Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light Plus Water-Filtered Infrared A and Tetrahydroporphyrin-tetratosylate (THPTS).

Lamprini Karygianni,Ali Al-Ahmad,Kirstin Vach,Marie Follo,Sandra Ruf,Elmar Hellwig

doi:10.3390/microorganisms9010145

Lamprini Karygianni, Ali Al-Ahmad + Show 4 more

Open Access

https://doi.org/10.3390/microorganisms9010145

Copy DOI

Journal: Microorganisms	Publication Date: Jan 11, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: University of Zurich, University of Freiburg

Abstract

The aim of this study was to examine the effect of aPDT with visual light (VIS) + water-filtered infrared A (wIRA) as a light source, and tetrahydroporphyrin-tetratosylate (THPTS) as a photosensitizer on in situ initial and mature oral biofilms. The samples were incubated, ex situ, with THPTS for two minutes, followed by irradiation with 200 mW cm − 2 VIS + wIRA for five minutes at 37 °C. The adherent microorganisms were quantified, and the biofilm samples were visualized using live/dead staining and confocal laser scanning microscopy (CLSM). The THPTS-mediated aPDT resulted in significant decreases in both the initially adherent microorganisms and the microorganisms in the mature oral biofilms, in comparison to the untreated control samples (>99.99% each; p = 0.018 and p = 0.0066, respectively). The remaining vital bacteria significantly decreased in the aPDT-treated biofilms during initial adhesion (vitality rate 9.4% vs. 71.2% untreated control, 17.28% CHX). Of the mature biofilms, 25.67% remained vital after aPDT treatment (81.97% untreated control, 16.44% CHX). High permeability of THPTS into deep layers could be shown. The present results indicate that the microbial reduction in oral initial and mature oral biofilms resulting from aPDT with VIS + wIRA in combination with THPTS has significant potential for the treatment of oral biofilm-associated diseases.

Highlights

Photodynamic therapy (PDT), a method which involves combining non-toxic, photosensitizing dyes with a light source, is becoming increasingly more important due to the emergence of multi-drug resistance in pathogenic bacteria, and due to the enhanced resistance of bacteria located in biofilms
We evaluated the photodynamic efficacy of tetrahydroporphyrintetratosylate (THPTS) on initial oral bacterial adhesion and mature oral biofilm, by using visible light plus waterfiltered infrared A (wIRA) (VIS+wIRA) as the light source
The THPTS-mediated Antimicrobial PDT (aPDT) resulted in a significant decrease, of more than 99.99%, in the viable microbial counts after two hours

Summary

Introduction

Photodynamic therapy (PDT), a method which involves combining non-toxic, photosensitizing dyes with a light source, is becoming increasingly more important due to the emergence of multi-drug resistance in pathogenic bacteria, and due to the enhanced resistance of bacteria located in biofilms. Antimicrobial PDT (aPDT) as an alternative approach or adjunct method of dental bacterial decontamination, has the advantage that it can be applied locally because the photosensitizer is favorably located in the bacteria and not in the surrounding tissue [2]. This therapy does not induce any resistance [1].

Objectives

Methods

Results

Discussion

Conclusion