Hampden-Martin Alistair, Fothergill Jo, El Mohtadi Mohamed, Chambers Lucy, Slate Anthony J, Whitehead Kathryn A, Shokrollahi Kayvan
Faculty of Health and Life Sciences, University of Liverpool, Liverpool, UK.
Institute of Infection and Global Heath, University of Liverpool, Liverpool, UK.
Access Microbiol. 2021 Oct 27;3(10):000273. doi: 10.1099/acmi.0.000273. eCollection 2021.
Photodynamic antimicrobial chemotherapy (PACT) is a novel alternative antimicrobial therapy that elicits a broad mechanism of action and therefore has a low probability of generating resistance. Such properties make PACT ideally suited for utilization in localized applications such as burn wounds. The aim of this study was to determine the antimicrobial activity of MB and temoporfin against both a isolate and a isolate in light (640 nm) and dark conditions at a range of time points (0-20 min). A isolate and a isolate were treated with methylene blue (MB) and temoporfin under different conditions following exposure to light at 640 nm and in no-light (dark) conditions. Bacterial cell viability [colony-forming units (c.f.u.) ml] was then calculated. Against , when MB was used as the photosensitizer, no phototoxic effect was observed in either light or dark conditions. After treatment with temoporfin, a reduction of less than one log (7.00×10 c.f.u. ml) was observed in the light after 20 min of exposure. However, temoporfin completely eradicated in both light and dark conditions after 1 min (where a seven log reduction in c.f.u. ml was observed). Methylene blue resulted in a loss of viability, with a two log reduction in bacterial viability (c.f.u. ml) reported in both light and dark conditions after 20 min exposure time. Temoporfin demonstrated greater antimicrobial efficacy than MB against both the and isolates tested. At 12.5 µM temoporfin resulted in complete eradication of . In light of this study, further research into the validity of PACT, coupled with the photosensitizers (such as temoporfin), should be conducted in order to potentially develop alternative antimicrobial treatment regimes for burn wounds.
光动力抗菌化学疗法（PACT）是一种新型的抗菌替代疗法，其作用机制广泛，因此产生耐药性的可能性较低。这些特性使PACT非常适合用于烧伤创面等局部应用。本研究的目的是确定亚甲蓝（MB）和替莫泊芬在一系列时间点（0 - 20分钟）的光照（640nm）和黑暗条件下对一种分离株和另一种分离株的抗菌活性。在640nm光照和无光（黑暗）条件下，将一种分离株和另一种分离株在不同条件下用亚甲蓝（MB）和替莫泊芬处理。然后计算细菌细胞活力[菌落形成单位（c.f.u.）/毫升]。对于第一种分离株，当使用MB作为光敏剂时，在光照或黑暗条件下均未观察到光毒性作用。用替莫泊芬处理后，光照20分钟后观察到细菌数量减少不到一个对数（7.00×10 c.f.u./毫升）。然而，替莫泊芬在光照和黑暗条件下1分钟后均可完全根除该分离株（此时观察到c.f.u./毫升减少了七个对数）。亚甲蓝导致第二种分离株活力丧失，暴露20分钟后，在光照和黑暗条件下细菌活力（c.f.u./毫升）均报告减少了两个对数。替莫泊芬对所测试的两种分离株均显示出比亚甲蓝更高的抗菌效力。在12.5µM时，替莫泊芬可完全根除第二种分离株。鉴于本研究，应进一步研究PACT与光敏剂（如替莫泊芬）结合的有效性，以便有可能开发出用于烧伤创面的替代抗菌治疗方案。
