The Effect of Antimicrobial Photodynamic Therapy with Radachlorin® on Staphylococcus Aureus and Escherichia Coli: An in Vitro Study

[摘要] Introduction: The a im of this study is the evaluation of the effect of Antimicrobial Photodynamic Therapy with Radachlorin on Staphylococcus aureus and Escherichia coli. New windows are open in the antimicrobial field so-call Photodynamic therapy that incorporates a nonpoisonous photosensitizer (PS) with innocuous special wavelength photons to excite the PS. Methods: Two strains of bacteria used in this study were Methicillin resistant Staphylococcus aureus (ATCC 33591; PTCC 1764) and Escherichia coli (ATCC 25922; PTCC1399). Concentrations of 0.2 ml of Radachlorin® were applied on 0.2 ml of bacterial suspensions and placed in a 48-well microtiter plate. The following groups were used: (I) L− PS− (no laser, no photosensitizer), (II) L−PS+ (treated only with PS), (III) L+ PS− (treated only with laser) and (IV) L+ PS+ (treated with laser and PS: photodynamic therapy group). Aliquots of bacterial suspensions were sensitized with Radachlorin® for 15 minutes in the dark at room temperature and then bacterial suspensions in group III and IV were irradiated with 210 mW (power density) and 12 J/cm2 (energy density) on continuous mode. Results: This study showed that photodynamic therapy reduces 0.14 log 10 in E.Coli (group IV) and there were significant differences for group IV (P<0.01). Photodynamic therapy in S.Aureus showed 6.28 log 10 colony count reduction (group IV) and there were highly significant differences in Photodynamic therapy group (P<0.0001). Conclusion: Radachlorin® have bactericidal effect on S.aureus (6.28 log 10) and bacteriostatic effect on E.coli (0.14 log 10).

[学科分类] 基础医学

[关键词] photodynamic therapy