No evidence for presence of bacteria in modic type I changes

Recent studies suggest an association between sciatica and Propionibacterium acnes. "Modic type I changes" in the vertebrae are closely associated with sciatica and lower back pain, and recent studies have questioned the ability of conventional magnetic resonance imaging (MRI) to differentiate between degenerative Modic type I changes and vertebral abnormalities caused by infection.

To test whether bacteria could be cultured from biopsies of Modic type I changes.

Twenty-four consecutive patients with Modic type I changes in lumbar vertebrae had a biopsy taken from the affected vertebra by a strict aseptic procedure. The biopsy was split into two specimens, which were inoculated into thioglycolate agar tubes in the surgical theatre and transported to the microbiology laboratory. In the laboratory, one specimen was streaked onto plates and analyzed for anaerobic and aerobic culture. The other tube was left unopened and incubated directly. Plates and tubes were incubated for 2 weeks and observed for visible growth.

None of the biopsies yielded growth of anaerobic bacteria. In one patient, both biopsies yielded growth of Staphylococcus epidermidis, and in another patient coagulase-negative staphylococci were isolated from one biopsy. Both patients received oral antibiotics without convincing effect on symptoms.

Our results showed no evidence of bacteria in vertebrae with Modic type I changes. The isolation of staphylococci from two patients probably represented contamination.