Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
Clin Microbiol Infect. 2018 Jul;24(7):778.e7-778.e14. doi: 10.1016/j.cmi.2017.10.029. Epub 2017 Nov 3.
Antibiotic combinations are often used for carbapenemase-producing Enterobacteriaceae (CPE) but more data are needed on the optimal selection of drugs. This study aimed to evaluate the feasibility of a novel automated method based on time-lapse microscopy (the oCelloScope, Philips BioCell A/S, Allerød, Denmark) to determine in vitro combination effects against CPE and to discuss advantages and limitations of the oCelloScope in relation to standard methods.
Four Klebsiella pneumoniae and two Escherichia coli were exposed to colistin, meropenem, rifampin and tigecycline, alone and in combination. In the oCelloScope experiments, a background corrected absorption (BCA) value of ≤8 at 24 h was used as a primary cut-off indicating inhibition of bacterial growth. A new approach was used to determine synergy, indifference and antagonism based on the number of objects (bacteria) in the images. Static time-kill experiments were performed for comparison.
The time-kill experiments showed synergy with 12 of 36 regimens, most frequently with colistin plus rifampin. BCA values ≤8 consistently correlated with 24-h bacterial concentrations ≤6 log CFU/mL. The classification of combination effects agreed with the time-kill results for 33 of 36 regimens. In three cases, the interactions could not be classified with the microscopy method because of low object counts.
Automated time-lapse microscopy can accurately determine the effects of antibiotic combinations. The novel method is highly efficient compared with time-kill experiments, more informative than checkerboards and can be useful to accelerate the screening for combinations active against multidrug-resistant Gram-negative bacteria.
产碳青霉烯酶肠杆菌科（CPE）常采用抗生素联合治疗，但仍需要更多数据来优化药物选择。本研究旨在评估基于时相差显微镜（oCelloScope，丹麦 Allerød 的 Philips BioCell A/S 公司）的新型自动化方法在体外评估 CPE 联合药敏试验中的可行性，并讨论 oCelloScope 相对于标准方法的优势和局限性。
单独及联合应用黏菌素、美罗培南、利福平及替加环素，对 4 株肺炎克雷伯菌和 2 株大肠埃希菌进行药敏试验。在 oCelloScope 试验中，24 小时时背景校正吸光度（BCA）值≤8 作为细菌生长抑制的主要截断值。采用一种新方法基于图像中的目标（细菌）数量来确定协同、不相关和拮抗作用。进行了静态时间杀伤实验进行比较。
时间杀伤实验显示 36 种方案中有 12 种方案具有协同作用，最常见的是黏菌素联合利福平。BCA 值≤8 与 24 小时细菌浓度≤6 log CFU/ml 始终相关。36 种方案中的 33 种方案的组合效果分类与时间杀伤结果一致。在三种情况下，由于目标数量低，显微镜方法无法对相互作用进行分类。
自动时相差显微镜可以准确地确定抗生素联合用药的效果。与时间杀伤实验相比，新方法效率更高，比棋盘法提供的信息更多，可用于加速筛选对多药耐药革兰氏阴性菌有效的联合用药。
