Understanding of peptic ulcer changed radically with the discovery of the role of
Helicobacter pylori. The media have been buzzing recently proclaiming a similar landmark following the publication of two studies from Denmark on disc infection with skin bacteria: ‘Millions ... could be cured by a simple and cheap course of antibiotics ... revolutionary ... the stuff of Nobel prizes.’ This clearly merits attention, some scrutiny and more work to clarify and confirm. In the meantime we will attempt to provide a useful digest for when patients present to their GP asking whether antibiotics might be helpful for their back pain. 1
The first paper concerned infection of disc material and subsequent development of what is called Type 1 Modic change (MC – representing bone oedema) on subsequent MRI scan. 61 patients undergoing surgical treatment for lumbar disc herniation had disc material sampled for culture. 28 patients (46%) had positive cultures – 26 with anaerobic and 2 with aerobic bacteria; 4 patients had both. In 86% of anaerobic cultures the skin commensal 2 Propionibacterium acnes was isolated. Of the patients with anaerobic cultures 80% developed new MC in the vertebrae adjacent to the disc surgery on subsequent MRI. Neither of the patients with aerobic cultures developed MC. Of the 33 patients with negative cultures 40% developed new MC. MC on MRI occurs in 6% of the general population and in 30–40% of people with low back pain (LBP), usually in association with degenerative discs. The aetiology, natural history and clinical relevance of MC is much debated and this study adds an extra dimension to the debate.
The second paper describes an RCT in which 162 patients with chronic (>6 months) LBP after disc herniation, and new Type 1 MC on MRI, were treated with 100 days of antibiotics (a combination of amoxycillin and clavulanate) or placebo. Multiple outcome measures were used. Subjects were assessed at 100 days and 1 year; 147 patients completed the study. There were some impressive reductions in pain, disability scores and time off work in the antibiotic group at 1 year compared with placebo. The volume of MC diminished in the antibiotic group but not the placebo group. The authors hypothesise that infection of intervertebral discs with 3 P. acnes results in propionic acid diffusing into adjacent bone, causing oedema, pain and Type 1 MC on MRI. They are appropriately cautious in their statements about the widespread prescription of long-term (no – not ‘simple’) antibiotics to all patients with chronic LBP. This study only looked at patients with chronic LBP after disc herniation so the statement ‘millions could be cured’ might be over-optimistic! However this is a very interesting line of research and we look forward to reporting more developments.