Smith Charlotte, Maloney Robert J, Wearmouth Deborah, Sharma Hemant, Saeed Kordo, Ahmad-Saeed Nusreen, Annett Rachel, Barrett Lucinda, Boyd Sara E, Davies Peter, Hughes Harriet, Jones Gwennan, Leach Laura, Lynch Maureen, Nayar Deepa, Marsh Martin, Mitchell Shanine, Moffat Lynn, Moore Luke S P, Murphy Michael E, O'Shea Shaan Ashk, Peach Teresa, Petridou Christina, Reidy Niamh, Talbot Ben, Aldridge Catherine, Barlow Gavin
Sheffield Health & Social Care NHS Foundation Trust, Centre Court, Atlas Way, Sheffield, S4 7QQ, UK.
Department of Infection, Hull University Teaching Hospitals NHS Trust, Hull, UK.
J Bone Jt Infect. 2025 Mar 17;10(2):61-71. doi: 10.5194/jbji-10-61-2025. eCollection 2025.
: Gram stain of synovial fluid is a rapid test for the diagnosis of native joint septic arthritis. Single-centre studies have suggested Gram stain will miss a considerable proportion of patients who are subsequently synovial-fluid-culture-positive or polymerase chain reaction (PCR)-positive. The object of this study was to reassess Gram stain in a large, multi-centre cohort of patients from the United Kingdom (UK) and Ireland. : The study was a retrospective analysis combining two large datasets. We defined septic arthritis microbiologically as at least one positive joint aspirate culture and/or PCR test. "Best case" and "worst case" definitions were applied depending on the likelihood organisms were true infecting pathogens. : Gram stain missed a high proportion of culture-/PCR-positive patients using both the best (74 % missed) and worst (81 % missed) case definitions. Using the best case definition, the sensitivity of Gram stain was 0.26, specificity 0.99, positive predictive value 0.84, negative predictive value 0.87, accuracy 0.87, and area under the receiver operator curve 0.62 (95 % CI 0.57 to 0.68, ). False positive Gram stains were infrequent (1 %). Age, joint involved, and other synovial fluid characteristics were less predictive of a positive culture/PCR than Gram stain. : While a positive synovial fluid Gram stain should always be considered to indicate potential septic arthritis, a negative Gram stain, regardless of synovial fluid crystals or white cell count, should not be used to rule out septic arthritis. The value of Gram stain as an urgent out-of-hours test for septic arthritis is open to considerable debate.
滑膜液革兰氏染色是诊断原发性关节化脓性关节炎的快速检测方法。单中心研究表明，革兰氏染色会遗漏相当一部分随后滑膜液培养阳性或聚合酶链反应（PCR）阳性的患者。本研究的目的是在来自英国和爱尔兰的大型多中心患者队列中重新评估革兰氏染色。：该研究是一项结合两个大型数据集的回顾性分析。我们将化脓性关节炎在微生物学上定义为至少一次关节穿刺培养和/或PCR检测呈阳性。根据生物体为真正感染病原体的可能性应用“最佳情况”和“最差情况”定义。：无论采用最佳情况定义（遗漏74%）还是最差情况定义（遗漏81%），革兰氏染色都遗漏了很大比例的培养/PCR阳性患者。采用最佳情况定义时，革兰氏染色的敏感性为0.26，特异性为0.99，阳性预测值为0.84，阴性预测值为0.87，准确性为0.87，受试者操作特征曲线下面积为0.62（95%CI 0.57至0.68）。革兰氏染色假阳性很少见（1%）。年龄、受累关节和其他滑膜液特征对培养/PCR阳性的预测性低于革兰氏染色。：虽然滑膜液革兰氏染色阳性应始终被视为提示潜在的化脓性关节炎，但革兰氏染色阴性，无论滑膜液晶体或白细胞计数如何，都不应被用于排除化脓性关节炎。革兰氏染色作为化脓性关节炎的紧急非工作时间检测方法的价值存在很大争议。
