Centre for Infectious Diseases and Microbiology Laboratory Services, Westmead Hospital, Westmead, New South Wales, Australia.
PLoS One. 2012;7(11):e49541. doi: 10.1371/journal.pone.0049541. Epub 2012 Nov 14.
Cryptococcus neoformans causes life-threatening meningitis. A recently introduced lateral flow immunoassay (LFA) to detect cryptococcal antigen (CRAG) is reportedly more rapid and convenient than standard latex agglutination (LA), but has not yet been evaluated in a diagnostic laboratory setting.
One hundred and six serum, 42 cerebrospinal fluid (CSF), and 20 urine samples from 92 patients with known or suspected cryptococcosis were tested by LA and LFA, and titres were compared. Results were correlated with laboratory-confirmed cryptococcosis. Serial samples were tested in nine treated patients.
Twenty-five of 92 patients had confirmed cryptococcosis; all sera (n = 56) from these patients were positive by LFA (sensitivity 100%, 95% confidence interval (CI) 93.6-100%) compared with 51/56 positive by LA (sensitivity 91.1%, 95% CI 80.7-96.1%). Fifty sera from 67 patients without cryptococcosis tested negative in both assays. While LA yielded more false negative results (5/56) this did not reach statistical significance (p = 0.063). Nine CSF samples from patients with cryptococcal meningitis yielded positive results using both assays while 17/18 urine samples from patients with cryptococcosis were positive by the LFA. The LFA detected CRAG in C. gattii infection (n = 4 patients). Agreement between titres obtained by both methods (n = 38 samples) was imperfect; correlation between log-transformed titres (r) was 0.84. Turn-around-time was 20 minutes for the LFA and 2 h for LA. The cost per qualitative sample was 18USD and 91 USD, respectively and per quantitative sample was 38USD and 144USD, respectively.
Qualitative agreement between the LFA and LA assays performed on serum and CSF was good but agreement between titres was imperfect. Ease of performance of the LFA and the capacity for testing urine suggest it has a role in the routine laboratory as a rapid diagnostic test or point-of-care test.
新型隐球菌可引起危及生命的脑膜炎。最近推出的侧向流动免疫分析（LFA）检测隐球菌抗原（CRAG）据称比标准乳胶凝集（LA）更快、更方便，但尚未在诊断实验室环境中进行评估。
对 92 例已知或疑似隐球菌病患者的 106 份血清、42 份脑脊液（CSF）和 20 份尿液样本进行 LA 和 LFA 检测，并比较滴度。结果与实验室确诊的隐球菌病相关。对 9 例接受治疗的患者进行了连续样本检测。
92 例患者中有 25 例确诊为隐球菌病；这些患者的所有血清（n=56）均通过 LFA 呈阳性（敏感性 100%，95%置信区间（CI）93.6-100%），而 51/56 通过 LA 呈阳性（敏感性 91.1%，95%CI 80.7-96.1%）。67 例无隐球菌病患者的 50 份血清在两种检测中均呈阴性。虽然 LA 产生了更多的假阴性结果（5/56），但这并没有达到统计学意义（p=0.063）。两种检测均从 9 例隐球菌性脑膜炎患者的脑脊液样本中获得阳性结果，而 18 例隐球菌病患者的 17 份尿液样本通过 LFA 呈阳性。LFA 检测到 C. gattii 感染（n=4 例）。两种方法（n=38 份样本）获得的滴度之间的一致性不理想；对数转换滴度（r）的相关性为 0.84。LFA 的周转时间为 20 分钟，LA 为 2 小时。定性样本的每个样本成本分别为 18 美元和 91 美元，定量样本的每个样本成本分别为 38 美元和 144 美元。
血清和 CSF 中 LFA 和 LA 检测的定性一致性良好，但滴度的一致性不理想。LFA 易于操作且可用于检测尿液，表明其在常规实验室中作为快速诊断测试或即时检测具有一定的作用。
