhibitory and minimum biofilm bactericidal concentrations compared to its wild type parent isolate P. aeruginosa PA14 [ 46 ]. Moreover, in the current work, an increase in biofilm reduction of P. aeruginosa PA14 ΔkatAB compared to its wild type parent isolate P. aeruginosa PA14 was observed when exposed to an H 2 O 2 -producing e-bandage for 24 h ( Supplementary Fig.…”

Hypochlorous Acid-Generating Electrochemical Catheter Prototype for Prevention of Intraluminal Infection

“…In previous work, Raval et al ( 27 ) determined the MICs of HOCl for 27 isolates, including S. aureus , S. epidermidis , E. faecium , and E. coli . The MICs for 6 S. aureus and 3 S. epidermidis isolates ranged from 990 to 1,690 μM, and the MICs for E. faecium and E. coli isolates were 990 μM HOCl; concentrations above 286 μM are cytotoxic to mammalian cells ( 28 ).…”