Department of Ophthalmology and Visual Sciences, Escola Paulista de Medicina-Universidade Federal de São Paulo, São Paulo, Brazil.
Institute of Physics of São Carlos, Universidade de São Paulo, São Carlos, Brazil.
Transl Vis Sci Technol. 2023 Sep 1;12(9):9. doi: 10.1167/tvst.12.9.9.
In vitro evaluation of rose bengal (RB) photoactivated by our custom-built green light-emitting diode (LED) source for the growth inhibition of bacterial strains and rapidly growing mycobacterial (RGM) isolates in infectious keratitis.
Six corneal clinical bacteria isolates were included in this study: two Gram-positive bacteria (methicillin-resistant Staphylococcus aureus [MRSA] and Staphylococcus epidermidis), two Gram-negative bacteria (Pseudomonas aeruginosa and Serratia marcescens), and two RGM (Mycobacterium chelonae and Mycobacterium abscessus). Microorganisms were cultured and incubated at specific conditions and prepared in suspensions to adjust their concentration to 104 cells/mL. Different treatments were conducted in triplicates: Group I, no treatment; Group II, treated with 0.1% rose bengal alone (exposed to dark for 30 minutes); Group III, exposed to custom green LED for 30 minutes (12.87 J/cm2); and Group IV, treated with 0.1% rose bengal and exposed to custom green LED for 30 minutes. Agar plates were incubated at specific conditions and photographed after growth for pixel analyses.
Complete growth inhibition of all bacteria and RGM was observed in Group IV. MRSA and S. epidermidis in Group II also showed complete growth inhibition.
The custom-built green LED presented good activity by photoactivating RB and inhibiting micro-organism growth. For the first time, we demonstrated the expressive growth inhibition effect of RB against S. epidermidis, RGM, and S. marcescens. Clinical treatment with RB may offer an alternate adjunct therapy for corneal surface infections.
Validating in vitro the custom-built green LED encourages the clinical application for the treatment of infectious keratitis.
评估我们自制的绿光发光二极管（LED）源对细菌和快速生长分枝杆菌（RGM）分离株在感染性角膜炎中生长抑制的影响。
本研究纳入了 6 种角膜临床细菌分离株：两种革兰氏阳性菌（耐甲氧西林金黄色葡萄球菌[MRSA]和表皮葡萄球菌）、两种革兰氏阴性菌（铜绿假单胞菌和粘质沙雷氏菌）和两种 RGM（脓肿分枝杆菌和龟分枝杆菌）。微生物在特定条件下培养和孵育，并制备成悬浮液，将其浓度调整至 104 个细胞/mL。进行了三种不同的处理：组 I，无处理；组 II，单独用 0.1%玫瑰红苯并卟啉处理（暗处理 30 分钟）；组 III，用定制的绿光 LED 照射 30 分钟（12.87 J/cm2）；组 IV，用 0.1%玫瑰红苯并卟啉处理并暴露于定制的绿光 LED 下 30 分钟。琼脂平板在特定条件下孵育，生长后拍照进行像素分析。
组 IV 中所有细菌和 RGM 的生长完全受到抑制。组 II 中的 MRSA 和表皮葡萄球菌也表现出完全的生长抑制。
定制的绿光 LED 通过光激活 RB 并抑制微生物生长表现出良好的活性。我们首次证明 RB 对表皮葡萄球菌、RGM 和粘质沙雷氏菌具有显著的生长抑制作用。RB 临床治疗可能为角膜表面感染提供一种替代的辅助治疗方法。
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