Diverse outcomes of Photodynamic Antimicrobial Chemotherapy on five Enterococcus faecalis strains.
OBJECTIVE
In the present study, the effectiveness of Photodynamic Antimicrobial Chemotherapy (PACT) was evaluated on planktonic cells and biofilms of five Enterococcus faecalis clinical isolates.


METHODS
Planktonic cells and biofilms of E. faecalis E2, E3, ER3/2s, OS16 and AA-OR34 were grown in SDMY medium plus 0.4% glucose. Approximately 5.0×10(7)CFU planktonic cells and 24h biofilms were subjected to PACT using the combination of Light Emitting Diodes (LEDs, Biotable(®)) and Photogem(®). The metabolic activity of bacterial cells was evaluated by a resazurin assay. Biomass values of the biofilms were determined by a crystal violet assay.


RESULTS
Compared to the water-treated control group, gradual increases of light energy led to greater reduction of metabolic activity of planktonic cells and biofilms of E. faecalis when the combination of LEDs and Photogem(®) was applied. Photogem(®) alone significantly reduced the metabolic activity of planktonic cells, whereas LEDs or Photogem(®) alone did not result in biofilm viability changes. PACT yielded similar antimicrobial outcomes on planktonic cells of all tested E. faecalis strains, whereas biofilms of E. faecalis E3, ER3/2s and OS16 were more resistant to PACT than biofilms of E. faecalis E2 and AA-OR34.


CONCLUSIONS
The efficacy of PACT on E. faecalis biofilms was strain dependent. PACT demonstrated its potential as an adjuvant antimicrobial treatment by killing of E. faecalis planktonic and biofilm cells.
Department of Pediatric Dentistry, Orthodontics and Public Health, Bauru School of Dentistry, University of São Paulo, Al. Dr. Octávio Pinheiro Brisolla, 9-75, Vila Universitária, 17012-901 Bauru, SP, Brazil. Electronic address: thiagocruvinel@fob.usp.br.
T C
TC
Silva
Department of Speech Language Pathology and Audiology, Bauru School of Dentistry, University of São Paulo, Al. Dr. Octávio Pinheiro Brisolla, 9-75, Vila Universitária, 17012-901 Bauru, SP, Brazil. Electronic address: agnes_fatima@yahoo.com.br.
A F F
AF
Pereira
Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Al. Dr. Octávio Pinheiro Brisolla, 9-75, Vila Universitária, 17012-901 Bauru, SP, Brazil. Electronic address: mbuzalaf@fob.usp.br.
M A R
MA
Buzalaf
Department of Pediatric Dentistry, Orthodontics and Public Health, Bauru School of Dentistry, University of São Paulo, Al. Dr. Octávio Pinheiro Brisolla, 9-75, Vila Universitária, 17012-901 Bauru, SP, Brazil. Electronic address: mmachado@fob.usp.br.
M A A M
MA
Machado
Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Gustav Mahler Laan, 3004, 1081 Amsterdam, The Netherlands. Electronic address: W.Crielaard@acta.nl.
W
W
Crielaard
Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Gustav Mahler Laan, 3004, 1081 Amsterdam, The Netherlands. Electronic address: d.deng@acta.nl.
D M
DM
Deng
D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development* / Q000528:radiation effects; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D013293:Enterococcus faecalis / Q000145:classification / Q000187:drug effects* / Q000502:physiology*; D006415:Hematoporphyrins / Q000008:administration & dosage*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D010933:Plankton / Q000187:drug effects / Q000502:physiology*; D013045:Species Specificity
D000900:Anti-Bacterial Agents; D006415:Hematoporphyrins; D017319:Photosensitizing Agents
Biofilm; Enterococcus faecalis; Light Emitting Diode; Photodynamic Antimicrobial Chemotherapy; Planktonic cells