106. Subclinical propionibacterium acnes infection estimation in the intervertebral disc (SPInE-ID)

Abstract

BACKGROUND CONTEXT Low back pain and vertebral end plate abnormalities are common conditions within the population. Subclinical infection caused by indolent pathogens can potentially lead to these findings, with differentiation between them notably challenging from a clinical perspective. Progressive infection of the intervertebral disc has been extensively associated with increasing low back pain, with Propionibacterium acnes specifically implicated with in relation to sciatica. PURPOSE To identify if the presence of an infective pathogen within the intervertebral disc is primary or is a result of intraoperative contamination, and whether this correlates to low back pain. STUDY DESIGN/SETTING Single-center prospective cohort. PATIENT SAMPLE Subjects included within the study will be between the ages of 18 and 65 years and have a diagnosis of lumbar disc herniation requiring open decompression surgery. OUTCOME MEASURES Tissue culture and pathogen identificationNRSODIEQ-5DModic changesESR, CRP, Leucogram. METHODS Excised herniated disc fragments, muscle and ligamentum flavum samples will be collected during surgery and sent to microbiology for tissue culture and pathogen identification. A disc infection is considered if only disc tissue has a positive culture growth. Score questionnaires for pain, functionality and quality of life will be given preoperatively and at 1, 3, 6 and 12 months postoperatively. An MRI will be performed 12 months after surgery for analysis of Modic changes and baseline comparison. The primary endpoint is the rate of disc infection in patients with symptomatic degenerative disease. The secondary endpoints will be performance scores, Modic incidence and size. RESULTS Ninety-five patients were enrolled and completed one-year follow-up with full data collected. Eighteen patients (18.9%) presented at least one of the 3 collected tissues with a positive culture and 4 patients (4.21%) presented only intervertebral disc positive tissue culture, which was considered disc infection, while other patients were considered contaminated. P. acnes was cultured in 2 of the 4 infected discs. NRS for low back pain and sciatica, and ODI improved from mean baseline 7, 6 and 45 to final follow-up 1.2, 2.2, and 16, respectively. Performance score improvements were not statistically related to presence of disc infection. Modic changes and increasing of size over time were not related to disc positive culture. No patients developed clinical discitis over time. CONCLUSIONS Based on a strict methodology of tissue culturing and contamination controls, subclinical infection rate of the intervertebral lumbar disc is at 4.2% and is overestimated in the current literature. Subclinical disc infection is not related to worse outcomes after lumbar microdiscectomy in patients with lumbar disc herniation, and worsening of Modic changes over time is not related to the presence of pathogens in the disc. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.