Low Virulence Bacterial Infections of Intervertebral Discs and the Resultant Spinal Disease Processes

Purpose: The goal of this pilot project was to determine if there is a significant presence of low virulent bacterial infection in the involved intervertebral discs of several heretofore 'idiopathic' spinal disease processes. Previous historical literature focusing on the etiology of spinal disc herniations, discogenic pain, Scheuermann's Kyphosis and idiopathic scoliosis have not explored this concept, especially with the new, more thorough laboratory culture techniques now available. Low virulent bacterial pathogens have recently been found to be factors previously unappreciated in other areas of human disease. Stirling et al (Lancet 2001, 357:2024-5) have found a significant positive culture rate (19 of 36: 53%), especially of Propionibacterium acnes (16 of 19; 84%) in surgical lumbar disc herniation specimens.

Methods: This prospective study, (with IRB approval/consent) included patients (no age or ethnic exclusions), with no previous surgery in the same spinal area, no coexistent infections or immunologically compromised conditions, and appropriate clinical and radiographic criteria present to indicate surgery. Five diagnostic categories were utilized:I. Cervical spine intervertebral disc herniations (anterior approach, 30 discs)II. Lumbar spine intervertebral disc herniations (posterior approach, 30 discs)III. Lumbar spine discogenic pain (anterior approach, 30 discs)IV. Scheuermann's Kyphosis/idiopathic scoliosis (anterior approach, 30 discs)V. Trauma/neuromuscular deformity: "control" (anterior approach, 45 discs)All specimens were obtained sterilely immediately at the time of surgical excision and cultured using extended duration incubation techniques (repeated subcultures up to several weeks duration). Each was also reviewed microscopically. This study in no way changed the patients' surgical procedures or treatment course.

Results: A total of fourteen different bacterial entities were cultured, all potentially normal skin flora. "No growth" rates for each group were: I. Cervical: 41%, II. Lumbar: 29%, III. Discogenic 56%, IV. Deformity: 70%, and V. Control: 73%. When only "positive culture" rates per group of 15% or greater were noted, the following resulted: I. Cervical: 37% P. acnes; II. Lumbar: 36% Staphylococcus species and 18% P. acnes; III. Discogenic: 26% P. acnes; IV. Deformity: 15% P. acnes; and V. control: none.Group IV, idiopathic deformity cases, consisted of five scolioses and one kyphosis. The pain-free scolioses (age 13-15 yrs.) had two cases with all negative cultures, one with a single Staph species positive and one with single P. acnes positive (4 - 6 discs per case). The single Scheuermann's Kyphosis case (age 18 yrs.) had extreme, long standing spinal deformity pain complaints. Eight discs were harvested and four were positive for P. acnes. Interestingly, of the three neuromuscular scolioses in group V (control), with seven discs being harvested from each; one case had two discs Staph species positive, one had a single Peptostreptococcus disc, and the third had no growth in a disc. When all disc results were pooled, there was a 44% culture positive rate, P. acnes, being the most prominent at 19% and Staph species at 14%. No evidence for acute or chronic inflammatory change was noted on any stained microscopic evaluation, nor were any organisms actually visualized.

Conclusions: Low virulent bacterial infections, most notably P. acnes and Staph species, may play a significant role in the pathologic etiology of a number of human spinal conditions that eventually require surgical intervention, including: disc herniations, discogenic pain, and idiopathic deformities.