Membrane damage as mechanism of photodynamic inactivation using Methylene blue and TMPyP in Escherichia coli and Staphylococcus aureus
Membrane damage as mechanism of photodynamic inactivation using Methylene blue and TMPyP in Escherichia coli and Staphylococcus aureus
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DOI：
10.1007/s43630-021-00158-z
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发表时间：
2022-01-21
影响因子：
3.1
通讯作者：
Maisch, Tim
中科院分区：
文献类型：
--
作者：
Muehler, Denise;Brandl, Elena;Maisch, Tim
抗生素耐药性的全球威胁需要替代策略来对抗细菌感染。一种支持常规抗生素治疗的有前途的方法是抗菌光动力灭活（aPDI）。这项工作的目的是进一步了解抗菌光动力学原理，使用两种不同化学类别的光敏剂（PS），亚甲蓝（MB）和TMPyP，以及作为革兰氏阴性和革兰氏阳性代表的大肠杆菌和金黄色葡萄球菌。两个物种的浮游生物培养物在有氧条件下培养24小时，然后用MB或TMPyP在不同浓度下处理10分钟的孵育期和随后的照射10分钟。通过CFU测定评价复制能力。使用分光光度计测量PS的累积。使用SYBR绿色和碘化丙啶通过流式细胞术研究细胞质膜完整性。在用TMPyP或MB光动力处理后细菌复制能力的实验中，实现了5 log（10）级的细菌杀灭率。通过分光光度测量显示两种PS的浓度依赖性蓄积，其中发现S的TMPyP蓄积较高，MB蓄积较少。aureus与E.杆菌这是第一次，TMPyP和MB在两种细菌菌株中的膜损伤作用可以使用流式细胞术分析显示。此外，我们发现，复制能力的降低发生在比MB时膜损伤所需的浓度更低的浓度下，这表明膜损伤不是使用MB的aPDI的唯一机制。
The worldwide threat of antibiotic resistance requires alternative strategies to fight bacterial infections. A promising approach to support conventional antibiotic therapy is the antimicrobial photodynamic inactivation (aPDI). The aim of this work was to show further insights into the antimicrobial photodynamic principle using two photosensitizers (PS) of different chemical classes, Methylene Blue (MB) and TMPyP, and the organisms Escherichia coli and Staphylococcus aureus as Gram-negative and Gram-positive representatives. Planktonic cultures of both species were cultured under aerobic conditions for 24 h followed by treatment with MB or TMPyP at various concentrations for an incubation period of 10 min and subsequent irradiation for 10 min. Ability to replicate was evaluated by CFU assay. Accumulation of PS was measured using a spectrophotometer. The cytoplasmic membrane integrity was investigated by flow cytometry using SYBR Green and propidium iodide. In experiments on the replication ability of bacteria after photodynamic treatment with TMPyP or MB, a killing rate of 5 log(10) steps of the bacteria was achieved. Concentration-dependent accumulation of both PS was shown by spectrophotometric measurements whereby a higher accumulation of TMPyP and less accumulation of MB was found for S. aureus as compared to E. coli. For the first time, a membrane-damaging effect of TMPyP and MB in both bacterial strains could be shown using flow cytometry analyses. Furthermore, we found that reduction of the replication ability occurs with lower concentrations than needed for membrane damage upon MB suggesting that membrane damage is not the only mechanism of aPDI using MB.