脊柱化脓性感染模型犬感染的判断与植入物治疗

背景：应用生物发光基因标记细菌建立动物感染模型，模拟脊柱感染的局部环境，揭示脊柱感染发生的病理生理机制。 目的：探讨前路一期清创自体髂骨植骨钛板内固定治疗脊柱化脓性感染的可行性及安全性。 方法：取中国家犬24只，用生物发光基因标记金葡菌Xen29建立犬脊柱化脓性感染模型。应用X射线、CT、MRI等检查对模型进行系统的动态影像学观察。建模4周后所有犬行前路一期清创自体髂骨植骨钛板内固定。内固定中、内固定后连续4周应用抗生素抗感染治疗。分别于内固定后4，8，12，24周处死犬，将钛板及钛板比邻的骨组织取出，进行传统的细菌培养、普通细菌16S rRNA 基因及金葡菌特异性Nuc基因进行PCR检测、生物发光成像(BLI)检测。 结果与结论：家犬内固定后观察切口愈合良好，没有窦道形成及脓性物质渗出。标本大体观察及MRI检查结果均未见脓肿形成、椎骨骨髓炎等感染复发征象。用传统的细菌培养、普通细菌16S rRNA 基因PCR检测作为判断感染与否的标准，感染率分别为41.7%(10/24)、75%(18/24)，表明用PCR检测细菌16S rRNA 基因的检测方法判断感染的敏感性要明显高于传统细菌培养方法(P < 0.05)。金黄色葡萄球菌特异性Nuc基因的PCR检测验证有金黄色葡萄球菌存在(1/24)。而利用BLI技术对假体周围细菌进行特异性基因检测，并未检出基因标记的细菌Xen29(0/24)。证实体内假体上细菌附着是一种相对的普遍现象，并且内固定后取出的假体上分离出来的细菌与内固定前脊柱所感染的细菌种类并非同源。提示前路一期清创自体髂骨植骨钛板内固定治疗脊柱化脓性感染是安全有效的。内固定的使用不会造成感染复发或持续性慢性感染。 中国组织工程研究杂志出版内容重点：肾移植；肝移植；移植；心脏移植；组织移植；皮肤移植；皮瓣移植；血管移植；器官移植；组织工程全文链接：

Criteria and implant treatment for pyogenic spinal infection in dogs

BACKGROUND:Animal model of infection is established using bioluminescent gene-labeled bacteria, which stimulate local environment of spine infection and reveal the pathophysiological mechanism of spine infection. OBJECTIVE:To evaluate the feasibility and safety of anterior one-stage debridement, autogenous iliac bone grafting and titanium plate internal fixation in the management of pyogenic spinal infections in spine. METHODS:Totally 24 Chinese dogs were adopted in the study to develop a canine model of acute pyogenic spondylodiscitis using a bioluminescent strain of Staphylococcus aureus Xen29. The animal models were detected by X-radiography, CT and MRI examinations. After 4 weeks of modeling, all the animals underwent one-stage debridement, autogenous iliac bone grafting and anterior titanium plate internal fixation. Antibiotics  contained Cefazolin and Gentamicin were administrated daily since perioperative period to 4 weeks after surgery. The titanium plate and adjacent vertebra were removed surgically at various postoperative time points (4, 8, 12, 24 weeks) when the dogs were killed. The excised tissues and retrieved implants were cultured with conventional bacteria, bacteria 16S rRNA and specific Nuc gene of Staphylococcus aureus. PCR and bioluminescence imaging technique were used to detect the presence of bacteria. RESULTS AND CONCLUSION:The surgical wound was healed uneventfully. Gross observation and MRI examination of the specimens showed that there was no abscess formation or signs of infection recurrence. The infection rate was 41.7% (10/24) and 75% (18/24) in the procedure of conventional bacteria and bacteria 16S rRNA cultivation. The results showed that the sensibility of PCR technique used to detect the presence of bacteria by amplifying the highly conservative gene sequence of 16S rRNA was significantly higher than that of conventional bacterial cultivation procedure (P < 0.05). The PCR detection of specific Nuc gene of Staphylococcus aureus showed the existence of Staphylococcus aureus (1/24). However, Staphylococcus aureus Xen29 with genetic marker was not detected around the implant by bioluminescence imaging technique (0/24). All of the results showed that bacterium adhering to prosthesis in vivo is an universal phenomenon. The bacteria identified from prosthesis which was taken during the surgery and the bacteria by which the spine was infected before the surgery was not homologous. The one-stage debridement, autogenous bone grafting and anterior titanium plate internal fixation is safe and effective in the management of pyogenic spinal infections. Using of internal fixator can not lead to recurrence or persistence of infection.