Abstract
Background
Recently, some studies have focused attention on the possibility that anaerobic pathogens of low virulence could constitute an etiological factor in disc herniation. There have been isolated such strains, predominantly Propionibacterium acne, between 7 and 53% of patients undergoing surgery for disc pathology. According to these studies, patients with anaerobic infections of the disc are more likely to develop Modic changes in the adjacent vertebrae. The aim of this work was to test this hypothesis by growing in specific media the disc material extracted in a series of lumbar discectomy and relating this factor with the presence of pre-intervention Modic changes.
Methods
A total of 22 consecutive patients undergoing primary unisegmental discectomy for lumbar disc herniation (77.2% male, mean age 40.1 ± 9.1 years) were included. All patients were immunocompetent and none had previously received an epidural steroid injection prior surgery. MRI study confirmed the disc herniation. Following strict antiseptic protocols, the extracted disc material was sent for slow-growth anaerobic enriched culture (>10 days).
Results
In total, anaerobic cultures were positive in 7 cases (31.8%) all men. In 5 of these cases, the symptoms developed with an acute onset. The isolated germs were always unique: Propionibacterium acne (3), Streptococcus parasanguinis (1), Actinomyces naeslundii (1), Actinomyces meyeri (1) and methicillin sensitive Staphylococcus epidermidis. Only two (28.6%) of these 7 patients had Modic changes on MRI prior surgery (one type I, one type 2). None of the patients with negative cultures had Modic changes.
Conclusions
These findings support the theory that anaerobic infections of low virulence and slow growth may contribute to the pathogenesis of herniated discs. However, these cases do not necessarily develop type 1 Modic changes as previously speculated.
Level of evidence
Level IV
