Pediatr Infect Dis J. 2018 Mar;37(3):206-211. doi: 10.1097/INF.0000000000001825.
Accurate diagnosis and appropriate treatment of group A streptococcal (GAS) pharyngitis are important to prevent complications. Most available rapid antigen detection tests (RADTs) have shown excellent specificity but often lack sensitivity. Our objective was to compare the diagnostic performances of a new fluorescence-based immunoassay and a classic immunochromatographic RADT using standard throat culture or polymerase chain reaction as references.
Prospective observational study in 2 pediatric emergency departments in children 3-15 years of age presenting with pharyngitis and a McIsaac score ≥2. Three throat swabs were obtained simultaneously: one for culture and one for each of both RADTs. Polymerase chain reaction assay of the DNaseB sequence was performed in case of discordant results (culture negative and either RADTs positive).
A total of 1002 patients were analyzed, with an overall 37.1% prevalence of GAS pharyngitis. Sensitivity, specificity, positive and negative predictive values were, respectively, 84.9%, 96.8%, 94.0% and 91.6% for the new fluorescence-based immunoassay, and 75.3%, 98.1%, 95.9% and 87.0% for the immunochromatographic test (*P < 0.05).
The immunofluorescence-based assay demonstrated improved diagnostic performances over the standard immunochromatographic RADT. Similarly specific for GAS detection, it demonstrates significantly higher sensitivity in children with McIsaac scores 2 or more. A negative result rules out a risk of GAS pharyngitis in 91.6% of children, making it an appropriate tool in pediatric emergency settings. Combined to the low incidence of rheumatic strains, critical appraisal of current practice to routinely perform a backup throat culture from children with pharyngitis and with negative GAS RADT could be reconsidered.
准确诊断和适当治疗 A 组链球菌（GAS）咽炎对于预防并发症很重要。大多数现有的快速抗原检测试验（RADTs）具有出色的特异性，但往往缺乏敏感性。我们的目的是比较一种新的荧光免疫测定法和一种经典的免疫层析 RADT 的诊断性能，以标准咽喉培养或聚合酶链反应作为参考。
在 2 家儿科急诊部门进行前瞻性观察研究，纳入年龄在 3-15 岁、咽炎且 McIsaac 评分≥2 的患儿。同时采集 3 个咽喉拭子：一个用于培养，另外两个用于两种 RADTs。如果结果不一致（培养阴性，而两种 RADTs 均阳性），则进行 DNaseB 序列的聚合酶链反应检测。
共分析了 1002 例患者，GAS 咽炎的总体患病率为 37.1%。新的荧光免疫测定法的敏感性、特异性、阳性预测值和阴性预测值分别为 84.9%、96.8%、94.0%和 91.6%，而免疫层析试验分别为 75.3%、98.1%、95.9%和 87.0%（*P<0.05）。
与标准免疫层析 RADT 相比，基于免疫荧光的检测方法具有更好的诊断性能。同样特异性地检测 GAS，在 McIsaac 评分≥2 的患儿中，其敏感性显著更高。阴性结果可排除 91.6%的患儿患 GAS 咽炎的风险，使其成为儿科急诊环境中的一种合适工具。鉴于风湿菌株的发生率较低，对目前常规进行咽部分泌物培养作为 GAS RADT 阴性患儿的后备治疗的做法可以进行重新评估。
