Ofluoglu Ender Ali, Zileli Mehmet, Aydin Derya, Baris Yakup Sancar, Kuçukbasmaci Omer, Gonullu Nevriye, Ofluoglu Onder, Toplamaoglu Halil
Department of Neurosurgery, Bakirkoy Hospital for Psychiatric and Neurological Diseases, Istanbul, Turkey.
Arch Orthop Trauma Surg. 2007 Jul;127(5):391-6. doi: 10.1007/s00402-007-0365-0. Epub 2007 May 24.
The rate of postoperative infections is approximately 1% in spine surgery. However, when metal implants are used, postoperative infection rates significantly increase and were reported between 2.1 and 8.5%. This study aim to set up an infection model in the rat spine with a metal implant.
Forty white male Sprague Dawley rats were randomly divided in four groups. In all rats, under operation microscope, a 3 mm titanium microscrew was implanted in the thoracolumbar area (T10-L1) after laminar decortication. In Group I (control group), sterile isotonic solution and in other three groups, different concentrations of Staphylococcus aureus [Group II: (10(2)), Group III: (10(3)), Group IV: (10(6))] were squirted on the decorticated lamina site. All animals were sacrificed after 2 weeks, and then blood cultures and cultures from fascia, muscle and bone were obtained. Bacterial number in each tissue was measured as colony-forming unit per gram tissue. Titanium microscrews were placed in 0.5 ml tryptic soy broth and vortexed than plated on trypticase soy agar to determine bacterial growth. Two animals from each group were subjected to histological examination.
Blood cultures obtained by intra-atrial puncture after 2 weeks were negative in all groups indicating no systemical infection developed. Bacterial cultures were negative in all specimens of Group I (control group). A significant osseous infection was confirmed in Groups II, III and IV. Comparison of bacterial counts in bone cultures showed no significant difference between Group III (10(3) CFU/10 microl) and Group IV (10(6) CFU/10 microl) (P > 0.05), while both groups had significantly higher counts than Group II (10(2) CFU/10 microl) (P > 0.05). Microscopic findings of supurrative inflammation were present only in Group IV (10(6) CFU/10 microl).
This study shows that inoculation of S. aureus in 10(6) CFU/10 microl concentration at the decorticated lamina after implantation of a titanium screw in rat spine is a reproducible model for spinal infection and can be used for the animal model of prophylaxis and treatment and of postoperative infection.
脊柱手术的术后感染率约为1%。然而，当使用金属植入物时，术后感染率显著增加，据报道在2.1%至8.5%之间。本研究旨在建立一种使用金属植入物的大鼠脊柱感染模型。
40只雄性白色斯普拉格-道利大鼠随机分为四组。对所有大鼠在手术显微镜下，于椎板去皮质后在胸腰段区域（T10-L1）植入一枚3毫米钛微螺钉。在第一组（对照组）中，向去皮质的椎板部位喷洒无菌等渗溶液，在其他三组中，分别喷洒不同浓度的金黄色葡萄球菌[第二组：（10²），第三组：（10³），第四组：（10⁶）]。2周后处死所有动物，然后进行血培养，并获取筋膜、肌肉和骨的培养物。测量每个组织中的细菌数量，以每克组织的菌落形成单位表示。将钛微螺钉置于0.5毫升胰蛋白胨大豆肉汤中涡旋振荡，然后接种于胰蛋白胨大豆琼脂平板上以确定细菌生长情况。每组选取两只动物进行组织学检查。
2周后通过心房穿刺获得的血培养在所有组中均为阴性，表明未发生全身性感染。第一组（对照组）所有标本的细菌培养均为阴性。在第二组、第三组和第四组中证实存在明显的骨感染。骨培养物中细菌计数的比较显示，第三组（10³CFU/10微升）和第四组（10⁶CFU/10微升）之间无显著差异（P>0.05），而这两组的计数均显著高于第二组（10²CFU/10微升）（P>0.05）。仅在第四组（10⁶CFU/10微升）中观察到化脓性炎症的显微镜下表现。
本研究表明，在大鼠脊柱植入钛螺钉后，于去皮质的椎板部位接种浓度为10⁶CFU/10微升的金黄色葡萄球菌是一种可重复的脊柱感染模型，可用于预防、治疗及术后感染的动物模型研究。
