Chronic low back pain: could an anaerobic infection be responsible?
Around 80% of people in Western countries experience low back pain at some point in their life; indeed during a single year up to half of the adult population will experience back pain. In the majority no single clear cause can be identified, and the condition is self limiting. However for the approximately 7% of patients who develop chronic low back pain, quality of life can be significantly impaired. Chronic low back pain also has a serious financial impact in terms of healthcare costs and lost working days; in most industrialized countries it is the most common reason for workplace absence.
Now researchers at the Spine Centre of Southern Denmark have published the results of two very interesting and potentially far-reaching studies. The first involved sixty-one patients who had been suffering from low back pain for more than six months. Lumbar disc herniation was confirmed by MRI and the patients underwent primary surgery for removal of nucleus material. When this material was cultured for micro-organisms, forty-six percent of patients had positive cultures, predominantly with the normally commensal anaerobic bacterium Propionibacterium acnes. A significantly higher number of patients with anaerobic infections developed new Modic changes (MC), MRI-visible bone edema associated with low back pain, in vertebrae adjacent to the previous disc herniation compared with patients with negative cultures or cultures positive for aerobic organisms.
The second study was a double blind randomized controlled trial involving 162 patients who had been suffering from low back pain for more than six months and with MC in a disc adjacent to a previous disc herniation. Patients received either placebo or the antibiotic Bioclavid for a hundred days and were followed up at the end of treatment and after one year; outcome measures included both pain and workplace absence. Improvement was highly significant in the group treated with the antibiotic.
The authors suggest that when the lumbar disc is herniated, the anaerobic bacteria penetrate it and precipitate an insidious infection and chronic low back pain. Although they stress that antiseptic techniques were rigorously followed when the nucleus material was removed, it is surely still necessary to find a method of demonstrating anaerobic infection in patients who have low back pain and relevant MC but who have not had surgery. If this could be done many desperate chronic lower back pain sufferers might finally be able to stop taking analgesics or visiting osteopaths, chiropractors and acupuncturists, and get relief from a course of antibiotics instead.