高射线剂量能提高 PACK 交联的抗菌功效。

High Fluence Increases the Antibacterial Efficacy of PACK Cross-Linking.

机构信息

University of Zurich, CABMM, Laboratory for Ocular Cell Biology Group, Zurich, Switzerland.

Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.

出版信息

Cornea. 2020 Aug;39(8):1020-1026. doi: 10.1097/ICO.0000000000002335.

DOI:10.1097/ICO.0000000000002335

PMID:32304431

Abstract

PURPOSE

Photoactivated chromophore for keratitis cross-linking (PACK-CXL) is used as an adjunct therapy to antibiotic medication in infectious keratitis. This experimental study aimed at quantifying the PACK-CXL efficacy as a function of UV fluence using several bacterial strains and irradiated volumes.

METHODS

Six distinct bacterial strains, including standardized strains and clinically isolated strains from patients with keratitis, were analyzed. Bacterial concentrations between 10 and 10 cells/mL were used (simulating small corneal ulcers). Volumes of either 11 μL (≈285 μm stromal thickness) or 40 μL (≈1000 μm stromal thickness) were irradiated within a microtiter plate at different fluences (5.4-27 J/cm) and irradiances (3, 9 and 18 mW/cm). The ratio of bacterial killing (B†) was determined to evaluate the antimicrobial efficacy of PACK-CXL.

RESULTS

B† was similar (51 ± 11%) in bacterial concentrations between 10 and 10 per ml. In 11 μL volume, Staphylococcus aureus (SA) 8325-4 ATCC 29213, Bacillus subtilis (BS) 212901, and Pseudomonas aeruginosa (PA) 2016-866624 were most sensitive to PACK-CXL at 5.4 J/cm (on average B† = 49 ± 8%), whereas Klebsiella oxytoca (KO) 2016-86624 (B† = 25%) was least sensitive. When irradiating a larger volume, B† was on average lower in 40 μL (19 ± 18%), compared with 11 μL (45 ± 17%, P < 0.001). By contrast, applying a higher UV fluence increased B† of SA ATCC 29213, from 50% at 5.4 J/cm to 92% at 10.8 J/cm, to 100% at 16.2 J/cm and above.

CONCLUSIONS

Applying higher UV fluences substantially increases the bacterial killing rates. Safety limits for clinical application require further investigation.

摘要

目的

光激活角膜交联用发色团（PACK-CXL）被用作感染性角膜炎抗生素药物的辅助治疗。本实验研究旨在定量评估不同细菌菌株和照射体积下，PACK-CXL 作为紫外线辐照剂量函数的疗效。

方法

分析了六种不同的细菌菌株，包括标准菌株和来自角膜炎患者的临床分离株。使用浓度为 10 到 10 细胞/ml 的细菌（模拟小的角膜溃疡）。在微孔板中以不同的辐照剂量（5.4-27 J/cm）和辐照度（3、9 和 18 mW/cm）照射体积为 11 μL（≈285 μm 基质厚度）或 40 μL（≈1000 μm 基质厚度）。为评估 PACK-CXL 的抗菌效果，测定了细菌杀灭率（B†）。

结果

在浓度为 10 到 10 细胞/ml 之间，B†相似（51 ± 11%）。在 11 μL 体积下，金黄色葡萄球菌（SA）8325-4 ATCC 29213、枯草芽孢杆菌（BS）212901 和铜绿假单胞菌（PA）2016-866624 对 PACK-CXL 最敏感，在 5.4 J/cm 时平均 B†为 49 ± 8%，而产酸克雷伯氏菌（KO）2016-86624 （B†=25%）最不敏感。当照射更大的体积时，在 40 μL 时的 B†平均为 19 ± 18%，而在 11 μL 时为 45 ± 17%（P < 0.001）。相比之下，增加紫外线辐照剂量会显著提高 SA ATCC 29213 的 B†，从 5.4 J/cm 时的 50%增加到 10.8 J/cm 时的 92%，再增加到 16.2 J/cm 及以上时达到 100%。