Laser Institute for Research and Applications LIRA, Beni-Suef University, Beni-Suef, 62511, Egypt.
Department of Microbiology and Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, 62514, Egypt.
Lasers Med Sci. 2024 May 29;39(1):144. doi: 10.1007/s10103-024-04080-5.
Enterococcus faecalis is among the most resistant bacteria found in infected root canals. The demand for cutting-edge disinfection methods has rekindled research on photoinactivation with visible light. This study investigated the bactericidal activity of femtosecond laser irradiation against vancomycin-resistant Enterococcus faecalis V583 (VRE). The effect of parameters such as wavelength and energy density on the viability and growth kinetics of VRE was studied to design an optimized laser-based antimicrobial photoinactivation approach without any prior addition of exogenous photosensitizers. The most effective wavelengths were 430 nm and 435 nm at a fluence of 1000 J/cm, causing a nearly 2-log reduction (98.6% and 98.3% inhibition, respectively) in viable bacterial counts. The colony-forming units and growth rate of the laser-treated cultures were progressively decreased as energy density or light dose increased at 445 nm but reached a limit at 1250 J/cm. At a higher fluence of 2000 J/cm, the efficacy was reduced due to a photobleaching phenomenon. Our results highlight the importance of optimizing laser exposure parameters, such as wavelength and fluence, in bacterial photoinactivation experiments. To our knowledge, this is the first study to report an optimized wavelength for the inactivation of VRE using visible femtosecond laser light.
粪肠球菌是感染根管中最具耐药性的细菌之一。对先进消毒方法的需求重新点燃了可见光光灭活研究的热情。本研究调查了飞秒激光照射对万古霉素耐药粪肠球菌 V583（VRE）的杀菌活性。研究了波长和能量密度等参数对 VRE 活力和生长动力学的影响，旨在设计一种无需预先添加外源性光敏剂的优化基于激光的抗菌光灭活方法。最有效的波长是 430nm 和 435nm，在 1000J/cm 的辐照度下，活菌计数分别减少近 2 个对数（分别为 98.6%和 98.3%的抑制）。在 445nm 时，随着能量密度或光剂量的增加，激光处理培养物的菌落形成单位和生长速率逐渐降低，但在 1250J/cm 时达到极限。在更高的 2000J/cm 辐照度下，由于光漂白现象，功效降低。我们的结果强调了在细菌光灭活实验中优化激光暴露参数（如波长和辐照度）的重要性。据我们所知，这是第一项使用可见光飞秒激光报告优化 VRE 灭活波长的研究。
