Intradiscal Cutibacterium acnes Prevalence Immediately Prior to Fusion or Total Disc Replacement Device Implantation: A Prospective Registry Study of Cervical and Lumbar Discs.

BACKGROUND: Cutibacterium acnes has been identified in excised intervertebral disc tissue in multiple studies; however, contamination remains a persistent limitation, and all prior investigations have relied on excised tissue sampling. No study has evaluated swab-based sampling directly from the disc space. The primary aim of this study was to determine the prevalence of C acnes in intervertebral disc spaces following discectomy but prior to fusion cage or total disc replacement implantation using anaerobic culture and quantitative polymerase chain reaction (qPCR) and to assess concordance between detection methods. METHODS: This prospective cohort registry study included 29 patients (53 discs: 28 cervical, 25 lumbar) undergoing discectomy. Prior to discectomy, deep tissue was irrigated with 0.05% chlorhexidine gluconate (Irrisept) to suppress dermal-origin organisms. Following discectomy and before device implantation, a sterile swab was inserted into the disc space. Swabs were divided for 21-day anaerobic culture with semiquantitative grading and 16S rRNA qPCR (positivity threshold >1.04 copies/reaction). Cohen kappa, McNemar test, and Clopper-Pearson exact 95% confidence intervals were calculated. RESULTS: Overall disc-level prevalence was 43.4% (23/53; 95% CI: 29.8%-57.7%) by culture and 54.7% (29/53; 95% CI: 40.4%-68.4%) by qPCR. Cervical discs demonstrated significantly higher culture positivity than lumbar discs (71.4% vs 12.0%; P < 0.001), while qPCR positivity was similar (50.0% vs 60.0%). When either method was positive, prevalence was 85.7% in cervical and 64.0% in lumbar discs. Inter-method agreement was poor overall (κ = -0.044; 95% CI: -0.31 to 0.22). In lumbar discs, qPCR identified significantly more positive discs than culture (P = 0.003). CONCLUSIONS: Cutibacterium acnes is detectable in intervertebral disc spaces at high rates using swab-based sampling after deep-tissue chlorhexidine gluconate irrigation, particularly in cervical discs. Poor concordance between culture and qPCR suggests each method identifies distinct subsets of positive discs, particularly in lumbar discs. CLINICAL RELEVANCE: This is the first report of disc-space swab analysis for intradiscal C acnes detection at the time of cervical and lumbar surgery. Detection prior to fusion cage or total disc replacement implantation may help characterize the microbiological environment at the implant interface and supports further investigation into strategies to reduce disc-space C acnes burden prior to implantation, particularly in total disc replacement.