The pipeline of antibiotics has been for decades on an alarmingly low level. Considering the steadily emerging antibiotic resistance, novel tools are needed for early and easy identification of effective anti-infective compounds. In Gram-negative bacteria, the uptake of anti-infectives is especially limited. We here present a surprisingly simple in vitro model of the Gram-negative bacterial envelope, based on 20% (w/v) potato starch gel, printed on polycarbonate 96-well filter membranes. Rapid permeability measurements across this polysaccharide hydrogel allowed to correctly predict either high or low accumulation for all 16 tested anti-infectives in living E. coli. Freeze-fracture TEM supports that the macromolecular network structure of the starch hydrogel may represent a useful surrogate of the Gram-negative bacterial envelope. Machine learning by random forest analysis of in vitro data revealed minimum projection area, molecular mass, and rigidity as the most critical physicochemical parameters for hydrogel permeability, in agreement with reported structural features needed for uptake into Gram-negative bacteria. Correlating our data set of 27 antibiotics from different structural classes to reported MIC values of seven clinically relevant pathogens allowed to distinguish active from non-active compounds based on their low in vitro permeability and in particular to identify poorly permeable antimicrobial candidates before testing them on living bacteria.


中文翻译：

---

基于水凝胶的体外测定可快速预测革兰氏阴性细菌中抗生素的积累。

数十年来，抗生素的销售量一直处于令人震惊的低水平。考虑到稳定出现的抗生素抗性，需要新颖的工具来早期和容易地鉴定有效的抗感染化合物。在革兰氏阴性细菌中，抗感染剂的摄取受到特别限制。我们在此展示了一个出乎意料的简单革兰氏阴性细菌包膜的体外模型，该模型基于印刷在聚碳酸酯96孔滤膜上的20％（w / v）马铃薯淀粉凝胶。跨此多糖水凝胶的快速渗透性测量可正确预测活大肠杆菌中所有16种经过测试的抗感染药的高或低蓄积。冷冻断裂TEM支持淀粉水凝胶的大分子网络结构可以代表革兰氏阴性细菌包膜的有用替代物。通过对体外数据进行随机森林分析的机器学习揭示了最小投影面积，分子质量和刚度是水凝胶渗透性的最关键物理化学参数，这与摄取革兰氏阴性细菌所需的报道结构特征一致。将我们来自不同结构类别的27种抗生素的数据集与报告的7种临床相关病原体的MIC值进行关联，可以根据其体外渗透率低将活性化合物与非活性化合物区分开，特别是在进行活体测试之前鉴定渗透性较差的抗微生物剂菌。与据报道摄取革兰氏阴性细菌所需的结构特征一致。将我们来自不同结构类别的27种抗生素的数据集与报告的7种临床相关病原体的MIC值进行关联，可以根据其体外渗透率低将活性化合物与非活性化合物区分开，特别是在进行活体测试之前鉴定渗透性较差的抗微生物剂菌。与据报道摄取革兰氏阴性细菌所需的结构特征一致。将我们来自不同结构类别的27种抗生素的数据集与报告的7种临床相关病原体的MIC值进行关联，可以根据其体外渗透率低将活性化合物与非活性化合物区分开，特别是在进行活体测试之前鉴定渗透性较差的抗微生物剂菌。