In Vitro and In Vivo Antimicrobial Activity of Hypochlorous Acid against Drug-Resistant and Biofilm-Producing Strains

Microbiol Spectr. 2022 Oct 26;10(5):e0236522. doi: 10.1128/spectrum.02365-22. Epub 2022 Oct 3.


The aims of this study were as follows. First, we determined the antimicrobial efficacy of hypochlorous acid (HClO) against bacterial, fungal, and yeast strains growing planktonically and growing in biofilms. Second, we sought to compare the activity of the combination of daptomycin and HClO versus those of the antimicrobial agents alone for the treatment of experimental catheter-related Staphylococcus epidermidis infection (CRI) using the antibiotic lock technique (ALT) in a rabbit model. HClO was generated through direct electric current (DC) shots at determined amperages and times. For planktonic susceptibility studies, 1 to 3 DC shots of 2, 5, and 10 mA from 0 to 300 s were applied. A DC shot of 20 mA from 0 to 20 min was applied to biofilm-producing strains. Central venous catheters were inserted into New Zealand White rabbits, inoculated with an S. epidermidis strain, and treated with saline solution or ALT using daptomycin (50 mg/mL), HClO (20 mA for 45 min), or daptomycin plus HClO. One hundred percent of the planktonic bacterial, fungal, and yeast strains were killed by applying one DC shot of 2, 5, and 10 mA, respectively. One DC shot of 20 mA for 20 min was sufficient to eradicate 100% of the tested biofilm-producing strains. Daptomycin plus HClO lock therapy showed the highest activity for experimental CRI with S. epidermidis. HClO could be an effective strategy for treating infections caused by extensively drug-resistant or multidrug-resistant and biofilm-producing strains in medical devices and chronic wounds. The results of the ALT using daptomycin plus HClO may be promising. IMPORTANCE Currently, drug-resistant infections are increasing and there are fewer antibiotics available to treat them. Therefore, there is an urgent need to find new antibiotics and nonantimicrobial strategies to treat these infections. We present a new nonantibiotic strategy based on hypochlorous acid generation to treat long-term catheter-related and chronic wounds infections.

Keywords: A. fumigatus; Candida spp.; HClO; MDR bacteria; XDR bacteria; antibiotic lock technique; biofilms; catheter-related infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Anti-Infective Agents* / pharmacology
  • Biofilms
  • Catheter-Related Infections* / drug therapy
  • Catheter-Related Infections* / microbiology
  • Daptomycin* / pharmacology
  • Hypochlorous Acid / pharmacology
  • Microbial Sensitivity Tests
  • Rabbits
  • Saccharomyces cerevisiae
  • Saline Solution / pharmacology
  • Staphylococcus epidermidis
  • Vancomycin / pharmacology


  • Daptomycin
  • Vancomycin
  • Hypochlorous Acid
  • Saline Solution
  • Anti-Bacterial Agents
  • Anti-Infective Agents