Eradication of Staphylococcus aureus Catheter-Related Biofilm Infections Using ML:8 and Citrox

Antimicrob Agents Chemother. 2016 Sep 23;60(10):5968-75. doi: 10.1128/AAC.00910-16. Print 2016 Oct.


Staphylococci are a leading cause of catheter-related infections (CRIs) due to biofilm formation. CRIs are typically managed by either device removal or systemic antibiotics, often in combination with catheter lock solutions (CLSs). CLSs provide high concentrations of the antimicrobial agent at the site of infection. However, the most effective CLSs against staphylococcal biofilm-associated infections have yet to be determined. The purpose of this study was to evaluate the efficacy and suitability of two newly described antimicrobial agents, ML:8 and Citrox, as CLSs against Staphylococcus aureus biofilms. ML:8 (1% [vol/vol]) and Citrox (1% [vol/vol]), containing caprylic acid and flavonoids, respectively, were used to treat S. aureus biofilms grown in vitro using newly described static and flow biofilm assays. Both agents reduced biofilm viability >97% after 24 h of treatment. Using a rat model of CRI, ML:8 was shown to inactivate early-stage S. aureus biofilms in vivo, while Citrox inactivated established, mature in vivo biofilms. Cytotoxicity and hemolytic activity of ML:8 and Citrox were equivalent to those of other commercially available CLSs. Neither ML:8 nor Citrox induced a cytokine response in human whole blood, and exposure of S. aureus to either agent for 90 days was not associated with any increase in resistance. Taken together, these data reveal the therapeutic potential of these agents for the treatment of S. aureus catheter-related biofilm infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Biofilms / drug effects
  • Caprylates / pharmacology*
  • Catheter-Related Infections / drug therapy*
  • Drug Evaluation, Preclinical / methods
  • Flavonoids / pharmacology*
  • Humans
  • Male
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Methicillin-Resistant Staphylococcus aureus / pathogenicity
  • Rats, Sprague-Dawley
  • Staphylococcal Infections / drug therapy*
  • Staphylococcus aureus / drug effects*
  • Staphylococcus aureus / pathogenicity


  • Anti-Bacterial Agents
  • Caprylates
  • Flavonoids
  • octanoic acid

Grant support

This work, including the efforts of Hilary Humphreys, James P. O'Gara, and Eoghan O’Neill, was funded by Health Research Board (HRB) (HRA_POR/2012/52) and by Healthcare Infection Society (HIS) (HIS Major Award 2011). The funders had no role in the design, execution, or interpretation of this study and were not involved in the decision to submit the work for publication.