Monday, January 9, 2017

Herniated lumbar discs are often culture positive for Propionibacterium

Modic changes in the adjacent vertebrae due to disc material infection with Propionibacterium acnes in patients with lumbar disc herniation

Modic changes (MC) are pathological changes in the vertebrae. These changes are situated in both the body of the vertebrae and in the end plate of the neighboring disc. These authors sought to  evaluate the MCs seen on MRI in patients with disc herniation and positive for P. acnes.

They enrolled a total of 120 patients (69 male and 51 female with mean age of 43.15 ± 12.62 ) with disc herniation surgery, culturing the tissue excised during discectomy in both anaerobic and aerobic media. Cultured P. acnes were detected by 16S rRNA-based polymerase chain reaction (PCR). MCs of baseline MRI were evaluated.

60 disc samples and 8 muscle samples were positive for microorganisms. 36 of 46 patients with P. acnes in their sample had MCs.

They concluded that P. acnes can lead to edema on the vertebrae endplates near to infected area.

Comment: In this study the association of Propionibacterium culture positive disc material and modic changes is striking (see Table below). This is important because it demonstrates a correlation between two distinct objectively determined findings.

For those of us in the shoulder world, this is additionally interesting because the Propionibacterium appear to have colonized the disc material without being iatrogenically introduced. We must wonder if the seeding of the disc material was hematogenous or if it resulted from bacteria moving from the dermis to the deeper tissues.