2012年9月17日 讯 /生物谷BIOON/ --近日，来自美国科学家一项最新的研究成果揭示了一种新型的微流体技术，用于快速进行金黄色葡萄球菌的抗生素敏感性检测。相关研究成果刊登在了国际杂志Lab on a Chip上。
我们都知道，金黄色葡萄球菌（Staphylococcus aureus）是一种耐药性极强的革兰氏阳性球菌，其在自然界随处都可以发现。该菌由于可分泌包括溶血素、外毒素等多种毒素，可引起人类严重的组织感染。近些年来由于抗生素的不合理使用，使得金黄色葡萄球菌的耐药性逐渐上升，因此开发出有效的治疗手段以及快速的抗生素耐药性检测技术对于科学家来说迫在眉睫。
本文研究就揭示了一种新型的金黄色葡萄球菌抗生素敏感性的快速检测方法。随着细菌对抗生素耐药性的不断增加，依赖于观察细菌生长抑制的标准方法对于当前的抗生素并不适用，因此研究者开发出了一种新型的微流体平台来进行细菌对抗生素的敏感性测试，此技术基于细菌在生物合成过程中的压力激活作用，细菌的这些生物合成过程是研究者最初的抗生素靶点。
研究者使用金黄色葡萄球菌（S. aureus）作为模式对象，同时选择细菌细胞壁的合成作为压力和抗生素的作用靶点来进行研究。酶类和物理压力都可以损伤细菌的细胞壁，β-内酰胺类抗生素可以干扰细胞壁的修复过程，最终导致无耐药性的细菌细胞的死亡，细菌细胞的死亡可以使用荧光标记技术来进行追踪观察，死亡比例可以通过在系统中添加或不添加苯唑西林来进行测定。
研究者Alexis F. Sauer-Budge表示，我们开发出了一种新型的基于微流体检测和压力激活的药敏试验的新型技术，在未来临床试验中，这种新型技术可以帮助研究者检测细菌的多种压力效应以及抗生素敏感性，对于临床治疗细菌性感染具有重要的价值。（生物谷Bioon.com）
doi:10.1039/C2LC40531H
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A microfluidic platform for rapid, stress-induced antibiotic susceptibility testing of Staphylococcus aureus
Maxim Kalashnikov , Jean C. Lee , Jennifer Campbell , Andre Sharon and Alexis F. Sauer-Budge
The emergence and spread of bacterial resistance to ever increasing classes of antibiotics intensifies the need for fast phenotype-based clinical tests for determining antibiotic susceptibility. Standard susceptibility testing relies on the passive observation of bacterial growth inhibition in the presence of antibiotics. In this paper, we present a novel microfluidic platform for antibiotic susceptibility testing based on stress-activation of biosynthetic pathways that are the primary targets of antibiotics. We chose Staphylococcus aureus (S. aureus) as a model system due to its clinical importance, and we selected bacterial cell wall biosynthesis as the primary target of both stress and antibiotic. Enzymatic and mechanical stresses were used to damage the bacterial cell wall, and a β-lactam antibiotic interfered with the repair process, resulting in rapid cell death of strains that harbor no resistance mechanism. In contrast, resistant bacteria remained viable under the assay conditions. Bacteria, covalently-bound to the bottom of the microfluidic channel, were subjected to mechanical shear stress created by flowing culture media through the microfluidic channel and to enzymatic stress with sub-inhibitory concentrations of the bactericidal agent lysostaphin. Bacterial cell death was monitored via fluorescence using the Sytox Green dead cell stain, and rates of killing were measured for the bacterial samples in the presence and absence of oxacillin. Using model susceptible (Sanger 476) and resistant (MW2) S. aureus strains, a metric was established to separate susceptible and resistant staphylococci based on normalized fluorescence values after 60 min of exposure to stress and antibiotic. Because this ground-breaking approach is not based on standard methodology, it circumvents the need for minimum inhibitory concentration (MIC) measurements and long wait times. We demonstrate the successful development of a rapid microfluidic-based and stress-activated antibiotic susceptibility test by correctly designating the phenotypes of 16 additional clinically relevant S. aureus strains in a blinded study. In addition to future clinical utility, this method has great potential for studying the effects of various stresses on bacteria and their antibiotic susceptibility.
