Histological Identification of Propionibacterium acnes in Nonpyogenic Degenerated Intervertebral Discs

Figure 2

Histological evidence of P. acnes in nonpyogenic degenerated intervertebral disc. (a) HE staining revealed rod-shaped bacteria growing in cluster (marked with black arrows); (b) modified Brown-Brenn staining further revealed the bacteria as blue, indicating that they were Gram-positive (marked with black arrows). The intervertebral disc was harvested from the patient described in Figure 1, who was identified as P. acnes-positive using 16S r DNA PCR at the level of L4~L5 (patient’s ID: number 9). (c)-(d) By contrast, no bacterium was found in either HE or modified Brown-Brenn staining in a P. acnes-negative intervertebral disc.