There is debate as to the cause, although hematogenous seeding of the offending organism is favored as well as direct spread. It is important to differentiate between spontaneous discitis which is usually from hematologic spread from a urinary or respiratory infection versus that from a post-operative complication which usually involves skin flora such as staph aureus.

It can be caused due to spinal tuberculosis and spread along spinal ligament to involve the adjacent anterior vertebral bodies, causing angulation of the vertebrae with subsequent kyphosis.

The cause may be aseptic.

Spondylodiscitis is the most common complication of sepsis or local infection, usually in the form of an abscess. The main causative organisms are staphylococci and Mycobacterium tuberculosis, but potential organisms include a large number of bacteria, fungi, zoonoses. Spondylodiscitis frequently develops in immunocompromised individuals, such as by a cancer, infection, or by immunosuppressive drugs used for organ transplantations.

Discitis or diskitis is an infection in the intervertebral disc space that affects different age groups. In adults it can lead to severe consequences such as sepsis or epidural abscess but can also spontaneously resolve, especially in children under 8 years of age. Discitis occurs post surgically in approximately 1-2 percent of patients after spinal surgery.

The main methods to diagnose a spondylodiscitis are magnetic resonance imaging (MRI), biopsy and microbiological tests such as PCR to determine an infectious cause.

An abscess in the psoas muscle of the abdomen may be caused by lumbar tuberculosis. Owing to the proximal attachments of the iliopsoas, such an abscess may drain inferiorly into the upper medial thigh and present as a swelling in the region. The sheath of the muscle arises from the lumbar vertebrae and the intervertebral discs between the vertebrae. The disc is more susceptible to infection, from tuberculosis and "Salmonella discitis". The infection can spread into the psoas muscle sheath.

Treatment may involve drainage and antibiotics.