Osteomyelitis is caused by a bacterial infection of the bone. The bacteria may enter the bone through an open injury to the skin, during surgery on the bone, or from the bloodstream.

The most common bacteria that cause osteomyelitis include:

• Staphylococcus aureus
• Staphylococcus epidermidis
• Streptococci
• E. coli
• Proteus

Vertebral osteomyelitis is a relatively uncommon infection that occurs primarily in adults over the age of 50. Vertebral osteomyelitis is often caused by a staphylococcus infection. Medical instrumentation, medical procedures, and spine surgery are considered to be risk factors for acquiring vertebral osteomyelitis.