Li Bing, Qiu Yong, Glidle Andrew, Cooper Jon, Shi HanChang, Yin HuaBing
Environmental Simulation and Pollution Control State-key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084, China.
Analyst. 2014 Jul 7;139(13):3305-13. doi: 10.1039/c4an00170b.
Bacteria persistence is a well-known phenomenon, where a small fraction of cells in an isogenic population are able to survive high doses of antibiotic treatment. Since the persistence is often associated with single cell behaviour, the ability to study the dynamic response of individual cells to antibiotics is critical. In this work, we developed a gradient microfluidic system that enables long-term tracking of single cell morphology under a wide range of inhibitor concentrations. From time-lapse images, we calculated bacterial growth rates based on the variations in cell mass and in cell number. Using E. coli and Comamonas denitrificans to amoxicillin inhibition as model systems, we found the IC50 determined via both methods are in a good agreement. Importantly, the growth rates together with morphological dynamics of individual cells has led to the discovery of a new form of persistence to amoxicillin. Normal cells that are sensitive to amoxicillin gain persistence or recover from the killing process, if they have had an opportunity to utilise the cytoplasm released from lysed cells close-by. We term this acquired persistence in normal growing cells "opportunistic persistence". This finding might shed new insights into biofilm resistance and the effect of antibiotics on environmental microbes.
细菌持久性是一种众所周知的现象，即同基因群体中的一小部分细胞能够在高剂量抗生素治疗下存活。由于持久性通常与单细胞行为相关，因此研究单个细胞对抗生素的动态反应能力至关重要。在这项工作中，我们开发了一种梯度微流控系统，该系统能够在广泛的抑制剂浓度范围内长期跟踪单细胞形态。从延时图像中，我们根据细胞质量和细胞数量的变化计算细菌生长速率。以大肠杆菌和反硝化丛毛单胞菌对阿莫西林抑制作用为模型系统，我们发现通过两种方法测定的IC50吻合良好。重要的是，单个细胞的生长速率以及形态动力学导致发现了一种对阿莫西林的新的持久性形式。对阿莫西林敏感的正常细胞如果有机会利用附近裂解细胞释放的细胞质，就会获得持久性或从杀伤过程中恢复。我们将正常生长细胞中这种获得的持久性称为“机会性持久性”。这一发现可能为生物膜抗性以及抗生素对环境微生物的影响提供新的见解。
