Biofilms are associated with chronic infection and frequently require surgical intervention even after prolonged antibiotic therapy. Bactericidal antibiotics are often ineffective at eradicating genetically susceptible cells within a biofilm because: 1) most conventional antibiotics target ATP-dependent processes and so work poorly on metabolically indolent persister cells within a biofilm; and 2) the biofilm matrix can act as a physical barrier to drug diffusion of certain classes of antibiotics. Antibiotic therapy that fails to completely eradicate the pathogen leads to chronic and relapsing infections, major financial healthcare burdens and significant mortality. Numerous approaches have been taken to improve biofilm killing but these often fail to achieve eradication. We address this problem with a novel two-pronged strategy with the aim of eradicating biofilm infection using 1) antibiotics which target persister cells as well as 2) improving drug penetration using ultrasound-stimulated phase-change contrast agents (US-PCCA). We previously demonstrated that rhamnolipids, biosurfactant molecules produced by Pseudomonas aeruginosa, significantly potentiated aminoglycoside efficacy against S. aureus biofilm. We have also shown that US-PCCA can transiently disrupt biological barriers to therapeutic macromolecules. We hypothesized that combining antibiotics which target persister cells with US-PCCA to improve drug penetration could eradicate methicillin resistant S. aureus (MRSA) biofilms. To investigate this, we treated MRSA biofilms with a range of conventional and anti-persister antibiotics and/or US-PCCA. We found that vancomycin was significantly potentiated by US-PCCA, but a fraction of cells remained viable after the combination treatment. Aminoglycosides alone or in combination with US-PCCA displayed limited efficacy against MRSA biofilms. In contrast, the anti-persister combination of rhamnolipids and aminoglycosides combined with US-PCCA dramatically reduced biofilm viability, frequently culminating in complete eradication of the biofilm. These data demonstrate that biofilm eradication can be achieved using a combined approach improving drug penetration and therapeutics that target persister cells.

中文翻译：

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利用超声刺激的相变造影剂，提高抗甲氧西林金黄色葡萄球菌生物膜的抗菌功效

生物膜与慢性感染有关，即使经过长时间的抗生素治疗，也经常需要手术干预。杀菌抗生素通常无法消除生物膜中的遗传易感细胞，因为：1）大多数常规抗生素靶向于ATP依赖性过程，因此对生物膜中代谢惰性的持久性细胞的作用很差；2）生物膜基质可以作为某些抗生素类药物扩散的物理屏障。不能彻底根除病原体的抗生素治疗会导致慢性和复发性感染，重大的财务医疗负担和大量的死亡率。已经采取了许多方法来改善对生物膜的杀灭，但是这些方法常常无法根除。我们采用一种新颖的两管齐下的策略来解决这个问题，其目的是使用1）靶向持久性细胞的抗生素以及2）使用超声刺激的相变造影剂（US-PCCA）来改善药物渗透，从而消除生物膜感染。我们以前证明鼠李糖脂，由铜绿假单胞菌产生的生物表面活性剂分子，可显着增强针对金黄色葡萄球菌生物膜的氨基糖苷功效。我们还表明，US-PCCA可以暂时破坏治疗性大分子的生物屏障。我们假设将靶向持久性细胞的抗生素与US-PCCA结合以提高药物渗透性可以根除耐甲氧西林的金黄色葡萄球菌（MRSA）生物膜。为了对此进行调查，我们用一系列常规和抗持久性抗生素和/或US-PCCA处理了MRSA生物膜。我们发现，万古霉素可被US-PCCA显着增强，但在联合治疗后仍有一部分细胞保持活力。单独或与US-PCCA组合使用的氨基糖苷类药物对MRSA生物膜的功效有限。相比之下，鼠李糖脂和氨基糖苷类抗鼠尾草结合US-PCCA则大大降低了生物膜的生存能力，最终导致生物膜的彻底根除。这些数据表明，使用结合的方法提高药物渗透性和靶向持久性细胞的疗法，可以消除生物膜。鼠李糖脂和氨基糖苷类的抗组合杀虫剂与US-PCCA的结合大大降低了生物膜的生存能力，并最终导致生物膜的彻底根除。这些数据表明，使用结合的方法提高药物渗透性和靶向持久性细胞的疗法，可以消除生物膜。鼠李糖脂和氨基糖苷类的抗组合杀虫剂与US-PCCA的结合大大降低了生物膜的生存能力，并最终导致生物膜的彻底根除。这些数据表明，使用结合的方法提高药物渗透性和靶向持久性细胞的疗法，可以消除生物膜。