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Published on: July 2, 2013
The antibacterial activity of photodynamic agents against multidrug resistant bacteria causing wound infection
Ayşe Akbiyik1, Hüseyin Taşli2, Nermin Topaloğlu3
1Faculty of Health Sciences, Izmir Katip Çelebi University, Izmir Kâtip Çelebi Üniversitesi Balatçık Kampüsü, Çiğli, İzmir 35620, Turkey.
Abstract:
Antimicrobial photodynamic inactivation (aPDI) of multidrug-resistant (MDR) wound pathogens was evaluated with cationic porphyrin derivatives (CPDs). MDR bacterial strains including Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and Klebsiella pneumoniae were used. The CPDs named PM, PE, PN, and PL were synthesized as a photosensitizer (PS). A diode laser with a wavelength of 655 nm was used as a light source. aPDI of the combinations formed with different energy densities (50, 100, and 150 J/cm²) and PS concentrations (ranging from 3.125 to 600 µM) were evaluated on each bacterial strain. Dark toxicity, cytotoxicity, and phototoxicity were determined on fibroblast cells. In the aPDI groups, survival reductions of up to 5.80 log₁₀ for E. coli, 5.90 log₁₀ for P. aeruginosa, 6.11 log₁₀ for K. pneumoniae, and 6.78 log₁₀ for A. baumannii were obtained. The cytotoxic effect of PL and PM on fibroblast cells was very limited. PN was the type of CPD with the highest dark toxicity on fibroblast cells. In terms of providing broad-spectrum aPDI without or with very limited cytotoxic effect, the best result was observed in aPDI application with PL. The other CPDs need some modifications to show bacterial selectivity for use at 50 µM and above.
Insights
Cationic porphyrin derivatives (CPDs) show promise for antimicrobial photodynamic inactivation (aPDI) against multidrug-resistant wound pathogens. The CPD PL demonstrated effective bacterial reduction with minimal cytotoxicity, offering a potential new therapeutic strategy.
Area of Science:
- Photochemistry
- Microbiology
- Materials Science
Background:
- Multidrug-resistant (MDR) pathogens pose a significant threat to wound healing.
- Antimicrobial photodynamic inactivation (aPDI) offers a light-based approach to combat resistant bacteria.
Purpose of the Study:
- To evaluate the efficacy of novel cationic porphyrin derivatives (CPDs) as photosensitizers for aPDI against MDR wound pathogens.
- To assess the phototoxicity, dark toxicity, and cytotoxicity of these CPDs on fibroblast cells.
Main Methods:
- Four CPDs (PM, PE, PN, PL) were synthesized and tested as photosensitizers.
- aPDI was performed using a 655 nm diode laser at various energy densities and concentrations.
- Bacterial inactivation was quantified for Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and Klebsiella pneumoniae.
- Cytotoxicity and phototoxicity were evaluated on fibroblast cells.
Main Results:
- Significant bacterial reductions were achieved, up to 6.78 log₁₀ for A. baumannii.
- CPD PL exhibited potent antimicrobial activity with very limited cytotoxicity to fibroblast cells.
- CPD PN showed the highest dark toxicity on fibroblast cells, while PL and PM had minimal cytotoxic effects.
Conclusions:
- CPD PL is a promising candidate for broad-spectrum aPDI of MDR wound pathogens due to its efficacy and low cytotoxicity.
- Further modifications may be needed for other CPDs to enhance bacterial selectivity at higher concentrations.
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