title: High-Velocity Microsprays Enhance Antimicrobial Activity in Streptococcus mutans Biofilms.
abstract: Streptococcus mutans in dental plaque biofilms play a role in caries development. The biofilm's complex structure enhances the resistance to antimicrobial agents by limiting the transport of active agents inside the biofilm. The authors assessed the ability of high-velocity water microsprays to enhance delivery of antimicrobials into 3-d-old S. mutans biofilms. Biofilms were exposed to a 90° or 30° impact, first using a 1-µm tracer bead solution (109beads/mL) and, second, a 0.2% chlorhexidine (CHX) or 0.085% cetylpyridinium chloride (CPC) solution. For comparison, a 30-s diffusive transport and simulated mouthwash were also performed. Confocal microscopy was used to determine number and relative bead penetration depth into the biofilm. Assessment of antimicrobial penetration was determined by calculating the killing depth detected by live/dead viability staining. The authors first demonstrated that the microspray was able to deliver significantly more microbeads deeper in the biofilm compared with diffusion and mouthwashing exposures. Next, these experiments revealed that the microspray yielded better antimicrobial penetration evidenced by deeper killing inside the biofilm and a wider killing zone around the zone of clearance than diffusion alone. Interestingly the 30° impact in the distal position delivered approximately 16 times more microbeads and yielded approximately 20% more bacteria killing (for both CHX and CPC) than the 90° impact. These data suggest that high-velocity water microsprays can be used as an effective mechanism to deliver microparticles and antimicrobials inside S. mutans biofilms. High shear stresses generated at the biofilm-burst interface might have enhanced bead and antimicrobial delivery inside the remaining biofilm by combining forced advection into the biofilm matrix and physical restructuring of the biofilm itself. Further, the impact angle has potential to be optimized both for biofilm removal and active agents' delivery inside biofilm in those protected areas where some biofilm might remain.
authors.affiliation: National Centre for Advanced Tribology at Southampton (nCATS), University of Southampton, Southampton, UK stefaniafabbri1987@gmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Fabbri
authors.affiliation: Biomedical Imaging Unit, School of Medicine, University of Southampton, Southampton, UK.
authors.forename: D A
authors.initials: DA
authors.lastname: Johnston
authors.affiliation: Philips Research, High Tech Campus, Eindhoven, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Rmaile
authors.affiliation: Philips Research, High Tech Campus, Eindhoven, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Gottenbos
authors.affiliation: Philips Research, High Tech Campus, Eindhoven, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: De Jager
authors.affiliation: Wrigley, Chicago, IL, USA.
authors.forename: M
authors.initials: M
authors.lastname: Aspiras
authors.affiliation: Philips Oral Healthcare, Bothell, Washington, USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Starke
authors.affiliation: Philips Oral Healthcare, Bothell, Washington, USA.
authors.forename: M T
authors.initials: MT
authors.lastname: Ward
authors.affiliation: National Centre for Advanced Tribology at Southampton (nCATS), University of Southampton, Southampton, UK.|Departments of Microbial Infection and Immunity and the Department of Orthopaedics, Centre for Microbial Interface Biology, The Ohio State University, Columbus, OH, USA.
authors.forename: P
authors.initials: P
authors.lastname: Stoodley
mesh_terms: D000891:Anti-Infective Agents, Local / Q000008:administration & dosage* / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development*; D002594:Cetylpyridinium / Q000008:administration & dosage* / Q000494:pharmacology*; D002710:Chlorhexidine / Q000008:administration & dosage* / Q000494:pharmacology*; D003773:Dental Plaque / Q000382:microbiology*; D066298:In Vitro Techniques; D044085:Microfluidics / Q000379:methods*; D018613:Microscopy, Confocal; D009067:Mouthwashes / Q000008:administration & dosage / Q000494:pharmacology; D013295:Streptococcus mutans / Q000187:drug effects* / Q000254:growth & development*; D014867:Water
chemical_list: D000891:Anti-Infective Agents, Local; D009067:Mouthwashes; D014867:Water; D002594:Cetylpyridinium; D002710:Chlorhexidine
keywords: antimicrobials/antimicrobial resistance; caries detection/diagnosis/prevention; dental hygiene; drug delivery; oral hygiene; plaque/plaque biofilms