Rapid Control of Wound Infections by Targeted Photodynamic Therapy Monitored by In Vivo Bioluminescence Imaging¶

Abstract

The worldwide rise in antibiotic resistance necessitates the development of novel antimicrobial strategies. In this study we report on the first use of a photochemical approach to destroy bacteria infecting a wound in an animal model. Following topical application, a targeted polycationic photosensitizer conjugate between poly-L-lysine and chlorin(e6) penetrated the gram (-) outer bacterial membrane, and subsequent activation with 660 nm laser light rapidly killed Escherichia coli infecting excisional wounds in mice. To facilitate real-time monitoring of infection, we used bacteria that expressed the lux operon from Photorhabdus luminescens; these cells emitted a bioluminescent signal that allowed the infection to be rapidly quantified, using a low-light imaging system. There was a light-dose dependent loss of luminescence in the wound treated with conjugate and light, not seen in untreated wounds. Treated wounds healed as well as control wounds, showing that the photodynamic treatment did not damage the host tissue. Our study points to the possible use of this methodology in the rapid control of wounds and other localized infections.

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.…”

New Approaches to Photodynamic Therapy from Types I, II and III to Type IV Using One or More Photons

“…Bacterial strains that show resistance to multiple antibiotics are effectively killed by PDT and are less prone to develop resistances [12,156,157]. Hamblin and co-workers reported the first proof-of-principle study using PDT to treat bacterially infected wound sites in mice by topically applying a poly-L-lysine and chlorin e6 conjugate to the target site, which was activated with 660 nm laser light.…”

“…Hamblin and co-workers reported the first proof-of-principle study using PDT to treat bacterially infected wound sites in mice by topically applying a poly-L-lysine and chlorin e6 conjugate to the target site, which was activated with 660 nm laser light. It was shown that Escherichia coli bacteria responsible for infecting the wounds were rapidly killed by the treatment without harming healthy tissue in the mice [157]. This was followed by studies on other microorganisms such as Staphylococcus aureus and Candida albicans and using additional PSs such as rose Bengal, toluidine blueO and methylene blue.…”

Photonic real-time monitoring of bacterial reduction in root canals by genetically engineered bacteria after chemomechanical endodontic therapy

“…After 72 h, bioluminescence imaging of each tooth inside its transparent microcentrifuge tube was carried out with a low-light intensified camera (Hamamatsu Photonics KK, Bridgewater, NJ, USA). The use of this imaging system has been described in detail in a previous work (10). Briefly, bioluminescence signal was accumulated for 2 min at 35 sensitivity level and a maximum setting on the image intensifier control module.…”

“…Research groups have employed bioluminescent imaging as a convenient means to monitor the effectiveness of antisepsis in animal models of infections caused by several bioluminescent pathogens (9). This methodology has been demonstrated in mouse models of infected wounds (10,11), burns (12), abscesses (14), and in dentistry, for endodontic treatment (14) using both Gram-positive and Gram-negative bacteria.…”