Disruption of Biofilms and Neutralization of Bacteria Using Hypochlorous Acid Solution: An In Vivo and In Vitro Evaluation

ABSTRACT OBJECTIVES: The aims of this study were to assess the effectiveness of a hypochlorous acid–based wound cleanser (Vashe Wound Solution [VWS], SteadMed Medical, Fort Worth, Texas) in disrupting methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa biofilms relative to other cleansers using an in vitro collagen biofilm model and to evaluate cleansers’ cytotoxicity. The bioburden reduction of venous stasis wounds by VWS and another cleanser was evaluated. METHODS: Plates coated with collagen films incubated with active bacteria cultures to yield biofilm mimics were treated with VWS, 1% and 10% povidone-iodine (PI), 0.05% chlorhexidine wound solution (CWS), or normal saline for 3 or 10 minutes. Biofilms were then analyzed for biomass density using a crystal violet assay, quantitative cultures, and fluorescent microscopy. Cytotoxicity was measured using neutral red uptake by primary human dermal fibroblasts. Pre- and postcleansing exudates and swab samples obtained from venous stasis wounds of patients were processed and plated on a series of selective agar plates for bacteria typing and quantification. RESULTS: All agents tested significantly neutralized methicillin-resistant S aureus and P aeruginosa biofilms compared with saline control as assessed by crystal violet assay and fluorescent microscopy assays. Undiluted VWS was significantly less cytotoxic compared with 1% PI, CWS, and 10% PI (in increasing order of cytotoxicity). There was no significant difference in bacterial reduction in wounds after treatment with VWS or CWS for any type of bacteria examined using selective media. In wounds that were treated with VWS or CWS, there was a similar percentage reduction in bacterial colony-forming units from precleansing levels when plated on tryptic soy agar, MacConkey, streptococcal, and mannitol salt agar plates. Plates treated with CWS trended toward higher bacterial reduction on nonselective and gram-negative agars, whereas VWS trended toward higher bacterial reduction in Streptococcus -selective agars. CONCLUSIONS: These findings support the use of VWS in the treatment of wounds with biofilms and to reduce the bioburden of venous stasis ulcers. While VWS-treated biofilms had higher biomass than CWS- and saline-treated biofilms, most of the cellular component was not viable. Ultimately, VWS had a similar effectiveness to CWS in eliminating bacteria but with lower cytotoxicity.