[P2-2-24] Effect of 5-aminolevulinic acid phosphate mediated photodynamic therapy on Fusobacterium nucleatum subspecies
キーワード：Fusobacterium nucleatum、5-aminolevulinic acid、Photodynamic therapy
Photodynamic therapy (PDT) is a minimally invasive therapy that combines a photosensitizer with light of specific wavelengths to inactivate microorganisms without creating antimicrobial resistance. Porphyrin-type photosensitizers activated by red light (635 nm) are produced by the metabolism of 5-aminolevulinic acid (5-ALA) in bacterial cells. Fusobacterium nucleatum is a Gram-negative anaerobic rod ubiquitous to the oral cavity and has been associated not only with periodontitis but also with colon cancer and systemic diseases. F. nucleatum has four subspecies: animalis, nucleatum, polymorphum, and vincentii, each of which has been reported to differ in virulence and biofilm-forming ability. We have previously shown that 5-ALA phosphate mediated photodynamic therapy (ALA-PDT) efficiently inactivates F. nucleatum. In this study, we investigated the bactericidal effect of ALA-PDT on each F. nucleatum subspecies. The results showed that ALA-PDT significantly reduced CFU counts for all subspecies of F. nucleatum, but not for F. periodonticum. Differences in the bactericidal effect of ALA-PDT were observed among the four subspecies of F. nucleatum, and the effect was correlated with the concentration of porphyrins produced by each subspecies. It is suggested that the efficient induction of porphyrins production may increase the bactericidal effect of ALA-PDT in F. nucleatum.