基于FT-IR研究环丙沙星和白花丹素对金黄色葡萄球菌的抗菌作用

Study of the Antimicrobial Activity of Ciprofloxacin and Plumbagin against Staphylococcus Aureus Based on FT-IR

摘要: 目的：本研究旨在探讨环丙沙星(CIP)与白花丹素(PLU)对不同生长阶段的金黄色葡萄球菌(SA)的动态杀菌过程及其细胞结构改变。方法：利用剂量–反应曲线和时间杀伤曲线评估两种药物在指数期和稳定期的杀菌动力学；采用傅里叶变换红外光谱(FT-IR)监测细菌在药物作用后细菌细胞膜、蛋白质、核酸等结构及胞外多糖(EPS)的变化；利用主成分分析(PCA)和支持向量机(SVM)模型对光谱数据进行特征提取和分类验证；采用透射电子显微镜(TEM)技术观察药物处理前后SA的超微结构变化。结果：CIP对指数期SA杀伤迅速，而PLU在稳定期表现出更强的抑制作用，两药联用在不同生长阶段均表现出相加或协同效应。光谱分析证实，CIP主要破坏细胞膜完整性并在作用后期损伤核酸结构；PLU虽对膜破坏有限，但显著改变蛋白质空间构象，单独或与CIP联合显著减少了EPS分泌。PCA显示各处理组间差异显著，SVM模型分类准确率最高达100%。TEM显示CIP和PLU均破坏了SA的细胞膜。结论：本研究展示了CIP与PLU在金黄色葡萄球菌上的多靶点联合作用(膜、蛋白、核酸及EPS等)，为应对耐药性贡献了潜在策略，为时序性联合用药提供了依据，并展示了FT-IR在监测抗菌动态过程中的潜在应用价值。

Abstract: Objective: This study aims to investigate the dynamic bactericidal process and associated changes in cell structure of Staphylococcus aureus (SA) at different growth stages following treatment with ciprofloxacin (CIP) and plumbagin (PLU). Methods: Dose-response curves and time-kill curves were utilised to evaluate the bactericidal kinetics of the two drugs during the log and stationary phases; Fourier transform infrared spectroscopy (FT-IR) was employed to monitor changes in bacterial cell membranes, proteins, nucleic acids and extracellular polysaccharides (EPS) following drug exposure; principal component analysis (PCA) and support vector machine (SVM) models were used for feature extraction and classification validation of the spectral data; The ultrastructural changes in SA before and after drug treatment were observed using transmission electron microscopy (TEM). Results: CIP rapidly killed SA during the log phase, whilst PLU exhibited stronger inhibitory effects during the stationary phase; the combination of the two drugs demonstrated additive or synergistic effects across different growth stages. Spectral analysis confirmed that CIP primarily disrupted cell membrane integrity and damaged nucleic acid structures in the later stages of action; although PLU caused limited membrane disruption, it significantly altered the spatial conformation of proteins and, either alone or in combination with CIP, significantly reduced EPS secretion. PCA analysis revealed significant differences between treatment groups, with the SVM model achieving a classification accuracy of up to 100%. Conclusion: This study demonstrates the multi-targeted synergistic effects of CIP and PLU against Staphylococcus aureus (acting on membranes, proteins, nucleic acids, and EPS, among others), offering a potential strategy for combating antimicrobial resistance, providing a basis for sequential combination therapy, and highlighting the potential value of FT-IR in monitoring the dynamics of antimicrobial activity.