Histological Identification of<i>Propionibacterium acnes</i>in Nonpyogenic Degenerated Intervertebral Discs

Abstract

<i>Purpose</i>. Low-virulence anaerobic bacteria, especially the <i>Propionibacterium acnes (P. acnes)</i>, have been thought to be a new pathogeny for a series of disc diseases. However, until now, there has been no histological evidence to confirm this link. The purpose of this study was to confirm the presence of <i>P. acnes</i> in nonpyogenic intervertebral discs via histological observation. <i>Method</i>. Degenerated intervertebral discs were harvested from 76 patients with low back pain and/or sciatica but without any symptoms of discitis or spondylodiscitis. The samples were cultured under anaerobic conditions and then examined using 16S rDNA PCR to screen for <i>P. acnes</i>. Samples found to be positive for <i>P. acnes</i> were stained with hematoxylin-eosin (HE) and modified Brown-Brenn staining and observed under a microscope. <i>Results</i>. Here, 16 intervertebral discs were found to be positive for <i>P. acnes</i> via 16S rDNA PCR and the prevalence was 21.05% (16/76). Among them, 7 samples had visible microbes stained with HE and modified Brown-Brenn staining. Morphological examination showed the bacteria to be Gram-positive and rod-shaped, so they were considered <i>P. acnes</i>. <i>Conclusion</i>. <i>P. acnes</i> is capable of colonizing some degenerated intervertebral discs without causing discitis, and its presence could be further confirmed by histological evidence. Targeting these bacteria may be a promising therapy method for some disc diseases.