Department of Chemical Engineering, Loughborough University, Leicestershire, LE11 3TU, UK.
Centre for Biosensors, Bioelectronics and Biodevices (C3Bio), Department of Chemical Engineering, University of Bath, Bath, BA2 7AY, UK.
Biosens Bioelectron. 2019 Dec 1;145:111624. doi: 10.1016/j.bios.2019.111624. Epub 2019 Sep 6.
In spite of the clinical need, there is a major gap in rapid diagnostics for identification and quantitation of E. coli and other pathogens, also regarded as the biggest bottleneck in the fight against the spread of antimicrobial resistant bacterial strains. This study reports for the first time an optical, smartphone-based microfluidic fluorescence sandwich immunoassay capable of quantifying E. coli in buffer and synthetic urine in less than 25 min without sample preparation nor concentration. A limit of detection (LoD) up to 240 CFU/mL, comensurate with cut-off for UTIs (10-10 CFUs/mL) was achieved. Replicas of full response curves performed with 10-10 CFUs/mL of E. coli K12 in synthetic urine yielded recovery values in the range 80-120%, assay reproducibility below 30% and precision below 20%, therefore similar to high-performance automated immunoassays. The unrivalled LoD was mainly linked to the 'open fluidics' nature of the 10-bore microfluidic strips used that enabled passing a large volume of sample through the microcapillaries coated with capture antibody. The new smartphone based test has the potential of being as a rapid, point-of-care test for rule-in of E. coli infections that are responsible for around 80% of UTIs, helping to stop the over-prescription of antibiotics and the monitoring of patients with other symptomatic communicable diseases caused by E. coli at global scale.
尽管存在临床需求，但在鉴定和定量检测大肠杆菌和其他病原体的快速诊断方面仍存在重大差距，这也被认为是对抗抗药性细菌菌株传播的最大瓶颈。本研究首次报道了一种光学的、基于智能手机的微流控荧光三明治免疫分析方法，能够在不到 25 分钟的时间内，无需样品制备和浓缩，即可在缓冲液和合成尿液中定量检测大肠杆菌。检测限（LoD）可达 240 CFU/mL，与尿路感染的截止值（10-10 CFUs/mL）相当。在合成尿液中用 10-10 CFU/mL 的大肠杆菌 K12 进行全响应曲线的复制品，其回收率值在 80-120%范围内，测定重现性低于 30%，精密度低于 20%，因此与高性能自动化免疫分析相当。无与伦比的 LoD 主要与用于的 10 孔微流控条的“开放式流体”性质有关，这使得能够使大量样品通过涂有捕获抗体的微毛细管。这种新的基于智能手机的测试有可能成为一种快速的即时护理检测方法，用于确定约 80%的尿路感染是由大肠杆菌引起的，有助于停止对抗生素的过度处方，并在全球范围内监测由大肠杆菌引起的其他有症状的传染病患者。
