Dubbels Marie, Granger Dane, Theel Elitza S
Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA.
Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
J Clin Microbiol. 2017 Aug;55(8):2472-2479. doi: 10.1128/JCM.00751-17. Epub 2017 May 31.
Detection of antigen (CrAg) is invaluable for establishing cryptococcal disease. Multiple different methods for CrAg detection are available, including a lateral flow assay (LFA). Despite excellent performance of the CrAg LFA, we have observed multiple cases of low-titer (≤1:5) positive CrAg LFA results in patients for whom cryptococcosis was ultimately excluded. To investigate the accuracy of low-titer positive CrAg LFA results, we performed chart reviews for all patients with positive CrAg LFA results between June 2014 and December 2016. During this period, serum and/or cerebrospinal fluid (CSF) samples from 3,969 patients were tested with the CrAg LFA, and 55 patients (1.5%) tested positive. Thirty-eight of those patients lacked a history of cryptococcal disease and were the focus of this study. Fungal culture or histopathology confirmed infection for 20 patients (52.6%), and CrAg LFA titers in serum and CSF samples ranged from 1:5 to ≥1:2,560. For the 18 patients (47.4%) without culture or histopathological confirmation, the CrAg LFA results were considered true-positive results for 5 patients (titer range, 1:10 to ≥1:2,560), due to clinical improvement with targeted therapy and decreasing CrAg LFA titers. The remaining 13 patients had CrAg LFA titers of 1:2 ( = 11) or 1:5 ( = 2) and were ultimately diagnosed with an alternative condition ( = 11) or began therapy for possible cryptococcosis without improvement ( = 2), leading to an overall CrAg LFA false-positive rate of 34%. We recommend careful clinical correlation prior to establishing a diagnosis of cryptococcal infection for patients with first-time positive CrAg LFA titers of 1:2.
检测隐球菌抗原(CrAg)对于确诊隐球菌病非常重要。目前有多种不同的CrAg检测方法,包括侧向流动分析法(LFA)。尽管CrAg LFA表现出色,但我们观察到多例CrAg LFA低滴度(≤1:5)阳性结果的患者,最终被排除患有隐球菌病。为了研究CrAg LFA低滴度阳性结果的准确性,我们对2014年6月至2016年12月期间所有CrAg LFA检测结果呈阳性的患者进行了病历回顾。在此期间,对3969例患者的血清和/或脑脊液(CSF)样本进行了CrAg LFA检测,其中55例(1.5%)检测呈阳性。这些患者中有38例没有隐球菌病病史,是本研究的重点。真菌培养或组织病理学证实20例患者(52.6%)感染,血清和脑脊液样本中的CrAg LFA滴度范围为1:5至≥1:2560。对于18例(47.4%)未通过培养或组织病理学确诊的患者,由于针对性治疗后临床症状改善且CrAg LFA滴度降低,5例患者(滴度范围为1:10至≥1:2560)的CrAg LFA结果被视为真阳性结果。其余13例患者的CrAg LFA滴度为1:2(n = 11)或1:5(n = 2),最终被诊断为其他疾病(n = 11)或开始接受可能的隐球菌病治疗但无改善(n = 2),导致CrAg LFA总体假阳性率为34%。对于首次CrAg LFA滴度为1:2呈阳性的患者,我们建议在诊断隐球菌感染之前进行仔细的临床关联分析。