Enwemeka Chukuka S, Williams Deborah, Enwemeka Sombiri K, Hollosi Steve, Yens David
School of Health Professions, Behavioral, and Life Sciences, New York Institute of Technology, Old Westbury, New York 11568-8000, USA.
Photomed Laser Surg. 2009 Apr;27(2):221-6. doi: 10.1089/pho.2008.2413.
In a previous study, we showed that 405-nm light photo-destroys methicillin-resistant Staphylococcus aureus (MRSA). The 390-420 nm spectral width of the 405-nm superluminous diode (SLD) source may raise safety concerns in clinical practice, because of the trace of ultraviolet (UV) light within the spectrum.
Here we report the effect of a different wavelength of blue light, one that has no trace of UV, on two strains of MRSA--the US-300 strain of CA-MRSA and the IS-853 strain of HA-MRSA--in vitro.
We cultured and plated each strain, and then irradiated each plate with 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 25, 30, 35, 40, 45, 50, 55, or 60 J/cm2 of energy a single time, using a 470-nm SLD phototherapy device. The irradiated specimens were then incubated at 35 degrees C for 24 h. Subsequently, digital images were made and quantified to obtain colony counts and the aggregate area occupied by bacteria.
Photo-irradiation produced a statistically significant dose-dependent reduction in both the number and the aggregate area of colonies formed by each strain (p < 0.001). The higher the dose the more bacteria were killed, but the effect was not linear, and was more impressive at lower doses than at higher doses. Nearly 30% of both strains was killed with as little as 3 J/cm2 of energy. As much as 90.4% of the US-300 and the IS-853 colonies, respectively, were killed with an energy density of 55 J/cm2. This same dose eradicated 91.7% and 94.8% of the aggregate area of the US-300 and the IS-853 strains, respectively.
At practical dose ranges, 470-nm blue light kills HA-MRSA and CA-MRSA in vitro, suggesting that a similar bactericidal effect may be attained in human cases of cutaneous and subcutaneous MRSA infections.
在之前的一项研究中，我们发现405纳米的光可光破坏耐甲氧西林金黄色葡萄球菌（MRSA）。405纳米超发光二极管（SLD）光源390 - 420纳米的光谱宽度可能会在临床实践中引发安全担忧，因为光谱内存在微量紫外线（UV）。
在此我们报告一种不同波长的蓝光（无紫外线痕迹）对两种MRSA菌株——社区获得性MRSA的US - 300菌株和医院获得性MRSA的IS - 853菌株——的体外作用。
我们培养并接种每种菌株，然后使用470纳米的SLD光疗设备，以0、1、3、5、7、9、11、13、15、17、19、25、30、35、40、45、50、55或60 J/cm²的能量对每个平板进行单次照射。然后将照射后的标本在35摄氏度下孵育24小时。随后，拍摄数码图像并进行定量分析，以获得菌落计数和细菌占据的总面积。
光照射使每种菌株形成的菌落数量和总面积均产生具有统计学意义的剂量依赖性减少（p < 0.001）。剂量越高，杀死的细菌越多，但这种效应并非线性，且在较低剂量时比在较高剂量时更显著。仅3 J/cm²的能量就能杀死近30%的两种菌株。能量密度为55 J/cm²时，分别有多达90.4%的US - 300和IS - 853菌落被杀死。相同剂量分别消除了US - 300和IS - 853菌株总面积的91.7%和94.8%。
在实际剂量范围内，470纳米蓝光可在体外杀死医院获得性MRSA和社区获得性MRSA，这表明在人类皮肤和皮下MRSA感染病例中可能会获得类似的杀菌效果。
