How can a person get an infection of a disk space in the spine?

Will

The spine is made up of bones called vertebrae, and disks that separate them. Much more blood supplies the disks than the bones themselves. Many diseases affect the spine. Most of these are arthritis conditions such as osteoarthritis, rheumatoid arthritis and ankylosing spondylitis, to name a few. Tumors and infections can also involve the vertebrae and the disks. When tumors involve the spine, they generally arise in other organs, such as the breast or the prostate. Malignancies such as these tend to involve the vertebral bones before spreading to the disks. Infections, on the other hand, usually involve the disks first and then the bones. For this reason, infection of the vertebral bones (vertebral osteomyelitis) usually involves a disk, often in the lumbar (lower) spine, and the vertebrae above and below it.

Bacteria are the most common causes of vertebral osteomyelitis. Fungi can also cause osteomyelitis, but I will not discuss it here, because it is quite uncommon. Staphylococcus aureus, or "staph," is the most common cause of vertebral osteomyelitis in normal hosts. In most cases, the illness starts when a patient develops a minor skin infection due to staph. The bacteria enter the bloodstream and for some reason set up an infection in an intervertebral disk, usually in the lower spine. This infection tends to worsen gradually, over weeks to months, with back pain and tenderness. Fever and other whole-body signs of infection are often absent.

Other types of bacteria can cause this infection. Intravenous drug users sometimes get infection with Pseudomonas, a group of bacteria that is particularly difficult to treat. Vertebral osteomyelitis can also follow urinary and prostate infections, particularly in the elderly. Mycobacterium tuberculosis can cause vertebral osteomyelitis, a syndrome known as Pott's disease. This frequently involves the vertebrae of the thorax (upper back), rather than the lumbar region, though any area can be involved. Like typical bacterial osteomyelitis, there are often no signs of infection outside the spine.

Osteomyelitis of the spine is usually treated with medication, but surgery is performed if the spine is unstable or if there are abscesses that require drainage. Otherwise, a long course of antibiotic, given intravenously, is usually sufficient for cure. Spinal tuberculosis is treated with the same regimen used for typical pulmonary (lung) TB -- six months or more of oral antibiotics.