GE Global Research, Niskayuna, New York, USA.
Antimicrob Agents Chemother. 2012 Apr;56(4):2028-36. doi: 10.1128/AAC.05642-11. Epub 2012 Jan 9.
Plasma, a unique state of matter with properties similar to those of ionized gas, is an effective biological disinfectant. However, the mechanism through which nonthermal or "cold" plasma inactivates microbes on surfaces is poorly understood, due in part to challenges associated with processing and analyzing live cells on surfaces rather than in aqueous solution. Here, we employ membrane adsorption techniques to visualize the cellular effects of plasma on representative clinical isolates of drug-resistant microbes. Through direct fluorescent imaging, we demonstrate that plasma rapidly inactivates planktonic cultures, with >5 log(10) kill in 30 s by damaging the cell surface in a time-dependent manner, resulting in a loss of membrane integrity, leakage of intracellular components (nucleic acid, protein, ATP), and ultimately focal dissolution of the cell surface with longer exposure time. This occurred with similar kinetic rates among methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Candida albicans. We observed no correlative evidence that plasma induced widespread genomic damage or oxidative protein modification prior to the onset of membrane damage. Consistent with the notion that plasma is superficial, plasma-mediated sterilization was dramatically reduced when microbial cells were enveloped in aqueous buffer prior to treatment. These results support the use of nonthermal plasmas for disinfecting multidrug-resistant microbes in environmental settings and substantiate ongoing clinical applications for plasma devices.
等离子体是一种具有类似于电离气体性质的独特物质状态，是一种有效的生物消毒剂。然而，由于与在表面上处理和分析活细胞相关的挑战，非热或“冷”等离子体在表面上使微生物失活的机制仍未被充分理解，而非在水溶液中。在这里，我们采用膜吸附技术来可视化等离子体对代表性临床耐药微生物分离株的细胞效应。通过直接荧光成像，我们证明等离子体可迅速使浮游培养物失活，在 30 秒内通过以时间依赖性方式破坏细胞膜而使 >5log(10)的杀灭，导致膜完整性丧失，细胞内成分（核酸、蛋白质、ATP）泄漏，并且随着暴露时间的延长，最终导致细胞表面的局灶性溶解。耐甲氧西林金黄色葡萄球菌（MRSA）、铜绿假单胞菌和白色念珠菌之间存在类似的动力学速率。我们没有观察到相关证据表明，在膜损伤发生之前，等离子体诱导了广泛的基因组损伤或氧化蛋白质修饰。与等离子体是表面性的观点一致，当微生物细胞在治疗前被包裹在水性缓冲液中时，等离子体介导的杀菌作用显著降低。这些结果支持在环境中使用非热等离子体来消毒多药耐药微生物，并证实了等离子体设备的持续临床应用。
