Gene expression profiling of fimA gene encoding fimbriae among clinical isolates of Porphyromonas gingivalis in response to photo-activated disinfection therapy.

Background: The endodontic disinfection therapy majorly aims to eradicate microbial pathogens. Photo-activated disinfection (PAD), also known as antimicrobial photodynamic therapy, is an alternative antimicrobial modality used to control the microorganisms causing endodontic infections. Notably, microorganisms may be exposed to sub-lethal doses of PAD (sPAD), influencing microbial virulence. The present study assessed the effects of sPAD on expression profiling of the gene associated with the biofilm formation being the most essential virulence factor in Porphyromonas gingivalis strain cells that survive the photodynamic reatment in vivo.
Materialas and Methods: Sixteen clinical strains of PAD resistant P. gingivalis that were isolated in vivo, were further photosensitized in vitro with toluidine blue O (TBO), methylene blue (MB), and indocyanine green (ICG) as the photosensitizing agents, which were excited with specific wavelength of light based on the photosensitizer. After evaluating sPAD, its effects on the fimA gene expression were assessed using real-time quantitative reverse transcription PCR (qRT-PCR).
Results: In this study, maximum values of sPAD against P. gingivalis were 6.25μg/mL TBO at a fluency of 171.87J/cm ² , 15.6μg/mL ICG at fluency of 15.6J/cm ² , and 25μg/mL MB at fluency of 93.75J/cm ² . MB-, TBO-, and ICG-sPAD could cause about 4.6-, 14.4-, and 17.3-fold suppression of fimA expression, respectively. P. gingivalis strains expressed less virulence in cells surviving PAD.
Conclusions: In conclusion, the gene expression profiling was reduced in the bacterial cells, wherein greater reduction was observed for ICG-sPAD than TBO- and MB-sPAD.
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