School of Pharmacy, Queen's University of Belfast, Belfast, United Kingdom.
PLoS One. 2012;7(8):e44289. doi: 10.1371/journal.pone.0044289. Epub 2012 Aug 31.
Bacteria exist, in most environments, as complex, organised communities of sessile cells embedded within a matrix of self-produced, hydrated extracellular polymeric substances known as biofilms. Bacterial biofilms represent a ubiquitous and predominant cause of both chronic infections and infections associated with the use of indwelling medical devices such as catheters and prostheses. Such infections typically exhibit significantly enhanced tolerance to antimicrobial, biocidal and immunological challenge. This renders them difficult, sometimes impossible, to treat using conventional chemotherapeutic agents. Effective alternative approaches for prevention and eradication of biofilm associated chronic and device-associated infections are therefore urgently required. Atmospheric pressure non-thermal plasmas are gaining increasing attention as a potential approach for the eradication and control of bacterial infection and contamination. To date, however, the majority of studies have been conducted with reference to planktonic bacteria and rather less attention has been directed towards bacteria in the biofilm mode of growth. In this study, the activity of a kilohertz-driven atmospheric pressure non-thermal plasma jet, operated in a helium oxygen mixture, against Pseudomonas aeruginosa in vitro biofilms was evaluated. Pseudomonas aeruginosa biofilms exhibit marked susceptibility to exposure of the plasma jet effluent, following even relatively short (≈ 10's s) exposure times. Manipulation of plasma operating conditions, for example, plasma operating frequency, had a significant effect on the bacterial inactivation rate. Survival curves exhibit a rapid decline in the number of surviving cells in the first 60 seconds followed by slower rate of cell number reduction. Excellent anti-biofilm activity of the plasma jet was also demonstrated by both confocal scanning laser microscopy and metabolism of the tetrazolium salt, XTT, a measure of bactericidal activity.
细菌以复杂的、有组织的群体形式存在于大多数环境中，这些群体由嵌入在自我产生的水合细胞外聚合物基质中的静止细胞组成，这些细胞外聚合物基质被称为生物膜。细菌生物膜是慢性感染和与留置医疗设备（如导管和假体）相关感染的普遍且主要原因。这些感染通常表现出对抗菌、杀菌和免疫挑战的显著增强的耐受性。这使得它们难以（有时甚至不可能）使用传统的化疗药物进行治疗。因此，迫切需要有效的替代方法来预防和消除与生物膜相关的慢性和与设备相关的感染。大气压非热等离子体作为一种消除和控制细菌感染和污染的潜在方法，越来越受到关注。然而，迄今为止，大多数研究都参考浮游细菌进行，而对生物膜生长模式下的细菌关注较少。在这项研究中，评估了在氦氧混合物中运行的千赫兹驱动大气压非热等离子体射流对体外铜绿假单胞菌生物膜的活性。铜绿假单胞菌生物膜对等离子体射流流出物的暴露表现出明显的敏感性，即使暴露时间相对较短（约 10's s）也是如此。例如，等离子体工作频率等等离子体工作条件的操纵对细菌失活率有显著影响。生存曲线显示，在最初的 60 秒内，存活细胞数量迅速减少，然后细胞数量减少的速度较慢。通过共聚焦扫描激光显微镜和四唑盐 XTT 的代谢（一种杀菌活性的测量）也证明了等离子体射流的出色抗生物膜活性。
