Objective:To compare the microbiology, clinical characteristics and therapeutic efficacy of native suppurative spondylitis (NVO) and postoperative suppurative spondylitis (PVO), and analyze the factors affecting the prognosis.Methods:All patients with suppurative spondylitis were retrospectively analyzed from December 2010 to December 2019. A total of 46 patients were enrolled in this study. They were divided into two groups. There were 30 cases in NVO group, 18 males and 12 females; The age was 50.47±20.45 years, aged 15-73 years. There were 16 cases in PVO group, 10 males and 6 females; The age was 52.13±18.80 years, aged 14-73 years. In group NVO, 23 cases (76.7%) were in lumbar vertebrae, 5 cases (16.7%) in thoracic vertebrae and 2 cases (6.7%) in cervical vertebrae; in group PVO, 11 cases (68.8%) in lumbar vertebrae and 5 cases (31.2%) in thoracic vertebrae. Twenty-eight patients had neurological dysfunction before surgery. There were 25 cases of grade D (16 cases in group NVO and 9 cases in group PVO) and 3 cases of grade C (1 case in group NVO and 2 cases in group PVO), following the instructions of American Spinal Injury Association (ASIA) neurological function classification. All patients were given bed rest, nutritional support and antibiotic therapy; surgical treatment for patients with poor outcomes or aggravated symptoms. The patients were followed up after operation, the observation indexes included leukocyte count, erythrocyte sedimentation rate and C -reactive protein to evaluate the postoperative curative effect. The internal fixation device was evaluated for looseness and fracture by imaging examination. At the same time, the changes of visual analogue scale, ASIA neurological function grade were recorded to evaluate the clinical efficacy.Results:Two patients in NVO group were treated with antibiotics, and all the other patients successfully completed the operation. The diseased tissues were sent for pathological examination during the operation. The results showed that they were diagnosed as suppurative spondylitis. All patients were followed up for 12-24 months. Both groups were treated with intravenous and oral antibiotics, and the time of antibiotic treatment in group PVO was longer than that in group NVO without significant difference ( t=1.74, P=0.088). The leukocyte, C-reactive protein, erythrocyte sedimentation rate, visual analogue scale (VAS), were significantly improved in both groups at different time points after operation ( P<0.05) . There was no significant difference in leukocyte, C -reactive protein, erythrocyte sedimentation rate or VAS score between the two groups at the same time point after operation ( P>0.05). The neurological function of patients after operation was significantly improved compared with that before operation. In group NVO, 16 cases recovered from ASIA grade D to grade E, 1 case from grade C to grade D; 9 cases in group PVO recovered from grade D to grade E and 2 cases recovered from grade C to grade D. Till the last follow-up, 3 patients in group NVO recurred, the recurrence rate was 10% (3/30); 7 patients in group PVO recurred, the recurrence rate was 43.8%; the recurrence rate of group PVO was higher than that of group NVO, the difference was statistically significant (χ 2=5.14, P=0.023). Among 39 patients with spinal internal fixation, 12.8% (1 NVO, 4 PVO) had recurrent infection after internal fixation. Therefore, re-operation was performed to remove the internal fixator for infection control, patients recovered after conservative treatment such as immobilization and systemic anti-infection By univariate analysis, multiple vertebral involvement and abscess formation ( OR=11.00, P=0.006; OR=9.00, P=0.047) were significantly associated with pyogenic spondylitis recurrence; there was a tendency for pyogenic spondylitis recurrence among microbial infection ( OR=1.87, P=0.416), spinal prosthesis ( OR=7.20, P=0.074) and allogenic bone ( OR=1.78, P=0.478), yet not obvious. Multivariate analysis indicated that multiple vertebral involvement ( OR=10.49, P=0.038) was a risk factor for pyogenic spondylitis recurrence. Conclusion:The treatment of PVO is more challenging than NVO, especially in the cases of spinal implant infection. Although the antibiotic treatment time of PVO is longer than that of NVO, the recurrence rate of PVO is higher. Longer antibiotic therapy and, if necessary, surgical debridement or removal of implants are important approaches to successful treatment of PVO.