RAPID ELECTROCHEMICAL BIOSENSOR FOR POINT-OF-CARE DIAGNOSIS OF JOINT INFECTION

假体周围关节感染(PJI)是全关节置换术(TJR)后的毁灭性并发症，通常 重大的长期后果和发病率。每个人被诊断出多达100,000例骨科感染 在美国，这一数字预计将呈指数级增长。然而，问题的范围很广。 大一点。据报道，高达80%的患者在关节手术后持续疼痛，所有疼痛的骨科植入物 需要完整的评估以排除PJI的可能性。对感染的关注也是最重要的 TJR后患者到急诊科就诊的常见原因。不幸的是，使 感染的诊断仍然是一项重大挑战，特别是因为红斑和红斑等外在临床症状 肿胀，不是PJI所特有的。及时准确的诊断，避免不必要的过度治疗 对于良好的结果至关重要，特别是考虑到PJI管理通常需要多次手术和 延长住院时间。尽管如此，潜在的感染通常仍然没有被发现，因为 现有的诊断方法过时、缓慢且不精确。问题包括无法分离出传染性的 细菌(S)占20%-50%(培养阴性)，需要较长的孵育时间来分离某些病原体， 和较高的假阳性发生率。替代诊断工具也是有限的-要么是滑膜 必须将液体运送到中心实验室进行测试或过时的护理点(POC)诊断技术 必须仍然使用产生不太准确的二元结果(无论是否感染)的结果。那么，医生应该如何让 及时准确的诊断？我们团队是第一个发现滑液白细胞诊断价值的人 酯酶(LE)，一种由激活的中性粒细胞释放到细菌感染部位的抗微生物蛋白水解酶。 自从这一发现以来，医生一直在使用原始的LE‘Diptick’测试(Roche Chemstri®)来辅助PJI 诊断准确率高达89%左右，阴性预测值高达97%。 然而，最初设计用于尿液分析的测试在整形外科中广泛使用是不切实际的。 试纸是一种干燥的化学试剂垫，表面试剂在其中与样品中的酯酶反应，以 产生一种紫色的染料。临床医生根据测试垫上的颜色变化程度来读取结果。 不幸的是，缺乏客观性严重限制了其临床可靠性。关节液样本也必须进行离心法 试图清除可能扭曲结果的血液和碎片。我们突破性的LE测试是POC诊断 只需一小滴滑液即可快速定量测定LE的化验方法。结果是 仅需2分钟，即可通过移动应用程序提供给提供商，以推动临床决策。在第一阶段，我们 克服了重大挑战，交付了高度稳定的可用于生产的原型，没有信号漂移或 矩阵干扰，并设计了一种低成本的分析仪。我们的第二阶段目标是为规模化生产做准备 对生产的LE传感器和分析仪进行主验证，以建立产品声明以获得FDA的批准； 并进行多中心研究，以确定该设备在现场的真实诊断准确性。

Periprosthetic joint infection (PJI) is a devastating complication following total joint replacement (TJR) often with major long-term consequences and morbidity. As many as 100,000 orthopedic infections are diagnosed each year in the US, a number that is expected to rise exponentially. However, the scope of the problem is much larger. Persistent pain is reported in up to 80% of patients after joint surgery, and all painful orthopedic implants require a complete evaluation to rule out the possibility of PJI. Concern for infection is also the single most common reason for patients to present to the emergency department after TJR. Unfortunately, making the diagnosis of infection remains a major challenge, especially since outward clinical signs, such as erythema and swelling, are not specific to PJI. Immediate and accurate diagnoses that also avoid unnecessary overtreatment are critical for favorable outcomes, especially given that PJI management often requires multiple operations and prolonged hospitalization. Nevertheless, underlying infections still commonly go undetected due the nature of existing diagnostics, which are outdated, slow, and imprecise. Problems include the inability to isolate infectious organism(s) in 20-50% of cases (‘culture-negative’), long incubation times required to isolate certain pathogens, and the relatively high incidence of false positives. Alternative diagnostic tools are also limited – either synovial fluid must be transported to a central laboratory for testing or outdated point-of-care (POC) diagnostic technology must still be employed that yields less accurate, binary results (‘infected’ or not). So how should physicians make timely and accurate diagnoses? Our team was the first to discover the diagnostic value of synovial fluid leukocyte esterase (LE), an antimicrobial protease released by activated neutrophils recruited to sites of bacterial infection. Since that discovery, the original LE ‘dipstick’ test (Roche Chemstrip®) has been used by physician to aid in PJI diagnosis with a high diagnostic accuracy of about 89% and a negative predictive value as high as 97%. Nevertheless, the test in its original form designed for urinalysis is impractical for widespread use in orthopedics. The ‘dipstick’ is a dry chemical reagent pad, in which a surface reagent reacts with esterase in the sample to produce a purple dye. The result is read by a clinician based on the degree of color change on the test pad. Unfortunately, lack of objectivity severely limits its clinical reliability. Joint fluid samples must also be centrifuged in an attempt to remove blood and debris that can distort results. Our breakthrough LE test is a POC diagnostic assay that provides a rapid quantitative LE measurement with just a tiny droplet of synovial fluid. Results are immediately available to providers via a mobile app in just 2 minutes to drive clinical decisions. In Phase I, we overcame significant challenges and delivered a highly stable production-ready prototype without signal drift or matrix interference, and designed a low-cost analyzer. Our Phase II goals are to prepare for scale manufacturing of production LE sensors and analyzers, perform master validation to establish product claims for FDA clearance, and conduct a multi-center study to determine real-world diagnostic accuracy of the device in the field.