Anaerobic spondylodiscitis: a retrospective analysis

Abstract

Background: This retrospective study analyzed the clinical characteristics and outcomes of patients with anaerobic spondylodiscitis.

Methods: From a total of 382 patients with infectious spondylodiscitis, nine patients (2.4%; two male and seven female with an average age of 67 years) with anaerobic spondylodiscitis between March 2003 and March 2017 were analyzed.

Results: Most of the patients (77.8%) initially presented with afebrile back pain. Hematogenous spread occurred in seven patients and postoperative infection in two patients. Bacteroid fragilis was the most common pathogen isolated from three patients. Atypical radiographic characteristics, including a vertebral fracture with the preservation of disk height or coexisting spondylolytic spondylolisthesis, occurred in four patients with hematogenous anaerobic spondylodiscitis. The eradication rate of anaerobic infection was significantly higher in the patients with hematogenous infection than in those with postoperative infection (100% vs. 0%, p = 0.0476). Anaerobic spondylodiscitis accounted for 2.4% of cases of infectious spondylodiscitis and predominantly affected the female patients.

Conclusions: Diagnostic delay may occur because of atypical spinal radiographs if the patient reports only back pain but no fever. Anaerobic infection following elective spinal instrumentation has a higher recurrence rate.

Keywords: Anaerobic spondylodiscitis; Atypical radiographic characteristics.

Fig. 1

Anaerobic spondylodiscitis mimicking a fragile vertebral body compression fracture in a 72-year-old female (No. 3) with chronic lower back pain in the absence of fever. A Loss of vertebral body height without the widening of the interpedicular distance and interspinal process distance was observed at the L2 vertebra in the anteroposterior view of the lumbar spine radiograph. B Compression fracture of the L2 vertebra with preserved disk height was observed as an anterior wedging deformity and vertebral body height loss in the lateral and anteroposterior view of the lumbar spinal radiograph. C Heterogeneous enhancement of the L2 vertebral body and prevertebral space was observed on a sagittal gadolinium-enhanced fat-suppressed T1-weighted magnetic resonance image. D Enhancement of the paraspinal soft tissue muscle surrounding the L2 vertebral body. A spinal epidural abscess was observed as an epidural mass with central hypointensity and surrounding linear enhancement on an axial view of contrast-enhanced T1-weighted imaging

Fig. 2

71-year-old female (No.7) with anaerobic spondylodiscitis presenting with multiple vertebral body compression fractures. A Lumbar anteroposterior view displaying multiple vertebral body compression fractures. B Intervertebral cleft within an L2 vertebral body compression fracture in the lumbar lateral and anteroposterior view. C Sagittal gadolinium-enhanced fat-suppressed T1-weighted imaging of abscess formation within the L2 vertebral body, and osteomyelitis in the L4 and L5 vertebral bodies with purulent collection in the intervertebral space (D, E, F) Contrast-enhanced T1-weighted axial imaging of a circumferential spinal epidural abscess observed at L2–S1 levels and a right-side iliopsoas muscle abscess

Fig. 3

Anaerobic spondylodiscitis with concomitant spondylolytic spondylolisthesis in a 53-year-old male (No. 1). A1, 2 Grade 2 spondylolisthesis with pars interarticularis deficiency at L5–S1 observed on plain radiographs. B1 Infectious spondylodiscitis at L5–S1 with a destroyed disk on sagittal enhanced T1-weighted magnetic resonance imaging (MRI). The dorsal epidural abscesses are visible (white arrows). B2 Heterogeneous enhancement of the lumbosacral facet joint indicating that the facet joint was destroyed through infection (white arrow). Collection of purulent pus extended to the pars interarticularis deficiency (black arrow). C1, 2 Heterogenous enhancement of L5–S1, prevertebral space, bilateral foramina, and spinal canal. The collection of pus was acuminated in the lumbosacral facet joint space (white arrow). D1, 2 Anaerobic spondylodiscitis with concomitant spondylolytic spondylolisthesis diagnosed through contrast-enhanced MRI and bacterial cultures. The patient underwent anterior sequestration and reconstruction with interbody fusion with autogenous iliac crest and instrumentation. The solid bony fusion without the loosening of the instrumentation was observed at the 2-year follow-up