Department of Orthopaedic Surgery, Yokohama City University, Yokohama, Japan.
Department of Orthopaedic Surgery, Guangzhou University of Chinese Medicine, Guangzhou, China.
J Orthop Res. 2021 Feb;39(2):348-355. doi: 10.1002/jor.24959. Epub 2020 Dec 29.
Synovial fluid is important for the preoperative etiological diagnosis of suspected periprosthetic joint infection (PJI) or septic arthritis (SA). GENECUBE, an automated real-time polymerase chain reaction (PCR) assay, was used to detect bacterial mecA (methicillin resistance) and was compared with microbiological cultures for preoperatively diagnosing PJI and SA in 74 patients suspected of these infections and thus earmarked for surgery. PJI and SA were diagnosed in 21 and 6 cases, respectively, using modified ICM 2018 diagnostic criteria. Microbiological cultures determined methicillin-resistant staphylococcus (MRS) as the causative organism in six samples, which were all positive in the GENECUBE assay. Significantly also, the GENECUBE assay detected six MRS infections in culture-negative but infection-diagnosed patients, and in one inconclusive case, suggesting a higher sensitivity of this assay. Compared with microbiological culture, the sensitivity and specificity of the GENECUBE assay for mecAwas 100% and 92.2%, respectively. However, GENECUBE also produced invalid results in three cases, suggesting possible PCR inhibitors in the synovial fluid samples. We additionally validated the accuracy of pan-bacterial real-time PCR targeting 16S rRNA and other tests. Pan-bacterial real-time PCR was as effective as preoperative bacterial culture testing, although the α-defensin assay had the highest sensitivity at 100%. Hence, fully automated real-time PCR targeting of the bacterial mecA gene improves the etiological diagnosis of PJI and SA by reducing the testing time and lowering the false-positive detection rates. A screening approach for α-defensin followed by bacterial mecA gene testing in synovial fluids is therefore a more efficient method of preoperatively diagnosing PJI and SA.
滑液对于疑似人工关节周围感染（PJI）或化脓性关节炎（SA）的术前病因诊断非常重要。GENECUBE 是一种自动化实时聚合酶链反应（PCR）检测方法，用于检测细菌 mecA（耐甲氧西林），并与微生物培养进行比较，对 74 例疑似感染这些疾病并因此指定手术的患者进行术前 PJI 和 SA 的诊断。使用改良的 ICM 2018 诊断标准，分别在 21 例和 6 例患者中诊断为 PJI 和 SA。微生物培养确定耐甲氧西林金黄色葡萄球菌（MRS）为 6 个样本中的病原体，这 6 个样本在 GENECUBE 检测中均为阳性。同样重要的是，GENECUBE 检测在培养阴性但感染诊断的患者中检测到 6 例 MRS 感染，在 1 例不确定的病例中，提示该检测方法具有更高的灵敏度。与微生物培养相比，GENECUBE 检测 mecA 的灵敏度和特异性分别为 100%和 92.2%。然而，GENECUBE 也在 3 个病例中产生无效结果，提示滑液样本中可能存在 PCR 抑制剂。我们还验证了针对 16S rRNA 和其他测试的全细菌实时 PCR 的准确性。全细菌实时 PCR 与术前细菌培养测试一样有效，尽管α-防御素检测的灵敏度最高为 100%。因此，通过减少检测时间和降低假阳性检测率，针对细菌 mecA 基因的全自动实时 PCR 可提高 PJI 和 SA 的病因诊断。因此，在滑液中进行α-防御素筛选方法，然后进行细菌 mecA 基因检测，是一种更有效的术前诊断 PJI 和 SA 的方法。
