Department of Microbiology, Hamadan University of Medical Sciences, Hamadan, Iran.
Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
Photodiagnosis Photodyn Ther. 2019 Mar;25:406-413. doi: 10.1016/j.pdpdt.2019.01.028. Epub 2019 Jan 23.
Burn patients are particularly susceptible to microbial infection. Staphylococcus aureus causes burn wound, impetigo and cellulitis. Although sub-lethal antimicrobial photodynamic therapy (aPDT) would not result in microorganism killing, it can considerably influence microbial virulence factor.
Twelve methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) isolated from burns patients. To determine the sub-lethal dose of aPDT, 12 clinical isolates of S. aureus photosensitized with 100 μg ml toluidine blue O (TBO) and irradiated by light emitting diode (LED) with a wavelength of 630 ± 10 nm and energy densities of 52.0, 104.1, and 156.2 J/cm, then bacterial viability was measured. The effects of sub-lethal aPDT on the expression levels of ica ABCD and ica R genes were assessed by quantitative Real-time PCR (qRT-PCR) method.
Fifty and 100 μg ml of TBO significantly reduced the mean cell survival in the MRSA (2.5 - 3 log) and MSSA (2.75-3.1 log) isolates. The average expression levels of icaA, ica B, ica C, and ica D in the MRSA and MSSA isolates were decreased by (12, 14, 11, and 9) and (13, 14.5, 12, and 9.5) fold change, respectively (P < 0.05). However, the expression of ica R gene was decreased by 6 and 8 folds change in MRSA and MSSA, respectively.
The potential of TBO-mediated aPDT could reduce the expression of ica ABCD as important genes involved in biofilm formation and ica R gene as a repressor of the ica operon. Therefore, the use of aPDT agents as a complementary therapy in wound infections of burn patients is recommended.
烧伤患者特别容易受到微生物感染。金黄色葡萄球菌会导致烧伤创面、脓疱病和蜂窝织炎。虽然亚致死剂量的光动力抗菌疗法（aPDT）不会导致微生物死亡，但它可以显著影响微生物毒力因子。
从烧伤患者中分离出 12 株耐甲氧西林金黄色葡萄球菌（MRSA）和甲氧西林敏感金黄色葡萄球菌（MSSA）。为了确定 aPDT 的亚致死剂量，用 100μg/ml 的甲苯胺蓝 O（TBO）对 12 株金黄色葡萄球菌进行敏化，然后用波长为 630±10nm 和能量密度为 52.0、104.1 和 156.2J/cm 的发光二极管（LED）照射，然后测量细菌的存活率。通过实时荧光定量 PCR（qRT-PCR）方法评估亚致死 aPDT 对 icaABCD 和 icaR 基因表达水平的影响。
50μg/ml 和 100μg/ml 的 TBO 显著降低了 MRSA（2.5-3 对数）和 MSSA（2.75-3.1 对数）分离株的平均细胞存活率。MRSA 和 MSSA 分离株中 icaA、icaB、icaC 和 icaD 的平均表达水平分别降低了 12、14、11 和 9 倍和 13、14.5、12 和 9.5 倍（P<0.05）。然而，MRSA 和 MSSA 的 icaR 基因表达水平分别降低了 6 和 8 倍。
TBO 介导的 aPDT 可能降低与生物膜形成有关的重要基因 icaABCD 的表达和 ica 操纵子的抑制剂 icaR 基因的表达。因此，建议将 aPDT 剂作为烧伤患者伤口感染的辅助治疗。
