Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
J Clin Microbiol. 2018 Apr 25;56(5). doi: 10.1128/JCM.01874-17. Print 2018 May.
The lack of reliable diagnostic tests for detecting vaccine serotype pneumococcal pneumonia (VTPP) remains a challenging issue in pneumococcal vaccine studies. This study assessed the performances of high-throughput nanofluidic PCR-based pneumococcal serotyping and quantification assay methods using sputum samples (the nanofluidic sputum quantitative PCR [Sp-qPCR] assay) to diagnose 13-valent pneumococcal conjugate VTPP compared with the performance of the serotype-specific urinary antigen detection (UAD) assay using urine samples. Adult pneumonia patients from Japan were enrolled in this study between September 2012 and August 2014. Sputum samples were subjected to the nanofluidic Sp-qPCR assay, quantitatively cultured, and serotyped by the Quellung reaction (SpQt). Urine samples were tested by the UAD method. The diagnostic performances of these tests were assessed using composite reference standards and Bayesian latent class models (BLCMs). Among 244 total patients, 27 (11.1%) tested positive with the UAD assay, while 16 (6.6%) and 34 (13.9%) tested positive with the SpQt and nanofluidic Sp-qPCR assays, respectively, with a cutoff value of ≥10 DNA copies/ml, which showed the maximum value of the Youden index. Using BLCMs, the estimated prevalence for VTPP was 12.9%, and the nanofluidic Sp-qPCR assay demonstrated the best performance (sensitivity, 90.2%; specificity, 96.9%), followed by UAD (sensitivity, 75.6%; specificity, 97.9%) and SpQt (sensitivity, 45.8%; specificity, 99.5%). However, when a higher cutoff value of ≥10 DNA copies/ml was applied, the performance of UAD became comparable to that of Sp-qPCR. The vaccine serotype-specific pneumococcal DNA load in sputum among UAD-positive patients was 3 logs higher than that among UAD-negative patients ( = 0.036). The nanofluidic Sp-qPCR assay may be accurate and useful for detecting VTPP among adults.
用于检测疫苗血清型肺炎球菌性肺炎（VTPP）的可靠诊断测试仍然是肺炎球菌疫苗研究中的一个具有挑战性的问题。本研究评估了使用痰液样本的高通量基于纳米流控 PCR 的肺炎球菌血清分型和定量检测方法（纳米流控痰液定量 PCR [Sp-qPCR] 检测）与使用尿液样本的血清型特异性尿抗原检测（UAD）检测方法相比，用于诊断 13 价肺炎球菌结合疫苗 VTPP 的性能。本研究于 2012 年 9 月至 2014 年 8 月期间纳入了来自日本的成年肺炎患者。对痰液样本进行纳米流控 Sp-qPCR 检测、定量培养，并通过 Quellung 反应（SpQt）进行血清分型。尿液样本采用 UAD 方法进行检测。使用复合参考标准和贝叶斯潜在类别模型（BLCMs）评估这些检测方法的诊断性能。在 244 例患者中，27 例（11.1%）UAD 检测阳性，16 例（6.6%）和 34 例（13.9%）SpQt 和纳米流控 Sp-qPCR 检测阳性，其截断值为≥10 拷贝/ml，具有最大的 Youden 指数值。使用 BLCMs 估计 VTPP 的流行率为 12.9%，纳米流控 Sp-qPCR 检测的性能最佳（敏感性 90.2%，特异性 96.9%），其次是 UAD（敏感性 75.6%，特异性 97.9%）和 SpQt（敏感性 45.8%，特异性 99.5%）。然而，当应用更高的截断值≥10 拷贝/ml 时，UAD 的性能可与 Sp-qPCR 相媲美。UAD 阳性患者的痰中疫苗血清型特异性肺炎球菌 DNA 载量比 UAD 阴性患者高 3 个对数级（=0.036）。纳米流控 Sp-qPCR 检测可能是一种准确且有用的方法，可用于检测成年人群中的 VTPP。
