An evaluation of hypochlorous acid-based wound cleansers to reduce bioburden using an in vitro based wound model

Introduction: The clinical use of pure hypochlorous acid(pHA/HOCl)-based wound cleansers has gained widespread adoption for a number of reasons, such as their mildly acidic nature, they exhibit rapid and broad-spectrum antimicrobial(AM) properties, and their clinically proven ability to lower the bioburden within wounds.  In the past, pre-clinical in vitro assays that were used to evaluate the biocidal properties of pHA/HOCl-based cleanser utilized microbes in a purely planktonic(free-floating) state.  Although this approach yielded useful quantitative data, the clinical relevance of this data may be limited since bacteria within a wound do not exist solely in a planktonic state, but also in a sessile(adherent) state and in biofilms.  This study evaluates the effectiveness of pHA/HOCl-based wound cleansers at reducing/removing bacterial bioburden from within a simulated contaminated wound environment using an in vitro assay in which bacteria are present in an adherent state rather than a planktonic state. Methods:Petri dishes containing general-purpose culture medium/agar were inoculated with a 1:10 dilution of clinically relevant pathogenic bacteria.  A 2.5cm x 2.5cm gauze pad saturated with the wound cleanser being examined was placed onto the inoculated agar surface and incubated for various time points up to 24 hours.  Plates were visually inspected for the presence/absence of bacterial colonies on the agar surface surrounding the treated gauze (zone-of-inhibition(ZOI)) and directly under it.  Two different pHA/HOCl-based wound cleansers were compared to other commercially available cleansers containing alternative preservatives/disinfectants and a PBS negative control.  Results:All wound cleansers containing an AM preservative/disinfectant inhibited bacterial growth on the agar in direct contact with the treated gauze, whereas the PBS treated negative control did not.  Additionally, AM containing wound cleansers inhibited bacterial growth around the gauze in a ZOI that appeared to be directly correlated with the preservative/disinfectant agent used and contact period, with pHA/HOCl-based cleanser exhibiting a ZOI of up to 13mm. Discussion: These results demonstrate that HSAM maintains the native characteristics of unprocessed amniotic membranes, and this preserved ECM and structure functions as a scaffold in vitro.The semi-quantitative assay used provides additional insight into the performance of pHA/HOCl wound cleansers at reducing the bioburden of pathogenic bacteria in a simulated wound environment.  Additionally, this study provides data-supported recommendations for the further refinement of clinical protocols involving wound cleansers to improve microbial bioburden reduction.References: