Orthopaedic Hospital Research Center, Orthopaedic Hospital Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California, Los Angeles (UCLA), USA.
J Orthop Res. 2012 Mar;30(3):335-40. doi: 10.1002/jor.21519. Epub 2011 Aug 11.
Post-arthroplasty infections are a devastating problem in orthopaedic surgery. While acute infections can be treated with a single stage washout and liner exchange, chronic infections lead to multiple reoperations, prolonged antibiotic courses, extended disability, and worse clinical outcomes. Unlike previous mouse models that studied an acute infection, this work aimed to develop a model of a chronic post-arthroplasty infection. To achieve this, a stainless steel implant in the knee joints of mice was inoculated with a bioluminescent Staphylococcus aureus strain (1 × 10(2) -1 × 10(4) colony forming units, CFUs) and in vivo imaging was used to monitor the bacterial burden for 42 days. Four different S. aureus strains were compared in which the bioluminescent construct was integrated in an antibiotic selection plasmid (ALC2906), the bacterial chromosome (Xen29 and Xen40), or a stable plasmid (Xen36). ALC2906 had increased bioluminescent signals through day 10, after which the signals became undetectable. In contrast, Xen29, Xen40, and Xen36 had increased bioluminescent signals through 42 days with the highest signals observed with Xen36. ALC2906, Xen29, and Xen40 induced significantly more inflammation than Xen36 as measured by in vivo enhanced green fluorescence protein (EGFP)-neutrophil flourescence of LysEGFP mice. All four strains induced comparable biofilm formation as determined by variable-pressure scanning electron microscopy. Using a titanium implant, Xen36 had higher in vivo bioluminescence signals than Xen40 but had similar biofilm formation and adherent bacteria. In conclusion, Xen29, Xen40, and especially Xen36, which had stable bioluminescent constructs, are feasible for long-term in vivo monitoring of bacterial burden and biofilm formation to study chronic post-arthroplasty infections and potential antimicrobial interventions.
关节置换术后感染是骨科手术中的一个严重问题。虽然急性感染可以通过单次冲洗和衬垫更换来治疗，但慢性感染会导致多次手术、延长抗生素疗程、延长残疾时间，并导致更差的临床结果。与之前研究急性感染的小鼠模型不同，这项工作旨在开发一种慢性关节置换术后感染模型。为此，将发光的金黄色葡萄球菌菌株（1×10(2) -1×10(4) 菌落形成单位，CFU）接种到小鼠膝关节的不锈钢植入物中，并使用体内成像技术监测细菌负荷 42 天。比较了四种不同的金黄色葡萄球菌菌株，其中发光构建体整合在抗生素选择质粒（ALC2906）、细菌染色体（Xen29 和 Xen40）或稳定质粒（Xen36）中。ALC2906 在第 10 天之前具有增加的生物发光信号，此后信号变得无法检测。相比之下，Xen29、Xen40 和 Xen36 直到第 42 天仍具有增加的生物发光信号，其中 Xen36 的信号最高。与 Xen36 相比，ALC2906、Xen29 和 Xen40 引起的炎症反应明显更多，这是通过 LysEGFP 小鼠体内增强型绿色荧光蛋白（EGFP）-中性粒细胞荧光来衡量的。所有四种菌株通过可变压力扫描电子显微镜确定的生物膜形成相似。使用钛植入物，Xen36 在体内的生物发光信号高于 Xen40，但生物膜形成和附着细菌相似。总之，Xen29、Xen40 尤其是 Xen36，其具有稳定的生物发光构建体，可用于长期体内监测细菌负荷和生物膜形成，以研究慢性关节置换术后感染和潜在的抗菌干预措施。
