Energy dose parameters affect antimicrobial photodynamic therapy-mediated eradication of periopathogenic biofilm and planktonic cultures

This study evaluated the in vitro efficacy of a commercially available aPDT system in eradication of the periopathogens Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans in both planktonic and biofilm cultures. Antimicrobial photodynamic therapy (aPDT) is a...

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Bibliographic Details
Published in:	Photomedicine and laser surgery Vol. 28 Suppl 1; p. S61
Main Authors:	Street, Cale N, Pedigo, Lisa A, Loebel, Nicolas G
Format:	Journal Article
Language:	English
Published:	United States 01-08-2010
Subjects:	Aggregatibacter actinomycetemcomitans - drug effects Aggregatibacter actinomycetemcomitans - radiation effects Biofilms Cells, Cultured Dose-Response Relationship, Radiation Fusobacterium nucleatum - drug effects Fusobacterium nucleatum - radiation effects Gram-Negative Bacteria - drug effects Gram-Negative Bacteria - radiation effects Gram-Negative Bacterial Infections - drug therapy Gram-Negative Bacterial Infections - radiotherapy Photochemotherapy Plankton - radiation effects Porphyromonas gingivalis - drug effects Porphyromonas gingivalis - radiation effects Temperature
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Summary:	This study evaluated the in vitro efficacy of a commercially available aPDT system in eradication of the periopathogens Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans in both planktonic and biofilm cultures. Antimicrobial photodynamic therapy (aPDT) is an effective antibacterial approach in vitro; however, few data are available regarding effective light-energy parameters. Planktonic and biofilm cultures of periopathogens were exposed to a methylene blue-based formulation and irradiated with a 670-nm nonthermal diode laser. Energy doses were varied from 2.3 to 9.4 J/cm(2) through adjustments in illumination time and a constant power density. Controls consisted of no treatment, light only, and photosensitizer only. Temperature changes were recorded in experimental samples before and after illumination. aPDT with an energy dose of 9.4 J/cm(2) was effective in eradicating P. gingivalis, F. nucleatum, and A. actinomycetemcomitans in biofilm and planktonic form. Reductions from control in planktonic cultures at this energy dose were 6.8 +/- 0.7, 5.2 +/- 0.6, and 1.9 +/- 0.6 log(10), respectively, whereas biofilm reductions were 4.5 +/- 1.2, 3.4 +/- 1.1, and 4.9 +/- 1.4 log(10). Decreasing the treatment time produced an energy dose-dependent killing effect in both models. Changes in sample temperature did not exceed 3 degrees C under these exposure parameters. This study demonstrated that three important periopathogens are susceptible to aPDT-mediated killing, regardless of whether they are present in planktonic or biofilm form. Furthermore, a clear energy dose-dependence exists with this treatment that should to be taken into account when determining optimal treatment times in clinical application.
ISSN:	1557-8550
DOI:	10.1089/pho.2009.2622