Photodynamic therapy for Staphylococcus aureus infected burn wounds in mice

Abstract

The rise of multiply antibiotic resistant bacteria has led to searches for novel antimicrobial therapies to treat infections. Photodynamic therapy (PDT) is a potential candidate; it uses the combination of a photosensitizer with visible light to produce reactive oxygen species that lead to cell death. We used PDT mediated by meso-mono-phenyl-tri(N-methyl-4-pyridyl)-porphyrin (PTMPP) to treat burn wounds in mice with established Staphylococcus aureus infections The third degree burn wounds were infected with bioluminescent S. aureus. PDT was applied after one day of bacterial growth by adding a 25% DMSO/500 microM PTMPP solution to the wound followed by illumination with red light and periodic imaging of the mice using a sensitive camera to detect the bioluminescence. More than 98% of the bacteria were eradicated after a light dose of 210 J cm(-2) in the presence of PTMPP. However, bacterial re-growth was observed. Light alone or PDT both delayed the wound healing. These data suggest that PDT has the potential to rapidly reduce the bacterial load in infected burns. The treatment needs to be optimized to reduce wound damage and prevent recurrence.

Photodynamic antimicrobial therapy

“…The influence of PACT on infected wounds, burns, infection of soft tissues, disorders caused by Helicobacter pylori, and brain abscess have been evaluated. Application of PS and local irradiation in mice showed a significant reduction of bacteria infected wounds and burns, better healing of wounds and no sepsis developed [43,44]. In a study on rats, it was possible to eradicate Porphyromonas gingivalis in the periodontal pockets surrounding the affected tooth by using PACT (toluidine blue as a photosensitive substance).…”

Antimicrobial photodynamic therapy combined with conventional endodontic treatment to eliminate root canal biofilm infection

“…Our laboratory has employed bioluminescent imaging as a convenient means to monitor the effectiveness of antimicrobial PDT in animal models of infections caused by several bioluminescent pathogens [38]. This methodology has been demonstrated in mouse models of infected wounds [39,40] burns [41] and abscesses [42] using both Gram-positive and Gram-negative bacteria.…”

Chemiluminescence as a PDT light source for microbial control

“…It is clear that a higher microorganism reduction can be obtained with the much higher light intensities achieved with laser or LED sources, as presented by studies where the log decrease is of 4-6 units [2,29,33]. We believe that this log reduction range is difficult to obtain using the chemiluminescence as a light source.…”

“…The microbial control and bacterial reduction studies became objects of great interest to public health, especially when these microorganisms have been related to hospital infection, as the Staphylococcus aureus [3,7,[23][24][25][26][27][28][29][30]. Therefore, the development of techniques for microbial control that are not antibiotic dependent became very important [31,32] as shown by Meisel, Zeina, O'riodan and Hasan where they verified that an infection control using different types of photosensitizers (methylene blue, rose bengal, chlorophyll, phthalocyanines and others) were effective on both Gram negative and Gram positive microorganisms, e.g.…”