title: Blue light-mediated inactivation of Enterococcus faecalis in vitro.
abstract: In dentistry, residual infection remains a major cause of failure after endodontic treatment; many of these infections involve Enterococcus faecalis. In the current study, we explored the possibility that blue light activated photosensitizers could be used, in principle, to inactivate this microbe as an adjunct disinfection strategy for endodontic therapy. Three blue light absorbing photosensitizers, eosin-Y, rose bengal, and curcumin, were tested on E. faecalis grown in planktonic suspensions or biofilms. Photosensitizers were incubated for 30 min with bacteria then exposed to blue light (450-500 nm) for 240 s. Sodium hypochlorite (3%) was used as a control. After 48 h, the viability of E. faecalis was estimated by measuring colony-forming units post-exposure vs. untreated controls (CFU/mL). Blue light irradiation alone did not alter E. faecalis viability. For planktonic cultures, blue light activated eosin-Y (5 μM), rose bengal (1 μM), or curcumin (5 μM) significantly (p<0.05) reduced E. faecalis viability compared to exposure to the unirradiated photochemicals. For biofilm cultures, concentrations of light-activated eosin-Y, rose bengal, and curcumin of 100, 10, and 10 μM respectively, completely suppressed E. faecalis viability (p<0.05). Although the current results are limited to an in vitro model, they support further exploration of blue light activated antimicrobials as an adjunct therapy in endodontic treatment.
authors.affiliation: Endodontics Unit, Section of Dental Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Pileggi
authors.forename: John C
authors.initials: JC
authors.lastname: Wataha
authors.forename: Myriam
authors.initials: M
authors.lastname: Girard
authors.forename: Iwona
authors.initials: I
authors.lastname: Grad
authors.forename: Jacques
authors.initials: J
authors.lastname: Schrenzel
authors.forename: Norbert
authors.initials: N
authors.lastname: Lange
authors.forename: Serge
authors.initials: S
authors.lastname: Bouillaguet
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003116:Color; D003474:Curcumin / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D013293:Enterococcus faecalis / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects*; D004801:Eosine Yellowish-(YS) / Q000008:administration & dosage*; D005456:Fluorescent Dyes / Q000008:administration & dosage; D008029:Lighting / Q000379:methods*; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D012395:Rose Bengal / Q000008:administration & dosage*
chemical_list: D005456:Fluorescent Dyes; D017319:Photosensitizing Agents; D012395:Rose Bengal; D003474:Curcumin; D004801:Eosine Yellowish-(YS)