The shock finding means that scores of patients with unrelenting lower back pain will no longer face major operations but can instead be cured with courses of antibiotics.
One of the UK's most eminent spinal surgeons said the discovery was the greatest he had witnessed in his professional life, and that its impact on medicine was worthy of a Nobel prize.
"This is vast. We are talking about probably half of all spinal surgery for back pain being replaced by taking antibiotics," said Peter Hamlyn, a consultant neurological and spinal surgeon at University College London hospital.
Specialists who deal with back pain have long known that infections are sometimes to blame, but these cases were thought to be exceptional. That thinking has been overturned by scientists at the University of Southern Denmark who found that 20% to 40% of chronic lower back pain was caused by bacterial infections.
Claus Manniche, a senior researcher in the group, said the discovery was the culmination of 10 years of hard work. "It's been tough. There have been ups and downs. This is one those questions that a lot of our colleagues did not understand at the beginning. To find bacteria really confronts all we have thought up to this date as back pain researchers," he said.