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Abstract：
OBJECTIVE: Bacterial biofilms on the surface of prostheses are becoming a rising concern in managing prosthetic joint infections. The inherent resistant features of biofilms render traditional antimicrobial therapy unproductive and revision surgery outcomes uncertain. This situation has prompted the exploration of novel antimicrobial strategies. The synergy of ultrasound microbubbles and vancomycin has been proposed as an efficient alternative for biofilm eradication. The purpose of this study was to evaluate the anti-biofilm effect of stimulated phase-shift acoustic nanodroplets (NDs) combined with vancomycin.
METHODS: We fabricated lipid phase-shift NDs with a core of liquid perfluoropentane. A new phase change mode for NDs incorporating an initial unfocused low-intensity pulsed ultrasound for 5 minutes and a subsequent incubation at 37°C into a 24-hour duration was developed. Methicillin-resistant Staphylococcus aureus (MRSA) biofilms were incubated with vancomycin and NDs under the hybrid stimulation. Biofilm morphology following treatment was determined using confocal laser scanning microscopy and scanning electron microscopy. Resazurin assay was used to quantify bactericidal efficacy against MRSA biofilm bacteria.
RESULTS: NDs treated sequentially with ultrasound and heating at 37°C achieved gradual and substantial ND vaporization and cavitation in a successive process. NDs after stimulation were capable of generating stronger destruction on biofilm structure which was best characterized by residual circular arc margins and more dead bacteria. Furthermore, NDs combined with vancomycin contributed to significantly decreasing the metabolic activity of bacteria in MRSA biofilms (P<0.05).
CONCLUSIONS: Phase-shift acoustic NDs could exert a significant bactericidal effect against MRSA biofilms through a new stimulation mode. Acoustic NDs present advantages over microbubbles for biofilm damage. This anti-biofilm strategy could be used either alone or as an enhancer of traditional antibiotics in the control of prosthetic joint infections.
METHODS: We fabricated lipid phase-shift NDs with a core of liquid perfluoropentane. A new phase change mode for NDs incorporating an initial unfocused low-intensity pulsed ultrasound for 5 minutes and a subsequent incubation at 37°C into a 24-hour duration was developed. Methicillin-resistant Staphylococcus aureus (MRSA) biofilms were incubated with vancomycin and NDs under the hybrid stimulation. Biofilm morphology following treatment was determined using confocal laser scanning microscopy and scanning electron microscopy. Resazurin assay was used to quantify bactericidal efficacy against MRSA biofilm bacteria.
RESULTS: NDs treated sequentially with ultrasound and heating at 37°C achieved gradual and substantial ND vaporization and cavitation in a successive process. NDs after stimulation were capable of generating stronger destruction on biofilm structure which was best characterized by residual circular arc margins and more dead bacteria. Furthermore, NDs combined with vancomycin contributed to significantly decreasing the metabolic activity of bacteria in MRSA biofilms (P<0.05).
CONCLUSIONS: Phase-shift acoustic NDs could exert a significant bactericidal effect against MRSA biofilms through a new stimulation mode. Acoustic NDs present advantages over microbubbles for biofilm damage. This anti-biofilm strategy could be used either alone or as an enhancer of traditional antibiotics in the control of prosthetic joint infections.
摘要：
目的：假体表面的细菌生物膜在治疗假体关节感染中日益受到关注。生物膜的固有抗性特征使得传统的抗微生物疗法无效,并且修正手术结果不确定。这种情况促使人们探索新的抗菌策略。超声微泡和万古霉素的协同作用已被提出作为生物膜根除的有效替代方案。这项研究的目的是评估受激相移声纳米液滴（ND）与万古霉素联合的抗生物膜作用。
方法：我们制造了以液体全氟戊烷为核心的脂质相移ND。开发了一种新的相变模式，用于将初始未聚焦的低强度脉冲超声合并5分钟，然后在37°C下孵育24小时。耐甲氧西林金黄色葡萄球菌（MRSA）生物膜与万古霉素和ND在杂交刺激下孵育。使用共聚焦激光扫描显微镜和扫描电子显微镜测定处理后的生物膜形态。瑞舒林测定用于定量对MRSA生物膜细菌的杀菌效力。
结果：用超声和37°C加热顺序处理的ND在连续过程中实现了逐渐和大量的ND蒸发和空化。刺激后的ND能够对生物膜结构产生更强的破坏，其最佳特征是残留的圆弧边缘和更多的死亡细菌。此外，NDs联合万古霉素可显著降低MRSA生物膜中细菌的代谢活性(P<0.05)。
结论：相移声学ND可以通过一种新的刺激模式对MRSA生物膜产生显著的杀菌作用。声学ND在生物膜损伤方面优于微泡。这种抗生物膜策略可以单独使用或作为传统抗生素的增强剂用于控制假体关节感染。
方法：我们制造了以液体全氟戊烷为核心的脂质相移ND。开发了一种新的相变模式，用于将初始未聚焦的低强度脉冲超声合并5分钟，然后在37°C下孵育24小时。耐甲氧西林金黄色葡萄球菌（MRSA）生物膜与万古霉素和ND在杂交刺激下孵育。使用共聚焦激光扫描显微镜和扫描电子显微镜测定处理后的生物膜形态。瑞舒林测定用于定量对MRSA生物膜细菌的杀菌效力。
结果：用超声和37°C加热顺序处理的ND在连续过程中实现了逐渐和大量的ND蒸发和空化。刺激后的ND能够对生物膜结构产生更强的破坏，其最佳特征是残留的圆弧边缘和更多的死亡细菌。此外，NDs联合万古霉素可显著降低MRSA生物膜中细菌的代谢活性(P<0.05)。
结论：相移声学ND可以通过一种新的刺激模式对MRSA生物膜产生显著的杀菌作用。声学ND在生物膜损伤方面优于微泡。这种抗生物膜策略可以单独使用或作为传统抗生素的增强剂用于控制假体关节感染。
