Laser NIR Irradiation Enhances Antimicrobial Photodynamic Inactivation of Biofilms of Staphylococcus aureus

IF 2.2 3区医学 Q2 DERMATOLOGY

Lasers in Surgery and Medicine Pub Date : 2024-10-03 DOI:10.1002/lsm.23847

Leandro Mamone, Roberto Tomás, Gabriela Di Venosa, Lautaro Gándara, Edgardo Durantini, Fernanda Buzzola, Adriana Casas

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引用次数: 0

Abstract

Objectives

Photodynamic inactivation (PDI) is a powerful technique for eradicating microorganisms, and our group previously demonstrated its effectiveness against planktonic cultures of Staphylococcus aureus bacteria using 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl]porphyrin (TAPP) and visible light irradiation. However, biofilms exhibit a lower sensitivity to PDI, mainly due to limited penetration of the photosensitizer (PS). In the context of emerging antibacterial strategies, near-infrared treatments (NIRTs) have shown promise, especially for combating resistant strains. NIRT can act either through photon absorption by water, causing a thermal effect on bacteria, or by specific chromophores without a significant temperature increase. Our objective was to enhance biofilm sensitivity to TAPP-PDI by pretreatment with NIRT. This combined approach aims to disrupt biofilms and increase the efficacy of TAPP-PDI against bacterial biofilms.

Materials and Methods

In vitro biofilm models of S. aureus RN6390 were utilized. NIRTs involved a 980 nm laser (continuous mode, 7.5 W/cm², 30 s, totaling 225 J/cm²) post-TAPP exposure to enhance photosensitizer accumulation. Subsequent visible light irradiation at 180 J/cm² was employed to perform PDI. Colony-forming unit counts evaluated the synergistic effect on bacterial viability. Scanning electron microscopy visualized the architectural changes in the biofilm structure. TAPP was extracted from bacteria to estimate the impact of NIRT on biofilm penetration.

Results

Using in vitro biofilm models, NIRT application following biofilm exposure to TAPP increased PS accumulation per bacteria. Under these conditions, NIRT induced a transient increase in the temperature of PBS to 46.0 ± 2.6°C (ΔT = 21.5°C). Following exposure to visible light, a synergistic effect emerged, yielding a substantial 4.4 ± 0.1-log CFU reduction. In contrast, the PDI and NIRT treatments individually caused a decrease in viability of 0.9 ± 0.1 and 0.8 ± 0.2-log respectively. Interestingly, preheating TAPP-PBS to 46°C had no significant impact on TAPP-PDI efficacy, suggesting the involvement of thermal and nonthermal effects of NIR action. In addition to the enhanced TAPP penetration, NIRT dispersed the biofilms and induced clefts in the biofilm matrix.

Conclusion

Our findings suggest that NIR irradiation serves as a complementary treatment to PDI. This combined strategy reduces bacterial numbers at lower PS concentrations than standalone PDI treatment, highlighting its potential as an effective and resource-efficient antibacterial approach.

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近红外激光辐照可增强金黄色葡萄球菌生物膜的光动力抗菌灭活作用。

目的：光动力灭活（PDI）是一种根除微生物的强大技术，我们的研究小组曾利用 5,10,15,20-四[4-(3-N,N-二甲基氨基丙氧基)苯基]卟啉（TAPP）和可见光照射证明了它对金黄色葡萄球菌浮游培养物的有效性。然而，生物膜对 PDI 的敏感性较低，这主要是由于光敏剂（PS）的穿透力有限。在新兴的抗菌策略中，近红外疗法（NIRT）已显示出其前景，尤其是在抗耐药菌株方面。近红外疗法可以通过水对光子的吸收对细菌产生热效应，也可以通过特定的发色团对细菌产生热效应，但不会显著升温。我们的目标是通过 NIRT 预处理来提高生物膜对 TAPP-PDI 的敏感性。这种综合方法旨在破坏生物膜，提高 TAPP-PDI 对细菌生物膜的功效：利用金黄色葡萄球菌 RN6390 的体外生物膜模型。在 TAPP 暴露后，使用 980 nm 激光（连续模式，7.5 W/cm2，30 s，总计 225 J/cm2）进行近红外辐射，以增强光敏剂的积累。随后使用 180 J/cm2 的可见光照射进行 PDI。菌落形成单位计数评估了对细菌活力的协同效应。扫描电子显微镜可观察到生物膜结构的变化。从细菌中提取 TAPP，以评估 NIRT 对生物膜渗透的影响：结果：利用体外生物膜模型，在生物膜暴露于 TAPP 后应用 NIRT 增加了细菌的 PS 积累。在这些条件下，近红外辐射诱导 PBS 温度瞬时升高至 46.0 ± 2.6°C (ΔT = 21.5°C)。暴露于可见光后，出现了协同效应，使 CFU 大幅减少 4.4 ± 0.1-log。相比之下，PDI 和 NIRT 处理分别导致存活率下降 0.9 ± 0.1 和 0.8 ± 0.2-log。有趣的是，将 TAPP-PBS 预热至 46°C 对 TAPP-PDI 的功效没有显著影响，这表明近红外作用涉及热效应和非热效应。除了增强 TAPP 穿透力外，近红外辐射还能分散生物膜并诱导生物膜基质裂开：我们的研究结果表明，近红外照射可作为 PDI 的辅助治疗手段。结论：我们的研究结果表明，近红外照射可作为 PDI 的补充治疗方法，与单独的 PDI 治疗相比，这种组合策略可在较低的 PS 浓度下减少细菌数量，从而凸显了其作为一种有效且节约资源的抗菌方法的潜力。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Lasers in Surgery and Medicine 医学-外科

CiteScore

5.40

自引率

12.50%

发文量

119

审稿时长

1 months

期刊介绍： Lasers in Surgery and Medicine publishes the highest quality research and clinical manuscripts in areas relating to the use of lasers in medicine and biology. The journal publishes basic and clinical studies on the therapeutic and diagnostic use of lasers in all the surgical and medical specialties. Contributions regarding clinical trials, new therapeutic techniques or instrumentation, laser biophysics and bioengineering, photobiology and photochemistry, outcomes research, cost-effectiveness, and other aspects of biomedicine are welcome. Using a process of rigorous yet rapid review of submitted manuscripts, findings of high scientific and medical interest are published with a minimum delay.