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Prevalence of Propionibacterium acnes in Intervertebral Discs of Patients Undergoing Lumbar Microdiscectomy: A
Manu N Capoor1,2, Filip Ruzicka3, Tana Machackova2
1Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, NY, United States of America.
Background:
The relationship between intervertebral disc degeneration and chronic infection by Propionibacterium acnes is controversial with contradictory evidence available in the literature. Previous studies investigating these relationships were under-powered and fraught with methodical differences; moreover, they have not taken into consideration P. acnes' ability to form biofilms or attempted to quantitate the bioburden with regard to determining bacterial counts/genome equivalents as criteria to differentiate true infection from contamination. The aim of this prospective cross-sectional study was to determine the prevalence of P. acnes in patients undergoing lumbar disc microdiscectomy.
Methods And Findings:
The sample consisted of 290 adult patients undergoing lumbar microdiscectomy for symptomatic lumbar disc herniation. An intraoperative biopsy and pre-operative clinical data were taken in all cases. One biopsy fragment was homogenized and used for quantitative anaerobic culture and a second was frozen and used for real-time PCR-based quantification of P. acnes genomes. P. acnes was identified in 115 cases (40%), coagulase-negative staphylococci in 31 cases (11%) and alpha-hemolytic streptococci in 8 cases (3%). P. acnes counts ranged from 100 to 9000 CFU/ml with a median of 400 CFU/ml. The prevalence of intervertebral discs with abundant P. acnes (≥ 1x103 CFU/ml) was 11% (39 cases). There was significant correlation between the bacterial counts obtained by culture and the number of P. acnes genomes detected by real-time PCR (r = 0.4363, p<0.0001).
Conclusions:
In a large series of patients, the prevalence of discs with abundant P. acnes was 11%. We believe, disc tissue homogenization releases P. acnes from the biofilm so that they can then potentially be cultured, reducing the rate of false-negative cultures. Further, quantification study revealing significant bioburden based on both culture and real-time PCR minimize the likelihood that observed findings are due to contamination and supports the hypothesis P. acnes acts as a pathogen in these cases of degenerative disc disease.
Insights
Propionibacterium acnes was found in 40% of patients undergoing lumbar microdiscectomy. Abundant P. acnes (≥ 1x103 CFU/ml) was present in 11% of discs, supporting its role in degenerative disc disease.
Area of Science:
- Microbiology
- Orthopedic Surgery
- Infectious Disease
Background:
- The role of Propionibacterium acnes (P. acnes) in intervertebral disc degeneration is debated due to conflicting evidence.
- Previous studies lacked power and standardized methods, failing to account for P. acnes biofilms or quantify bacterial load.
Purpose of the Study:
- To determine the prevalence of P. acnes in patients undergoing lumbar disc microdiscectomy.
- To quantify P. acnes bioburden to differentiate infection from contamination.
Main Methods:
- Prospective cross-sectional study of 290 adult patients undergoing lumbar microdiscectomy.
- Intraoperative disc biopsy for quantitative anaerobic culture and real-time PCR for P. acnes genome quantification.
- Analysis of pre-operative clinical data.
Main Results:
- P. acnes was identified in 40% of biopsies (115/290).
- Coagulase-negative staphylococci and alpha-hemolytic streptococci were found in 11% and 3% of cases, respectively.
- Abundant P. acnes (≥ 1x103 CFU/ml) was present in 11% of discs (39/290), with significant correlation between culture and PCR results (r = 0.4363, p<0.0001).
Conclusions:
- A significant prevalence (11%) of abundant P. acnes was found in degenerated discs.
- Disc tissue homogenization and quantification methods reduce false negatives and support P. acnes as a pathogen in degenerative disc disease.
