Antibiotic treatment may bring relief to certain patients who have chronic low back pain, according to a Danish study published recently in the European Spine Journal. But that claim has some back specialists skeptical.

Low back pain is so common in the United States that the National Institutes of Health (NIH) says nearly everyone will experience it at some point in their lives. There are many potential causes for lower back pain, but a main one is aging. As we grow older, the discs that cushion the bones (vertebrae) along the spine dry out a bit, flatten and lose their ability to cushion.

Arthritis – both osteoarthritis as well as inflammatory types such as rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis – can affect the bones in the spine, pelvis and sacrum, leading to stiffness, swelling and pain. Back pain can also be caused by a damaged muscle, a pinched nerve or spinal stenosis, in which the spinal canal narrows and compresses the spinal cord. Lower back pain is called chronic when the pain lasts more than three months.

In a second, small study published in the same journal, the Danish researchers argue that in some cases – when a patient has had a herniated disc in the lower back – that patient’s chronic low back pain is caused by a bacterial infection in nearby vertebrae. Standard treatment for bacterial infections of any kind is antibiotics.

For the double-blind randomized trial, the researchers (from the Spine Center of Southern Denmark and from Aarhus University Hospital) looked at 162 patients who experienced chronic low back pain lasting at least six months after having a herniated disc and bone swelling (called vertebral bone edema). The patients were treated with the antibiotic amoxicillin (Bioclavid) or placebo for 100 days.

After a year, fewer than 68 percent of patients who took the antibiotic reported pain, compared with 94 percent of patients who took placebo. The researchers note the result is “highly statistically significant.” 

But antibiotics have side effects. Among the most common are upset stomach and diarrhea, which were issues in the study. Sixty-five percent of the patients said they had adverse effects, primarily stomach upset.

The idea of treating back pain with antibiotics is surprising to Edgar L. Ross, MD, the director of the Pain Management Center at Boston’s Brigham and Women’s Hospital. He likens this theory – if proven true – to the theory that identified bacteria in the gut (and not stress or spicy food) as the cause of stomach ulcers. That discovery, which turned conventional wisdom on its head, led to antibiotics becoming the standard treatment (instead of surgery) and to a Nobel Prize for the researchers.

Paul M. Cooke, MD, a physiatrist at the Hospital for Special Surgery in New York City, who specializes in non-surgical approaches to back pain, says the chances the antibiotic helped by treating a bacterial infection in the spine is “a low probability” and feels the results of this study are “far from convincing.”

“We have these same patients [as those in the study] and we treat them without antibiotics successfully. If a bacterial infection was the problem, we would be having no success,” Dr. Cooke says.

Current treatments for chronic back pain include anti-inflammatory and pain medication, physical therapy and exercise, lifestyle changes (which could include weight loss or quitting smoking), and steroid injections if there has not been improvement.     

Steven P. Cohen, MD, a professor of anesthesiology and critical care medicine at Johns Hopkins School of Medicine in Baltimore, Md., points out that the discs are mostly avascular – meaning they don’t have a large blood supply – and therefore don’t usually get infected unless it’s from a procedure. Furthermore, he says, if bacteria does get in, it’s very hard to get out, which likely explains why the study called for such a long course of treatment. 

Dr. Cohen calls the results so remarkable that they may be a case of “too good to be true” – a sentiment shared by Dr. Cooke and Dr. Ross.

Dr. Ross says the study is, “so out there, of course we would be uncomfortable and skeptical.” Adding that if this study can be replicated it could become the basis for a completely new way of treating chronic low back pain.

There could be several explanations for the findings other than eradicating a bacterial infection in the spine, says Dr. Ross. For example, antibiotics have anti-inflammatory properties.

The next step is more research.

In the meantime, Dr. Ross has this to say to patients hoping they’ve found the answer to their pain: “It’s interesting but there is no proof that this is an appropriate therapy for this kind of problem at this time.”