149. Results of the Degenerate-Disc Infection Study with Contaminant Control (DISC) study

BACKGROUND CONTEXT A bacterial cause of disc degeneration has evoked several controversies and if true may lead to a major shift in treatment paradigm. Earlier studies analyzing the relationship of bacterial disc infection within a degenerative cohort featured prolonged cultures, susceptible to contamination. Although more recent studies have demonstrated an associated biofilm activity amongst other factors toward an infectious etiology to pain, the question remains unanswered. The DISC trial aims to investigate this theory further in examining infection rates using a traumatic control cohort in comparison to a degenerative internal control cohort, and a sham surgery cohort (sampling only sterile paraspinal tissue). The current study is the largest in the literature evaluating the growth of organisms (or possible contamination rate) in paraspinal tissue if prolonged cultures are performed. Protocols on methodology have been previously published. PURPOSE (1) To investigate the infection rates across cohorts (degenerative vs traumatic control; paraspinal/disc controls vs combined sampling cohorts) using stringent standardized aseptic surgical technique and laboratory processing. (2) To compare our findings to that of the literature and make a statement in support of or against a possible contamination theory to positive cultures. STUDY DESIGN/SETTING Multicenter, multisurgeon case-control trial. PATIENT SAMPLE A total of 815 surgical samples were retrieved across a 3-year period (2013-2015) including 25 trauma controls (nondegenerative), 193 disc-only samples (internal control), 551 “disc and paraspinal" samples, and 46 paraspinal-only controls (sham surgery group). OUTCOME MEASURES (1) Growth/contamination rate (%) per cohort. (2) Chi square of growth in disc vs paraspinal samples as a means of examining the distribution of false positive and contaminant growth. (3) The impact of previous injections/surgery on positive disc or paraspinal growth. (4) Correlation of Modic changes with positive growth rates (Kruskal Wallis Test). (5) Analyses of the distribution of species in positive samples. METHODS The DISC trial is registered under ANZ clinical trials registry - ACTRN12616000541404. Institutional ethics review was obtained (HREC Northern Sector 13/218) at the primary center and further centers (n=6) were recruited, with permission granted for multiple surgical investigators approved individually as part of the DISC Study Collaboration. Patients undergoing microdiscectomy and decompression were eligible for trial entry with tissue specimens obtained using strict aseptic technique for histopathological examination. All specimens were handled with sterile instruments only and by a fresh instrument to a sterile pot that was closed immediately. Separate pots were used for the disc and paraspinal ligament tissue respectively with similar stringent processing during microbiological and histopathological assessment RESULTS There was an expected significant difference in gender and age associated with the traumatic control group compared to other cohorts. There was a higher percentage of positive growth in the traumatic control group in comparison to the disc and paraspinal and disc only groups across positive disc growth (48% vs 27% vs 17%, p CONCLUSIONS There was more positive true disc culture (negative paraspinal) than in the degenerate population. If the assumption of aseptic technique during collection is maintained, these data are highly suggestive toward a contamination theory bias in the setting of discogenic back pain despite strict aseptic technique employed in multiple facilities across large Australian hospitals. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.