LAUSR

Background Low back pain (LBP) is strongly associated with Modic changes. The hypothesis of local infectious origin was raised, especially with Proprionibacterium acnes (PA).The possibility of contamination with saprophyte germs coming from the skin during surgery by posterior approach or by epidural infiltration preceding the surgery was also discussed, but not proved. Objectives The main objective of this study was to evaluate the prevalence of slow growing bacterias (SGB) in the intervertebral disc (IVD) obtained during a lumbar spine surgery by anterior approach in Modic 1 and 2 changes. A secondary objective was to compare the prevalence of SGB in IVD in lumbar spine surgery obtained by anterior approach to that obtained by posterior approach in herniated disc. Methods 45 patients with chronic LBP or sciatica were included in the study, representing 48 IVD. When patients underwent lumbar spine surgery by an anterior approach, 2 samples of the disc were collected for bacteriological analysis: one sample from the anterior part of the disc distant from epidural space and one sample from the posterior part of the disc. 77 discs samples were obtained, 32 discs samples in Modic 1 or 2 changes by anterior approach, 26 discs samples in no Modic IVD by anterior approach, 19 disc samples obtained by posterior approach. The method to collect disc material was strictly aseptic. Samples were analysed by conventional microbial cultures with specialised enrichmen, molecular detection by universal rRNA gene PCR plus sequencing assay. Additionally, all clinical specimens were specifically tested for PA detection using a highly sensitive specific PCR Results Regarding bacterial cultures, 12 out 77 disc samples were positive (16%), including 10 (13%) for PA. The PA specific PCR was positive for one (1%) specimen obtained by posterior approach. The 16s RNA detection was positive for 6 specimen (8%), including one for PA (1%).Modic 1–2: Cultures were positive in 5 cases (16%) with 3 for PA (10%). No specific PA PCR was positive. Only one sample was positive for PA in both culture and 16s PCR. Comparison between anterior and posterior approach: Among the PA positive cultures, 5 were identified from anterior specimens (8.62%) and 5 from posterior specimens (26.32%). Regarding PA cultures,the posterior fragments were more frequently positive than the anterior fragments (p=0.046). The number of epidural infiltrations of the lumbar spine does not seem to influence the bacterial contamination prevalence p=0.746. The time between the epidural infiltration of the lumbar spine and the surgery does not seem to influence the bacterial contamination prevalence (more or less 6 month) p=0.23. Conclusions SGB has been identified in culture in 16% of the samples obtained in Modic 1 and 2 changes. The prevalence of PA in culture was significantly higher in samples of IVD collected by a posterior approach compared to anterior approach in spine surgery suggesting a contamination. The results of the specific PCR PAs with a single weakly positive sample reinforce the hypothesis of contamination. Disclosure of Interest None declared