Medical-Grade Silicone Coated with Rhamnolipid R89 Is Effective against Staphylococcus spp. Biofilms

Molecules. 2019 Oct 25;24(21):3843. doi: 10.3390/molecules24213843.

Abstract

Staphylococcus aureus and Staphylococcus epidermidis are considered two of the most important pathogens, and their biofilms frequently cause device-associated infections. Microbial biosurfactants recently emerged as a new generation of anti-adhesive and anti-biofilm agents for coating implantable devices to preserve biocompatibility. In this study, R89 biosurfactant (R89BS) was evaluated as an anti-biofilm coating on medical-grade silicone. R89BS is composed of homologues of the mono- (75%) and di-rhamnolipid (25%) families, as evidenced by mass spectrometry analysis. The antimicrobial activity against Staphylococcus spp. planktonic and sessile cells was evaluated by microdilution and metabolic activity assays. R89BS inhibited S. aureus and S. epidermidis growth with minimal inhibitory concentrations (MIC99) of 0.06 and 0.12 mg/mL, respectively and dispersed their pre-formed biofilms up to 93%. Silicone elastomeric discs (SEDs) coated by R89BS simple adsorption significantly counteracted Staphylococcus spp. biofilm formation, in terms of both built-up biomass (up to 60% inhibition at 72 h) and cell metabolic activity (up to 68% inhibition at 72 h). SEM analysis revealed significant inhibition of the amount of biofilm-covered surface. No cytotoxic effect on eukaryotic cells was detected at concentrations up to 0.2 mg/mL. R89BS-coated SEDs satisfy biocompatibility requirements for leaching products. Results indicate that rhamnolipid coatings are effective anti-biofilm treatments and represent a promising strategy for the prevention of infection associated with implantable devices.

Keywords: Staphylococcus spp.; anti-adhesive; anti-biofilm; antimicrobial; biofilm; biomaterials; biosurfactants; medical devices; silicone.

MeSH terms

  • Biofilms / drug effects*
  • Coated Materials, Biocompatible / chemistry
  • Coated Materials, Biocompatible / pharmacology
  • Humans
  • Microbial Sensitivity Tests
  • Prostheses and Implants / adverse effects
  • Prostheses and Implants / microbiology
  • Prosthesis-Related Infections / drug therapy*
  • Prosthesis-Related Infections / microbiology
  • Silicone Elastomers / chemistry
  • Silicone Elastomers / pharmacology
  • Silicones / chemistry
  • Silicones / pharmacology
  • Staphylococcal Infections / drug therapy*
  • Staphylococcal Infections / microbiology
  • Staphylococcal Infections / pathology
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / pathogenicity
  • Staphylococcus epidermidis / pathogenicity
  • Surface-Active Agents / chemistry
  • Surface-Active Agents / pharmacology*

Substances

  • Coated Materials, Biocompatible
  • Silicone Elastomers
  • Silicones
  • Surface-Active Agents