A comparative study of pyogenic and tuberculous spondylodiscitis

Study Design. We performed a retrospective review of 126 cases of infectious spondylodiscitis over a 4-year period. Objective. Differentiation between pyogenic spondylodiscitis (PS) and tuberculous spondylodiscitis (TS) is essential for deciding on the appropriate therapeutic regimen. The aim of this study was to compare the characteristics of the 2 forms of spondylodiscitis. Summary of Backgrounf Data. There has been much effort to distinguish the radiologic findings in PS versus TS, but classification based on radiologic findings alone had limitations yet. Methods. We compared the predisposing factors or associated illnesses, clinical, radiologic, and laboratory features of microbiologically confirmed cases of PS and TS in 2 university hospitals. Results. Of 126 patients, 79 had PS and 47 TS. PS was more frequently associated with the followings: previous invasive spinal procedures (PS vs. TS: 32.9% vs. 8.5%), preceding bacteremia (13.9% vs. 0%), chronic renal failure (12.7% vs. 0%), liver cirrhosis (13.9% vs. 0%), fever (temperature >38°C) (48.1% vs. 17.0%), white blood cell counts over 10,000/mm³ (41.8% vs. 19.1%), fraction of neutrophils >75% (49.4% vs. 27.7%), C-reactive protein levels over 5 mg/dL (58.2% vs. 27.7%), erythrocyte sedimentation rate levels over 40 mm/h (84.4% vs. 66.0%), and ALP levels over 120 IU/L (45.6% vs. 17.0%). TS was frequently associated with active tuberculosis of other organs (0% vs. 31.9%), longer diagnostic delay (47.6 vs. 106.3 days), involvement of thoracic spines (21.5% vs. 38.3%), and involvement of ≥3 spinal levels (11.4% vs. 36.2%). Conclusion. Previous invasive spinal procedures, preceding bacteremia, fever, higher white blood cell counts, C-reactive protein, ALP, and higher fraction of neutrophils are suggestive of PS. Concurrent active tuberculosis, more indolent course and involvement of thoracic spines are suggestive of TS. When the causative organism is not identified despite all efforts at diagnosis, combination of the clinical, radiologic, and laboratory characteristics of the patient is helpful.