光谱分辨红外显微镜和化学计量工具揭示蓝光（470nm）与耐甲氧西林金黄色葡萄球菌的相互作用。
Spectrally resolved infrared microscopy and chemometric tools to reveal the interaction between blue light (470nm) and methicillin-resistant Staphylococcus aureus.
机构信息
Department of Biomedical Sciences, University of Wisconsin- Milwaukee, Milwaukee, USA.
Physics Department, University of Wisconsin-Milwaukee, Milwaukee, USA.
出版信息
J Photochem Photobiol B. 2017 Feb;167:150-157. doi: 10.1016/j.jphotobiol.2016.12.030. Epub 2016 Dec 23.
Blue light inactivates methicillin-resistant Staphylococcus aureus (MRSA), a Gram-positive antibiotic resistant bacterium that leads to fatal infections; however, the mechanism of bacterial death remains unclear. In this paper, to uncover the mechanism underlying the bactericidal effect of blue light, a combination of Fourier transform infrared (FTIR) spectroscopy and chemometric tools is employed to detect the photoreactivity of MRSA and its distinctive pathway toward apoptosis after treatment. The mechanism of action of UV light and vancomycin against MRSA is also investigated to support the findings. Principal component analysis followed by linear discriminant analysis (PCA- LDA) is employed to reveal clustering of five groups of MRSA samples, namely untreated (control I), untreated and incubated at ambient air (control II), irradiated with 470nm blue light, irradiated with 253.5 UV light, and vancomycin-treated MRSA. Loadings plot from PCA-LDA analysis reveals important functional groups in proteins (1683, 1656, 1596, 1542cm), lipids (1743, 1409cm), and nucleic acids region of the spectrum (1060, 1087cm) that are responsible for the classification of blue light irradiated spectra and control spectra. Cluster vector plots and scores plot reveals that UV light-irradiated spectra are the most biochemically similar to blue light- irradiated spectra; however, some wavenumbers experience a shift. The shifts between blue light and UV light irradiated loadings plot at ν PO band (from 1228 to 1238cm), DNA backbone (from 970 to 966cm) and base pairing vibration of DNA (from 1717 to 1712cm) suggest distinctive changes in DNA conformation in response to irradiation. Our findings indicate that irradiation of MRSA with 470nm light induces A-DNA cleavage and that B-DNA is more resistant to damage by blue light. Blue light and UV light treatment of MRSA are complementary and distinct from the known antimicrobial effect of vancomycin. Moreover, it is known that UV-induced cleavage of DNA predominantly targets B-DNA, which is in agreement with the FTIR findings. Overall the results suggest that the combination of light and vancomycin could be a more robust approach in treating MRSA infections.
蓝光可使耐甲氧西林金黄色葡萄球菌（MRSA）失活，MRSA 是一种革兰氏阳性抗生素耐药菌，可导致致命感染；然而，细菌死亡的机制仍不清楚。在本文中，为了揭示蓝光杀菌作用的机制，采用傅里叶变换红外（FTIR）光谱和化学计量工具相结合的方法，检测了 MRSA 的光反应性及其在处理后的凋亡独特途径。还研究了紫外线和万古霉素对 MRSA 的作用机制，以支持研究结果。采用主成分分析（PCA）和线性判别分析（LDA），揭示了未经处理（对照 I）、未经处理且在环境空气中孵育（对照 II）、用 470nm 蓝光照射、用 253.5nm 紫外线照射和万古霉素处理的 MRSA 五个组的 MRSA 样本聚类。PCA-LDA 分析的载荷图揭示了蛋白质（1683、1656、1596、1542cm）、脂质（1743、1409cm）和光谱中核酸区域（1060、1087cm）的重要功能基团，这些基团负责对蓝光照射光谱和对照光谱进行分类。聚类向量图和得分图显示，紫外线照射光谱与蓝光照射光谱在生化上最为相似；然而，一些波数发生了偏移。在 νPO 带（从 1228 到 1238cm）、DNA 骨架（从 970 到 966cm）和 DNA 碱基对振动（从 1717 到 1712cm）处，蓝光和紫外线照射的负载图之间的偏移表明 DNA 构象在光照下发生了独特的变化。我们的研究结果表明，用 470nm 光照射 MRSA 会诱导 A-DNA 断裂，而 B-DNA 对蓝光的损伤更具抵抗力。蓝光和紫外线处理 MRSA 的作用是互补的，与万古霉素的已知抗菌作用不同。此外，已知紫外线诱导的 DNA 断裂主要针对 B-DNA，这与 FTIR 的发现一致。总的来说，结果表明，光和万古霉素的结合可能是治疗 MRSA 感染的更有效方法。
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