Hypochlorous acid demonstrates antibiofilm activity with preserved cellular morphology in an in-vitro comparison with ciprofloxacin and ethanol.

BACKGROUND

Catheter-related bloodstream infections remain a clinical challenge due to intraluminal biofilm formation. Conventional antibiotic and ethanol lock therapies are limited by antimicrobial resistance, incomplete penetration, and cytotoxicity. Stabilized hypochlorous acid (HOCl), a potent oxidant with antimicrobial properties, has emerged as a potential alternative; however, its stabilized formulation differs from transient neutrophil-derived HOCl.

OBJECTIVE

The aim of this study was to evaluate the antibiofilm efficacy and cytotoxic profile of HOCl compared with 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, while ciprofloxacin was used at 500× minimum inhibitory concentration 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 with 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

Stabilized 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.