Van Tam T, Mestas Javier, Dien Bard Jennifer
Department of Pathology, Harbor-UCLA Medical Center, Torrance, CA.
Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, CA.
J Appl Lab Med. 2018 Nov 1;3(3):429-437. doi: 10.1373/jalm.2018.026104.
Group A Streptococcus (GAS) and large colony-forming group C (GCS) and G (GGS) β-hemolytic streptococci are important causes of acute pharyngitis in children and adults. Rapid and accurate diagnosis of streptococcal pharyngitis can improve patient care and potentially reduce transmission. In this study, we evaluated the performance of the Lyra Direct Strep (LDS) assay for detection of GAS and GCS/GGS compared with traditional culture methods.
Pharyngeal samples obtained from 278 children presenting to the emergency department with initial negative GAS rapid antigen detection test (RADT) were used. All samples were cultured as part of routine care and tested in batches using the LDS assay.
Of 278 pharyngeal samples with negative GAS RADT, 37 (13.3%) and 63 (22.7%) patients were positive for GAS by culture and LDS assay, respectively. Four (1.4%) patients were positive for GCS or GGS by culture or LDS assay. The LDS assay demonstrated sensitivity and specificity of 97.6% and 89.0%, respectively, compared with culture as the gold standard. Repeat culture and an alternate PCR showed that 85.7% (24 of 28) of discrepant samples agreed with findings of the LDS assay. Since implementation, the LDS assay shows a positivity rate of 21.0% (281 of 1340) compared with 11.7% (246 of 2110) by culture in the previous year.
We successfully implemented the LDS assay at our institution and have observed a significant increase in the positivity rate of GAS compared with culture. The LDS assay alone allowed for the elimination of β-streptococci screening by culture at our institution.
A 组链球菌（GAS）以及大菌落形成的 C 组（GCS）和 G 组（GGS）β溶血性链球菌是儿童和成人急性咽炎的重要病因。快速准确地诊断链球菌性咽炎可改善患者护理并有可能减少传播。在本研究中，我们评估了 Lyra 直接链球菌（LDS）检测法与传统培养方法相比在检测 GAS 和 GCS/GGS 方面的性能。
使用从 278 名因初始 GAS 快速抗原检测试验（RADT）呈阴性而到急诊科就诊的儿童获取的咽拭子样本。所有样本作为常规护理的一部分进行培养，并使用 LDS 检测法分批进行检测。
在 278 份 GAS RADT 呈阴性的咽拭子样本中，分别有 37 例（13.3%）和 63 例（22.7%）患者通过培养和 LDS 检测法检测出 GAS 呈阳性。4 例（1.4%）患者通过培养或 LDS 检测法检测出 GCS 或 GGS 呈阳性。以培养作为金标准，LDS 检测法的敏感性和特异性分别为 97.6%和 89.0%。重复培养和另一种聚合酶链反应显示，85.7%（28 份样本中的 24 份）的差异样本与 LDS 检测法的结果一致。自实施以来，LDS 检测法的阳性率为 21.0%（1340 份样本中的 281 份），而前一年培养法的阳性率为 11.7%（2110 份样本中的 246 份）。
我们在本机构成功实施了 LDS 检测法，并且观察到与培养法相比，GAS 的阳性率显著增加。仅 LDS 检测法就使得我们机构不再需要通过培养进行β溶血性链球菌筛查。
