Criteria and implant treatment for pyogenic spinal infection in dogs / 中国组织工程研究

ABSTRACT

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:Total y 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, al 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 surgical y at various postoperative time points (4, 8, 12, 24 weeks) when the dogs were kil ed. 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 uneventful y. 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). Al 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.