The clinical characteristics and outcomes of anaerobic spondylodiscitis: a retrospective observational study

Background : Pyogenic spondylodiscitis is rarely caused by anaerobic organisms. This retrospective study evaluated the clinical manifestations and treatment outcomes in patients affected by anaerobic spondylodiscitis. Methods : We performed a retrospective analysis of medical records from individuals diagnosed with anaerobic spondylodiscitis between January 2018 and January 2024. Results : From January 2018 to January 2024, 373 cases of pyogenic spondylodiscitis were identified in our department. Twenty-three patients (6.2%; 16 males and 7 females), with a mean age of 63.7 years (63.7±14.3 years), were diagnosed with anaerobic spondylodiscitis during this period. All patients presented with persistent back pain lasting over one month, 5 patients (21.7%) had fever, and 3 patients (13.0%) had sciatica. The lumbar spine affected 18 patients (78.3%), and the thoracic spine affected 5 (21.7%) patients. Computed tomography images usually reveal erosion and destruction of adjacent endplates and vertebral bodies. T1-weighted Magnetic resonance imaging revealed a reduction in the signal intensity of the vertebral body, endplate and intervertebral disc. T2-weighted images demonstrate increased signal intensity of the vertebral body and/or disc. The most common gram-positive coccus is Parvimonas micra , and the gram-negative bacilli is Bacteroid fragilis . There was no statistically significant variation in the cure rate between the conservative treatment group and the surgical treatment group (P>0.05). Conclusions : The incidence of anaerobic spondylodiscitis might be underestimated, as it is difficult to recover anaerobic bacteria. Next-generation sequencing demonstrated superior diagnostic accuracy for anaerobic pathogen identification compared to traditional culture methods. A total of 12 weeks of antibiotic therapy is recommended, and a duration of less than 6 weeks may result in recurrence.