Castañeda-Torres Maria Camila, Arango Julián, Zuluaga Alejandra, Rúa-Giraldo Álvaro, Caceres Diego H
Medical and Experimental Mycology Group, Corporation for Biological Research (CIB-UdeA-UPB-UDES), Medellín, Colombia.
School of microbiology, Universidad de Antioquia, Medellín, Colombia.
Med Mycol. 2024 Dec 27;63(1). doi: 10.1093/mmy/myae116.
Cryptococcosis predominantly affects immunocompromised individuals, particularly those with advanced HIV disease, with meningitis being the most severe form and linked to high mortality. Diagnosis typically relies on rapid Cryptococcus antigen (CrAg) testing, and antigen titer quantification helps in early detection and assessing disease severity. However, conventional titer methods are often more expensive than qualitative antigen detection. This study assessed the diagnostic performance of a semi-quantitative lateral flow assay (CrAgSQ LFA, IMMY™) for CrAg detection in serum and cerebrospinal fluid (CSF) collected between 2014 and 2022. The CrAgSQ LFA was compared to the standard CrAg LFA (IMMY™) and Clarus Cryptococcal Ag enzyme immunoassay (EIA-CrAg, IMMY™). The CrAgSQ LFA demonstrated 100% sensitivity and specificity in both serum and CSF, with perfect agreement (kappa 1.00) with the CrAg LFA. When comparing the CrAgSQ LFA with the titer measurement results obtained using CrAg LFA, titers ranged as follows: in category 1+, from 1:2 to 1:20; in 2+, from 1:5 to 1:40; in 3+, from 1:20 to 1:2560; and in 4+, from 1:320 to 1:2560. Titer results for the CrAgSQ LFA aligned well with CrAg LFA, and operator agreement was strong, with weighted kappa values of 0.926 and 0.966. The CrAg-EIA showed a sensitivity of 84% and specificity of 100% using the manufacture cutoff (>0.265), which improved to 96% sensitivity with an optimized cutoff value (>0.145). Overall, the CrAgSQ LFA demonstrated high accuracy and reliability, suggesting it could be a valuable tool for diagnosing cryptococcosis in the Americas.
隐球菌病主要影响免疫功能低下的个体，尤其是那些患有晚期艾滋病的患者，脑膜炎是最严重的形式，且与高死亡率相关。诊断通常依赖于快速隐球菌抗原（CrAg）检测，抗原滴度定量有助于早期检测和评估疾病严重程度。然而，传统的滴度检测方法通常比定性抗原检测更昂贵。本研究评估了一种半定量侧向流动分析法（CrAgSQ LFA，IMMY™）在检测2014年至2022年期间收集的血清和脑脊液（CSF）中CrAg的诊断性能。将CrAgSQ LFA与标准CrAg LFA（IMMY™）和Clarus隐球菌抗原酶免疫测定法（EIA-CrAg，IMMY™）进行比较。CrAgSQ LFA在血清和脑脊液中均表现出100%的灵敏度和特异性，与CrAg LFA完全一致（kappa值为1.00）。当将CrAgSQ LFA与使用CrAg LFA获得的滴度测量结果进行比较时，滴度范围如下：1+类别中，为1:2至1:20；2+类别中，为1:5至1:40；3+类别中，为1:20至1:2560；4+类别中，为1:320至1:2560。CrAgSQ LFA的滴度结果与CrAg LFA吻合良好，且操作人员之间的一致性很强，加权kappa值分别为0.926和0.966。使用制造商设定的临界值（>0.265）时，CrAg-EIA的灵敏度为84%，特异性为100%，优化临界值（>0.145）后灵敏度提高至96%。总体而言，CrAgSQ LFA显示出高准确性和可靠性，表明它可能是美洲地区诊断隐球菌病的一种有价值的工具。
