Bacterial identification in herniated intervertebral discs: a prospective cohort study

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.