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Bacterial identification in herniated intervertebral discs: a prospective cohort study
Nelson Astur1, Delio Eulalio Martins1, Michel Kanas1
1Department of Orthopaedics and Traumatology, Hospital Israelita Albert Einstein, São Paulo, Brazil.
Background Context:
Reports of Cutibacterium acnes isolated in cultures of intervertebral disc samples suggest it as possibly responsible for inflammatory conditions causing Modic changes on spinal magnetic resonance imaging (MRI).
Purpose:
Our objective was to investigate the prevalence of C. acnes in samples of intervertebral disc of patients with lumbar disc herniation; to investigate prognostic factors and the relationship of Modic changes with infection 1 year after microdiscectomy.
Study Design:
Prospective cohort study.
Patient Sample:
In this single-center study, patients consecutively operated on for disc herniation had samples of the disc, multifidus muscle and ligamentum flavum (as an indication of contamination) extracted for culture.
Outcome Measures:
Age, sex, alcohol and tobacco consumption, body mass index; function, pain, and Modic chances in MRI before surgery and MRI 1 year later; rate of disc, muscle and ligament infection (primary outcome); diabetes and corticoid use (confoundings).
Methods:
The protruded disc, muscle and ligament samples were sent for culture analysis in up to 30 minutes. A subsample of 17 patients underwent next-generation sequencing (NGS) molecular analysis too. We performed descriptive analysis and comparison of groups of patients with and without infection or contamination using Student's t, Mann-Whitney, chi-square, or Fisher's exact tests as appropriate, and pre- and postsurgical comparisons with the Wilcoxon test.
Results:
From January 2018 to September 2019, 112 patients underwent open lumbar microdiscectomy, 67 (59.8%) men. Cultures showed 7 (6.3%) positive cases in the disc (2 with C. acnes), 3 (2.7%) in the ligament, and 12 (10, 7%) in muscle. No evidence of a difference in Modic alterations pre- or postoperatively was found between patients with and without positive culture 1 year after surgery. No association was found between culture positivity and functional or pain differences either. NGS results were all negative for C. acnes.
Conclusions:
We identified infective bacterial presence in the herniated disc in less than 2% of patients with disc herniation. C. acnes was not identified in any disc microbiome analysis. No significant association was observed between positivity for tissue infection and any clinical prognostic factor.
Insights
Cutibacterium acnes (C. acnes) infection is not a significant factor in lumbar disc herniation or Modic changes post-microdiscectomy. Bacterial presence in discs was low, with no link to clinical outcomes.
Area of Science:
- Spinal surgery
- Infectious disease
- Radiology
Background:
- Cutibacterium acnes (C. acnes) presence in intervertebral disc cultures suggests a role in inflammatory conditions causing Modic changes on MRI.
- Investigating C. acnes prevalence is crucial for understanding its potential impact on spinal health.
Purpose of the Study:
- To determine the prevalence of C. acnes in lumbar disc herniation samples.
- To identify prognostic factors and the relationship between Modic changes and infection one year post-microdiscectomy.
Main Methods:
- Prospective cohort study involving 112 patients undergoing lumbar microdiscectomy.
- Disc, muscle, and ligament samples were cultured; a subset underwent next-generation sequencing (NGS).
- Clinical outcomes, Modic changes, and potential confounding factors were assessed pre- and post-surgery.
Main Results:
- Cultures revealed low bacterial presence in discs (6.3%) and ligaments (2.7%), with C. acnes found in 2 disc samples.
- No significant differences in Modic alterations or clinical outcomes (pain, function) were observed between infected and non-infected patients one year post-surgery.
- NGS analysis did not detect C. acnes in any samples.
Conclusions:
- Infective bacterial presence in herniated discs is uncommon (<2%), and C. acnes was not detected via disc microbiome analysis.
- No significant association was found between positive tissue infection and clinical prognostic factors after microdiscectomy.
- The study suggests C. acnes is unlikely to be a primary driver of Modic changes or poor outcomes in this patient group.
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