The microorganisms that affect the spine are usually bacteria (staphylococci), and, on some occasions, fungi. Generally, there is a history of infection in other areas of the body (genitourinary, skin, respiratory tract) that, through the blood (hematogenous spread) is implanted in the vertebra or in the intervertebral disc.
One of the most common reasons for infections in the vertebrae or in the intervertebral disc is post-surgery, after performing open surgery on the spine. In this case, the lesion is more favored in immunosuppressed patients (immune system that functions below the normal rate), diabetics, chronic pathologies, obesity, smokers, anemic or malnourished, and when long-term surgeries are performed. It can be an infection in superficial planes that causes an opening of the surgical wound, or it can infect deep planes with involvement of the muscles, fasciae, ligaments, vertebrae, and intervertebral disc.
Other causes may be injuries near the spinal column or penetration of contaminated foreign bodies to these structures.