Post Graduation Program Biomedical Engineering and Bioengineering, Universidade Brasil, Sao Paulo, Brazil.
Instituto de Estudos Avançados, Sao Jose dos Campos, Brazil.
Photochem Photobiol. 2020 May;96(3):618-624. doi: 10.1111/php.13239. Epub 2020 Apr 20.
Ventilator-associated pneumonia (VAP) is an infection that arises after endotracheal intubation affecting patients under intensive care. The presence of the endotracheal tube (ETT) is a risk factor since it is colonized by multispecies biofilm. Antimicrobial photodynamic therapy (aPDT) could be a strategy to decontaminate ETTs. We verify if methylene blue (MB) associated with external illumination of the ETT could be an alternative to destroy biofilm. We performed an in vitro and ex vivo study. In vitro study was performed with P. aeruginosa biofilm grew over ETT for 7 days. After treatment, the surviving cells were cultured for 3 days and the biofilm was analyzed by crystal violet absorbance. Ex vivo study employed ETT obtained from extubated patients. aPDT was performed with MB (100 µm) and red LED (λ = 640±20 nm). We quantified the biofilm thickness and used scanning electron microscopy and fluorescence technique to verify morphological and functional changes after aPDT. Our results showed that bacteria remain susceptible to aPDT after sequential treatments. We also attested that aPDT can reduce biofilm thickness, disrupt biofilm attachment from ETT surface and kill microbial cells. These data suggest that aPDT should be investigated to decrease VAP incidence via ETT decontamination.
呼吸机相关性肺炎（VAP）是一种在重症监护下经气管插管后发生的感染。气管内导管（ETT）的存在是一个危险因素，因为它被多物种生物膜定植。光动力抗菌疗法（aPDT）可能是一种清除 ETT 污染的策略。我们验证了亚甲蓝（MB）联合 ETT 外部光照是否可以破坏生物膜。我们进行了一项体外和离体研究。体外研究是在 P. aeruginosa 生物膜在 ETT 上生长 7 天后进行的。治疗后，将存活细胞培养 3 天，并通过结晶紫吸光度分析生物膜。离体研究使用从拔管患者获得的 ETT。用 MB（100µm）和红色 LED（λ=640±20nm）进行 aPDT。我们量化了生物膜的厚度，并使用扫描电子显微镜和荧光技术来验证 aPDT 后形态和功能的变化。我们的结果表明，在连续治疗后，细菌仍然对 aPDT 敏感。我们还证明，aPDT 可以减少生物膜厚度，破坏生物膜从 ETT 表面的附着，并杀死微生物细胞。这些数据表明，应该通过清除 ETT 来研究 aPDT 以降低 VAP 的发生率。
