Rubin Institute for Advanced Orthopedics, Center for Joint Preservation and Replacement, Sinai Hospital of Baltimore, West Belvedere Avenue, Baltimore, MD 21215, USA.
Int J Infect Dis. 2011 Oct;15(10):e702-5. doi: 10.1016/j.ijid.2011.05.015. Epub 2011 Jul 20.
The diagnosis of periprosthetic knee infections can present a challenge to surgeons, especially in the case of chronic presentation. Gram stains are regularly performed as part of the microbiological evaluation of suspected infected total knee arthroplasties. Recently, the utility of this test in diagnosing infections has been questioned. The purpose of this study was to assess the effectiveness of Gram stains performed from surgical site samples by comparing their results to the final diagnosis of infection.
The results of 347 Gram stains performed at a single center at the time of revision total knee arthroplasty for both septic and aseptic reasons were compared to the final diagnosis based on intra-operative findings and histological evaluation.
Gram staining demonstrated a low sensitivity of 7% (95% confidence interval 4-12%), a specificity of 99% (95% confidence interval 97-100%), and positive and negative predictive values of 92% and 57%, respectively.
This study confirmed previous findings of the poor utility of this test for the diagnosis of periprosthetic knee infections. The authors recommend that Gram staining no longer be performed at the time of suspected periprosthetic knee arthroplasty infection.
假体周围膝关节感染的诊断对外科医生来说是一个挑战，尤其是在慢性表现的情况下。革兰氏染色作为疑似感染性全膝关节置换术的微生物学评估的一部分经常进行。最近，该测试在诊断感染方面的效用受到质疑。本研究旨在通过将革兰氏染色结果与感染的最终诊断进行比较，评估手术部位样本进行革兰氏染色的效果。
对单中心因感染和非感染原因进行的 347 例全膝关节翻修术中的革兰氏染色结果进行了比较，最终诊断基于术中发现和组织学评估。
革兰氏染色显示出较低的灵敏度为 7%（95%置信区间 4-12%），特异性为 99%（95%置信区间 97-100%），阳性和阴性预测值分别为 92%和 57%。
本研究证实了先前关于该测试在诊断假体周围膝关节感染方面效用不佳的发现。作者建议在疑似假体周围膝关节感染时不再进行革兰氏染色。
