Austere Environments Consortium for Enhanced Sepsis Outcomes, Biological Defense Research Directorate, Naval Medical Research Center-Frederick, Ft. Detrick.
Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland.
Clin Infect Dis. 2019 Jul 18;69(3):421-427. doi: 10.1093/cid/ciy929.
Infection with the gram-negative bacterium Burkholderia pseudomallei can result in melioidosis, a life-threatening disease that can be difficult to diagnose. Culture remains the gold standard for diagnosis but requires laboratory resources not available in many endemic regions. A lateral flow immunoassay has shown promise for POC diagnostics but suffers from low sensitivity when used on blood samples. PCR also has low sensitivity on blood, attributed to the low bacterial numbers in blood observed in melioidosis patients, even when bacteraemic.
A prototype i-STAT cartridge was developed to utilize the monoclonal antibody specific for the capsule of pathogenic Burkholderia species employed on the LFI. The resulting POC assay was evaluated on 414 clinical specimens from Darwin, Australia and Cambodia.
The i-STAT assay accurately distinguished Australian blood culture positive melioidosis patients from Australian patients hospitalized with other infections (AUC = 0.91, 95% CI 0.817 - 1.0). We derived an assay cutoff with 76% sensitivity and 94% specificity that correctly classified 88% (n = 74) of the Australian patients. Interestingly, only 46% (6/13) of the culture-positive melioidosis patients in Cambodia were classified correctly. Of great importance however, the assay detected capsule from blood samples for 32% of blood culture negative melioidosis patients in both cohorts and previously undiagnosed melioidosis patients in Cambodia. In addition the assay showed high sensitivity and specificity for urine, pus and sputum.
Diagnostic tools that are not dependent upon the growth kinetics or the levels of bacteremia of B. pseudomallei represent the next-generation of diagnostics and must be pursued further.
感染革兰氏阴性细菌伯克霍尔德菌假单胞菌可导致类鼻疽病，这是一种危及生命的疾病，难以诊断。培养仍然是诊断的金标准，但需要实验室资源，而许多流行地区都没有这些资源。侧向流动免疫测定法已显示出用于 POCT 诊断的潜力，但在使用血液样本时敏感性较低。PCR 在血液中的敏感性也较低，这归因于即使在菌血症时，类鼻疽病患者血液中的细菌数量也较低。
开发了一种原型 i-STAT 试剂盒，以利用针对致病性伯克霍尔德菌属荚膜的单克隆抗体，该抗体用于 LFI。对来自澳大利亚达尔文和柬埔寨的 414 份临床标本进行了评估。
i-STAT 检测法准确地区分了澳大利亚血培养阳性的类鼻疽病患者和因其他感染住院的澳大利亚患者（AUC = 0.91，95%CI 0.817-1.0）。我们得出了一个检测截止值，具有 76%的敏感性和 94%的特异性，正确分类了 88%（n=74）的澳大利亚患者。有趣的是，在柬埔寨，只有 46%（6/13）的培养阳性类鼻疽病患者被正确分类。然而，非常重要的是，该检测法在两个队列的 32%血培养阴性的类鼻疽病患者和柬埔寨以前未被诊断的类鼻疽病患者的血液样本中检测到荚膜。此外，该检测法对尿液、脓液和痰液具有很高的敏感性和特异性。
不依赖于伯克霍尔德菌假单胞菌生长动力学或菌血症水平的诊断工具代表了下一代诊断工具，必须进一步研究。
