Is a bug the reason for your bad back?


Could a common microbe be the cause of your back pain? A chance discovery by researchers in Birmingham suggests that hidden infection by bacteria usually associated with acne could be to blame for up to half of all cases of sciatica.

It's the first time infection has been implicated in the condition, which causes persistent and sometimes excruciating lower back and leg pain. Usually it's blamed on a 'slipped' or herniated spinal disc pressing on the sciatic nerve, but in some cases there is no evidence of abnormal nerve pressure, while many cases of herniated discs are symptom-free.

Researchers stumbled across the finding during trials of a new blood test designed to pick up signs of chronic low-grade infection. Study leader Dr Tom Elliott, professor of microbiology at University Hospital in Birmingham, says his team found evidence of deep-seated infection in a large percentage of sciatica patients, who were being used as a control group during the trials.

'The results surprised us because this group wasn't supposed to show any signs of infection,' says Dr Elliott. 'None of them had had an infection in the past six months.'

Follow-up tests on disc tissue taken from sciatica sufferers revealed the culprit to be Propionibacterium acnes, a slow-growing bacteria commonly associated with acne and routinely found on the skin and in the blood.

'Generally it's considered fairly harmless in healthy people,' says Dr Elliott, 'but it's increasingly being recognised as an agent of infection. We think that minor trauma to the disc, say slight damage as a result of lifting something heavy, provides the bacteria with an ideal resting place.'

Dr Elliott believes the bacteria then colonise the site of the injury causing chronic infection and inflammation, leading to sciatic pain.

The P. acnes bacterium is known to cause infections in artificial hip replacements and catheter wounds, but Dr Elliott says it's likely its role in other infections is often missed simply because it is so slow-growing.

'Lab cultures are traditionally done over 48-72 hours, but P. acnes takes up to seven days to grow - long after most culture plates are destroyed.'

Current treatment for sciatica centres on physiotherapy, exercise, pain management and, in extreme cases, surgery, but the Birmigham team's findings indicate that antibiotics may have a role.

Dr Elliott is already planning the next phase of research, and says the team will examine, among other things, whether antibiotics can clear up disc infections and whether this has any effect on sciatic pain.

Spinal specialist Mr Philip Sell, a consultant orthopaedic surgeon at the University Hospitals of Leicester NHS Trust, says the Birmingham team's findings are very exciting.

'The research needs to be independently verified, of course, but if infection is identified as a cause of sciatica, it would be a finding on par with the discovery of Helicobacter pylori's role in gastric ulcers.'

That discovery, which showed that bacterial infection rather than stress and lifestyle was to blame for most cases of gastric ulcer, has revolutionised ulcer treatment and greatly reduced the need for surgery.

However, Mr Sell said it was too early to say whether bacteria was definitely to blame for those cases of sciatica where infection was present.

'It might be that infection leads to sciatica, as the Birmingham team say, but it could also be the case that sciatica somehow predisposes a disc to infection.

'That said, I hope other units follow up this research. It would be marvellous to find a way to treat extreme sciatica non-operatively.'

According to Back Care, the national charity that funded the study, lower back pain, including sciatica, is currently the number one cause of disability in the UK.

Some 180 million working days are lost each year to the problem, and 13 per cent of unemployed people say back pain is the reason they are not working.