Antibiofilm efficacy of stabilised hypochlorous acid
Abstract:
Background: Catheter-related bloodstream infections (CRBSIs) remain a clinical challenge due to intraluminal biofilm formation. Conventional antibiotic and ethanol lock therapies are limited by antimicrobial resistance, incomplete penetration, and cytotoxicity. Stabilised hypochlorous acid (HOCl), a potent oxidant with antimicrobial properties, has emerged as a potential alternative; however, its stabilised formulation differs from transient neutrophil-derived HOCl.
Objective: To evaluate the antibiofilm efficacy and cytotoxic profile of HOCl compared to high-dose ciprofloxacin and ethanol in an in vitro catheter lock model.
Methods: Staphylococcus aureus (ATCC 35556) biofilms were established on catheter segments. Treatment efficacy was assessed over 4 days using crystal violet staining and scanning electron microscopy (SEM). HOCl and ethanol were applied at their minimum bactericidal concentrations (MBC), while ciprofloxacin was used at 500× MIC to represent high-level antibiotic exposure. Cytotoxicity was evaluated by morphological analysis of Giemsa-stained peripheral blood smears.
Results: HOCl and ethanol reduced biofilm biomass to levels comparable to sterile controls. Ciprofloxacin failed to significantly reduce biofilm biomass and was associated with increased biomass. SEM confirmed marked disruption of biofilm architecture following HOCl exposure. Morphologically, ethanol induced erythrocyte lysis and ciprofloxacin promoted rouleaux formation, whereas HOCl preserved cellular morphology without overt morphological evidence of cellular damage.
Conclusion: Stabilised HOCl demonstrated substantial antibiofilm activity while preserving cellular morphology under the conditions tested. These findings suggest that HOCl may represent a promising candidate for catheter-related infection prevention, although further studies incorporating functional cytotoxicity assays are required.
Reference:
Daştan N, Sakarya S. Hypochlorous acid demonstrates antibiofilm activity with preserved cellular morphology in an in vitro comparison with ciprofloxacin and ethanol. J Hosp Infect. 2026 May 27:S0195-6701(26)00225-2. doi: 10.1016/j.jhin.2026.05.041. Epub ahead of print. PMID: 42208740.