Role of efflux pump inhibitors on the antibiofilm efficacy of calcium hydroxide, chitosan nanoparticles, and light-activated disinfection

Abstract

Introduction: The purpose of this study was to evaluate the role of efflux pumps in altering the susceptibility of Enterococcus faecalis biofilms to calcium hydroxide (Ca(OH) 2), chitosan nanoparticles, and light-activated disinfection (LAD). Methods: E. faecalis as 4-day-old biofilms and biofilm-derived cells were tested with aqueous Ca(OH) 2 in concentrations of 25%, 50%, and 100%; chitosan nanoparticles in concentrations of 10 and 20 mg/mL (3, 12, and 24 hours); and methylene blue (MB) mediated LAD at an energy dose range of 2-40 J/cm 2. An efflux pump inhibitor (EPI) was incorporated into all 3 modalities of treatment. The antimicrobial activity was assessed by determining the colony-forming units. Results: E. faecalis biofilms, in contrast to the biofilm-derived cells, were found to persist even after 24-hour treatment with different concentrations of Ca(OH) 2 and chitosan nanoparticles. LAD at an energy dose of 40 J/cm 2 completely inactivated 4-day-old E. faecalis biofilms. The addition of EPI improved the antibiofilm efficacy of Ca(OH) 2 at lower concentrations (P