Department of Chemical Engineering, Indian Institute of Technology Delhi, Delhi, India.
Molecular Diagnostics and Biomarkers Lab, Gleneagles Global Hospitals, Lakdi ka pul, Hyderabad, India.
J Clin Microbiol. 2018 Aug 27;56(9). doi: 10.1128/JCM.00408-18. Print 2018 Sep.
Bacterial infections affect more than 2 million people annually. Of these, systemic infections caused by bacteria in critically ill patients may lead to life-threatening conditions such as sepsis. We have developed a point-of-care (POC) device called Septiflo that can detect and stratify the Gram status of bloodstream bacterial infections in less than 10 min from a drop of human plasma. It works on the principle of identifying pathogen-associated molecular patterns (PAMPs), such as lipopolysaccharides (LPS) and lipoteichoic acid (LTA) that are released into the bloodstream at the onset of Gram-negative and Gram-positive bacterial infections, respectively. The biomarkers are captured on a membrane without a receptor, and the Gram status specificity is conferred by the ligands attached to gold nanoparticles (AuNPs) used as signal amplification probes. The ultrasensitive colorimetric results are read by eye down to a 100-fg/ml detection limit without an instrument. No cross-interference between the PAMPs is seen during Gram stratification. Septiflo results also display better performance than commercial enzyme-linked immunosorbent assays (ELISAs). Tests performed on 60 clinical samples from patients showed a correlation accuracy of 70% against procalcitonin (PCT), an accepted surrogate biomarker for sepsis. A direct comparison with eubacterial PCR yielded up to 94% accuracy in 31 patients at a chosen cutoff level for LPS and LTA and area under the curve (AUC) values of 0.927 and 0.885, respectively, though blood culture was negative for most samples. The high sensitivity, low cost, and simple bedside utility of the assay may aid in better sepsis management apparently at the presymptomatic stage, lowering empirical therapy, medical costs, antimicrobial resistance, and mortality.
细菌感染每年影响超过 200 万人。其中，重症患者由细菌引起的全身感染可能导致危及生命的情况，如败血症。我们开发了一种即时护理（POC）设备，称为 Septiflo，它可以在不到 10 分钟的时间内从一滴人血浆中检测和分层血流细菌感染的革兰氏状态。它的工作原理是识别病原体相关分子模式（PAMPs），例如脂多糖（LPS）和脂磷壁酸（LTA），它们分别在革兰氏阴性和革兰氏阳性细菌感染开始时释放到血液中。生物标志物被捕获在没有受体的膜上，革兰氏状态特异性由用作信号放大探针的金纳米粒子（AuNPs）上的配体赋予。超灵敏的比色结果可以通过肉眼读取，检测限低至 100fg/ml，无需仪器。在革兰氏分层过程中没有看到 PAMPs 之间的交叉干扰。Septiflo 的结果也显示出比商业酶联免疫吸附测定（ELISA）更好的性能。对来自患者的 60 个临床样本进行的测试显示，与降钙素原（PCT）的相关性准确率为 70%，PCT 是败血症的公认替代生物标志物。与细菌 16S rRNA PCR 的直接比较在选定的 LPS 和 LTA 截止水平下，在 31 名患者中达到了高达 94%的准确率，并且 AUC 值分别为 0.927 和 0.885，尽管大多数样本的血培养均为阴性。该检测方法的高灵敏度、低成本和简单的床边实用性可能有助于在明显的无症状阶段更好地管理败血症，降低经验性治疗、医疗成本、抗生素耐药性和死亡率。
