Objectives-To describe a large series of patients with vertebral osteomyelitis (VO), and to compare the clinical, biological, radiological, and prognostic features of pyogenic (PVO), tuberculous (TVO), and brucellar vertebral osteomyelitis (BVO). Methods-A retrospective multicentre study, which included 219 adult patients with VO with confirmed aetiology, who were diagnosed between 1983 and 1995 in two tertiary care centres. Of these patients, 105 (48%) had BVO, 72 (33%) PVO, and 42 (19%) TVO. Results-One hundred and forty eight (67.6%) patients were male and 71 (32.4%) female. The mean (SD) age was 50.4 (16.4) years (range 14-84) and the mean (SD) duration of symptoms before the diagnosis was 14 (16.8) weeks. In 127 patients (57.9%) the vertebral level involved was lumbar, in 70 (31.9%) thoracic, and in 16 (7.3%) cervical. One hundred and nineteen patients (54.4%) received only medical treatment and 100 (45.6%) required both medical and surgical treatment. The presence of diabetes mellitus, intravenous drug abuse, underlying chronic debilitating diseases or immunosuppression, previous infections, preceeding bacteraemia, recent vertebral surgery, leucocytosis, neutrophilia, and increased erythrocyte sedimentation rate (ESR) were significantly associated to PVO. A prolonged clinical course, thoracic segment involvement, absence of fever, presence of spinal deformity, neurological deficit, and paravertebral or epidural masses, were significantly more frequent in the group of TVO. The need for surgical treatment and the presence of severe functional sequelae were more frequent in the groups of PVO and TVO. Conclusion-There are significant clinical, biological, radiological, and prognostic diVerences between BVO, PVO, and TVO. These diVerences can point to the causal agent and orient the initial empirical medical treatment while awaiting a final microbiological diagnosis. (Ann Rheum Dis 1997;56:709-715) In 1975 Ross and Fleming rightly pointed out "neither common enough to be readily recognizable, nor rare enough to be a medical curiosity, vertebral osteomyelitis (VO) represents a diagnostic challenge to the physician". 1The clinical picture of VO is rather nonspecific. It commonly starts insidiously and follows an indolent course making early diagnosis diYcult.2-4 Consequently, patients often develop highly destructive lesions or neurological complications related to compression of the spinal cord or its roots.

We studied 31 cases of postoperative pyogenic spondylodiskitis (POS), comparing them with 72 cases of nonpostoperative pyogenic spondylodiskitis (NPOS). POS represents 30.1% of cases of pyogenic spondylodiskitis. The onset of symptoms occurred an average (+/-SD) of 27.7 (+/- 25.3) days following surgery. Predisposing factors were less frequent in POS than NPOS cases (P = .002). Neurological complications and inflammatory signs in the spine were more frequent with POS than with NPOS (P = .002 and P < .00001). Coagulase-negative Staphylococcus and anaerobic bacteria were more frequent in POS than in NPOS (P = .0001 and P = .05). Percutaneous bone biopsies yielded the etiology in 66.7% of cases, open bone biopsies in 100%, blood cultures in 55.6%, and cultures of adjacent foci in 94.4%. Eleven patients (35.5%) were cured with antimicrobial treatment, but surgical treatment was necessary in 64.5%. No relapses or deaths were recorded. Seventeen patients (54.8%) had severe functional sequelae, which were associated with inflammatory signs in the spine (P = .033), higher levels of leukocytosis (P = .05), higher erythrocyte sedimentation rates (P = .05), and paravertebral abscesses (P = .04).