Background: 

Antigen immunoassays to detect synovial fluid (SF) microorganisms have recently been made available for clinical use. The purpose of this study was to determine the sensitivity and specificity of an SF microorganism antigen immunoassay detection (MID) panel, evaluate the panel’s capability to detect microorganisms in the setting of culture-negative periprosthetic joint infection (PJI), and determine diagnostic predictive values of the MID panel for PJI.

Methods: 

This study included 67,441 SF samples obtained from a hip or knee arthroplasty, from 2,365 institutions across the United States, submitted to 1 laboratory for diagnostic testing. All data were prospectively compiled and then were analyzed retrospectively. Preoperative SF data were used to classify each specimen by the International Consensus Meeting (2018 ICM) definition of PJI: 49,991 were not infected, 5,071 were inconclusive, and 12,379 were infected. The MID panel, including immunoassay tests to detect Staphylococcus, Candida, and Enterococcus, was evaluated to determine its diagnostic performance.

Results: 

The MID panel demonstrated a sensitivity of 94.2% for infected samples that yielded positive cultures for target microorganisms (Staphylococcus, Candida, or Enterococcus). Among infected samples yielding positive cultures for their respective microorganism, individual immunoassay test sensitivity was 93.0% for Staphylococcus, 92.3% for Candida, and 97.2% for Enterococcus. The specificity of the MID panel for samples that were not infected was 98.4%, yielding a false-positive rate of 1.6%. The MID panel detected microorganisms among 49.3% of SF culture-negative infected samples. For PJI as a diagnosis, the positive predictive value of the MID panel was 91.7% and the negative predictive value was 93.8%. Among MID-positive PJIs, 16.2% yielded a discordant cultured organism instead of that detected by the antigen test.

Conclusions: 

SF microorganism antigen testing provides a timely adjunct method to detect microorganisms in the preoperative SF aspirate, yielding a low false-positive rate and enabling the detection of a microorganism in nearly one-half of SF culture-negative PJIs.

Level of Evidence: 

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

中文翻译：

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作为术前滑液分析组成部分的微生物抗原检测的全国结果

背景： 

用于检测滑液 (SF) 微生物的抗原免疫测定最近已可用于临床。本研究的目的是确定 SF 微生物抗原免疫检测 (MID) 面板的灵敏度和特异性，评估面板在培养阴性假体周围关节感染 (PJI) 的情况下检测微生物的能力，并确定诊断预测值PJI 的 MID 面板。

方法： 

该研究包括从全美 2,365 家机构的髋关节或膝关节置换术中获得的 67,441 份 SF 样本，这些样本提交给 1 个实验室进行诊断测试。所有数据都是前瞻性编制的，然后进行回顾性分析。根据国际共识会议 (2018 ICM) 对 PJI 的定义，使用术前 SF 数据对每个标本进行分类：49,991 例未感染，5,071 例不确定，12,379 例感染。MID 面板，包括用于检测葡萄球菌、念珠菌和肠球菌的免疫测定测试，经过评估以确定其诊断性能。

结果： 

MID 面板显示对目标微生物（葡萄球菌、念珠菌或肠球菌）培养呈阳性的感染样品的灵敏度为 94.2%。在各自微生物培养呈阳性的感染样本中，葡萄球菌的个体免疫检测灵敏度为 93.0%，念珠菌为 92.3%，肠球菌为 97.2%。MID panel 对未感染样本的特异性为 98.4%，假阳性率为 1.6%。MID 面板在 49.3% 的 SF 培养阴性感染样本中检测到微生物。对于 PJI 作为诊断，MID 面板的阳性预测值为 91.7%，阴性预测值为 93.8%。在 MID 阳性 PJI 中，16.2% 产生了不一致的培养生物，而不是抗原测试检测到的生物。

结论： 

SF 微生物抗原检测提供了一种及时的辅助方法来检测术前 SF 抽吸物中的微生物，假阳性率低，并且能够在近一半的 SF 培养阴性 PJI 中检测到微生物。

证据等级： 

预后二级。有关证据等级的完整描述，请参阅作者须知。