Yao William, Kuan Edward C, Francis Nathan C, St John Maie A, Grundfest Warren S, Taylor Zachary D
Department of Bioengineering, Henry Samueli School of Engineering and Applied Science, University of California (UCLA), Los Angeles, California.
Department of Head and Neck Surgery, UCLA Medical Center, Los Angeles, California.
Lasers Surg Med. 2017 Jul;49(5):539-547. doi: 10.1002/lsm.22627. Epub 2017 Mar 23.
Bacterial biofilm formation within chronic wound beds, which provides an effective barrier against antibiotics, is a known cause of recalcitrant infections and a significant healthcare burden, often requiring repeated surgical debridements. Laser-generated shockwaves (LGS) is a novel, minimally invasive, and nonthermal modality for biofilm mechanical debridement which utilizes compressive stress waves, generated by photonic absorption in thin titanium films to mechanically disrupt the biofilm. Prior studies have demonstrated LGS monotherapy to be selectively efficacious for biofilm disruption and safe for host tissues. In this study, we sought to determine if LGS can enhance the antimicrobial activity and biofilm disruption capability of topical antibiotic therapy.
STUDY DESIGN/MATERIALS AND METHODS: Staphylococcus epidermidis biofilms grown in vitro on glass were treated with topical gentamicin (31, 62, and 124 μg/ml) with and without LGS (n = 3-11/treatment group). Mechanical shockwaves were generated with a 1,064 nm Nd:YAG laser (laser fluence 110.14 mJ/mm , pulse duration 5 ns, spot size 3 mm). Following a 24-hour incubation period, bacterial viability was assessed by determining the number of colony-forming units (CFU) via the Miles and Misra method. Residual biofilm bioburden was analyzed using the crystal violet biofilm assay.
With gentamicin monotherapy, CFU density (CFU/mm ) at 31, 62, and 124 μg/ml were (282 ± 84) × 10 , (185 ± 34) × 10 , and (113 ± 9) × 10 , respectively. With LGS and gentamicin therapy, CFU density decreased to (170 ± 44) × 10 , (89 ± 24) × 10 , and (43 ± 3) × 10 , respectively (P = 0.1704, 0.0302, and 0.0004 when compared with gentamicin alone). Biofilm burden as measured by the assay in the gentamicin 31, 62, and 124 μg/ml groups was reduced by 80%, 95%, and 98% when LGS was added (P = 0.0102, >0.0001, and 0.0001 for all groups when compared with gentamicin alone). Furthermore, samples treated with LGS saw an increase in susceptibility to gentamicin, in terms of reduced biofilm bioburden and CFU densities.
LGS enhances the efficacy of topical antibiotics in an in vitro model. This has significant implications for clinical applications in the management of chronic soft tissue infections and recalcitrant chronic rhinosinusitis. Lasers Surg. Med. 49:539-547, 2017. © 2017 Wiley Periodicals, Inc.
慢性伤口床内细菌生物膜的形成是顽固性感染的一个已知原因，也是一项重大的医疗负担，通常需要反复进行外科清创，因为它为抗生素提供了有效的屏障。激光产生的冲击波（LGS）是一种用于生物膜机械清创的新型、微创且非热的方式，它利用薄钛膜中的光子吸收产生的压缩应力波来机械性破坏生物膜。先前的研究表明，LGS单一疗法对生物膜破坏具有选择性疗效，且对宿主组织安全。在本研究中，我们试图确定LGS是否能增强局部抗生素治疗的抗菌活性和生物膜破坏能力。
研究设计/材料与方法：在体外玻璃上生长的表皮葡萄球菌生物膜，用局部庆大霉素（31、62和124μg/ml）进行处理，有或没有LGS（每个治疗组n = 3 - 11）。用1064nm的Nd:YAG激光产生机械冲击波（激光能量密度110.14mJ/mm²，脉冲持续时间5ns，光斑尺寸3mm）。经过24小时的孵育期后，通过Miles和Misra方法确定菌落形成单位（CFU）的数量来评估细菌活力。使用结晶紫生物膜测定法分析残留生物膜生物负荷。
单独使用庆大霉素治疗时，31、62和124μg/ml的CFU密度（CFU/mm²）分别为(282 ± 84)×10⁵、(185 ± 34)×10⁵和(113 ± 9)×10⁵。联合LGS和庆大霉素治疗时，CFU密度分别降至(170 ± 44)×10⁵、(89 ± 24)×10⁵和(43 ± 3)×10⁵（与单独使用庆大霉素相比，P分别为0.1704、0.0302和0.0004）。在31、62和124μg/ml庆大霉素组中，添加LGS后，通过该测定法测得的生物膜负荷分别降低了80%、95%和98%（与单独使用庆大霉素相比，所有组P均为0.0102、>0.0001和0.0001）。此外，用LGS处理的样本在生物膜生物负荷和CFU密度降低方面，对庆大霉素的敏感性增加。
在体外模型中，LGS增强了局部抗生素的疗效。这对于慢性软组织感染和顽固性慢性鼻窦炎管理的临床应用具有重要意义。《激光外科与医学》49:539 - 547, 2017。© 2017威利期刊公司
