Laboratory Sciences Research Center, Golestan University of Medical Sciences, Gorgan, Iran; Department of Microbiology, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran.
Medical Cellular and Molecular Research Center, Golestan University of Medical Sciences, Gorgan, Iran.
J Infect Chemother. 2024 Sep;30(9):892-898. doi: 10.1016/j.jiac.2024.03.001. Epub 2024 Mar 2.
Development of multi-, extensively-, and pandrug-resistant (MDR, XDR, and PDR) strains of Pseudomonas aeruginosa remains a major problem in medical care. The present study evaluated the effect of antimicrobial photodynamic therapy (aPDT) as a monotherapy and in combination with colistin against P. aeruginosa isolates.
Two P. aeruginosa isolates recovered from patients with respiratory tract infections were examined in this study. Minimum inhibitory concentration (MIC) of colistin was determined by the colistin broth disk elution (CBDE) and the reference broth microdilution (rBMD) methods. aPDT was performed using the photosensitizer (Ps) riboflavin at several concentrations and a light-emitting diode (LED) emitting blue light for different irradiation times with or without colistin at 1/2 × MIC concentration.
Both PA1 and PA2 isolates were identified as colistin-resistant P. aeruginosa with a MIC ≥4 μg/mL by the CBDE and MICs of 512 μg/mL and 256 μg/mL, respectively, by the rBMD. In aPDT, neither riboflavin nor LED light alone had antibacterial effects. The values of colony forming units per milliliter (CFU/mL) in both isolates were significantly reduced by LED + Ps treatments in a time-dependent manner (LED irradiation time) and dose-dependent manner (Ps concentration). In comparison with control, treatment with Ps (50 μM) + LED (120 s) and Ps (100 μM) + LED (120 s) resulted in 0.27 log CFU/mL and 0.43 log CFU/mL reductions in PA1, and 0.28 log CFU/mL and 0.34 log CFU/mL reductions in PA2, respectively, (P < 0.01). The best results were obtained after the combination of aPDT followed by colistin, which increased bacterial reduction, resulting in a 0.41-0.7 log CFU/mL reduction for PA1 and 0.35-0.83 log CFU/mL reduction for PA2 (P = 0.001).
This study suggests the potential implications of aPDT in combination with antibiotics, such as colistin for treatment of difficult-to-treat P. aeruginosa infections.
铜绿假单胞菌（Pseudomonas aeruginosa）多药耐药（MDR）、广泛耐药（XDR）和泛耐药（PDR）菌株的发展仍然是医疗保健中的一个主要问题。本研究评估了抗菌光动力疗法（aPDT）作为单一疗法以及与多粘菌素联合治疗铜绿假单胞菌分离株的效果。
本研究检测了从呼吸道感染患者中分离出的 2 株铜绿假单胞菌分离株。通过多粘菌素肉汤盘洗脱（CBDE）和参考肉汤微量稀释（rBMD）方法测定多粘菌素的最小抑菌浓度（MIC）。使用不同浓度的光敏剂（PS）核黄素和发出蓝光的发光二极管（LED）进行 aPDT，并在 1/2×MIC 浓度下照射或不照射多粘菌素，进行不同时间的光照。
PA1 和 PA2 分离株均被鉴定为多粘菌素耐药铜绿假单胞菌，CBDE 的 MIC 值≥4μg/ml，rBMD 的 MIC 值分别为 512μg/ml 和 256μg/ml。在 aPDT 中，核黄素和 LED 光单独均无抗菌作用。两种分离株的菌落形成单位数（CFU/ml）均随 LED+Ps 处理时间（LED 照射时间）和剂量（PS 浓度）呈时间依赖性和剂量依赖性显著降低。与对照组相比，PS（50μM）+LED（120s）和 PS（100μM）+LED（120s）处理后，PA1 的 CFU/ml 减少 0.27 log，PA2 的 CFU/ml 减少 0.43 log（P<0.01）。aPDT 联合多粘菌素后效果最佳，细菌减少量增加，PA1 的 CFU/ml 减少 0.41-0.7 log，PA2 的 CFU/ml 减少 0.35-0.83 log（P=0.001）。
本研究表明，光动力疗法联合抗生素（如多粘菌素）治疗治疗困难的铜绿假单胞菌感染具有潜在意义。
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