Vertebral osteomyelitis.

Vertebral osteomyelitis can be caused by a variety of microorganisms. The hematogenous pyogenic form is characteristically a disease of people over age 50, predominantly in the male population, and most frequently caused by S. aureus. In IVDAs, however, younger patients and a heavier predominance of males are seen, and P. aeruginosa is one of the most commonly seen pathogens. The disease is generally monomicrobial, unless it is secondary to a contiguous process such as a pressure sore, in which polymicrobial infection with participation of anaerobes is the general rule. Lumbar, greater than thoracic, greater than cervical involvement is the rule in the general population, but cervical spine involvement is frequently seen more often than thoracic involvement in IVDAs. Diabetic patients are over-represented among patients with vertebral osteomyelitis, and they also have a tendency for higher morbidity and mortality. Simultaneous involvement of adjacent vertebral end plates and the intervening disk is the general rule. The vertebrae are generally involved, and the posterior elements of the spine are involved infrequently. Posterior element involvement is seen more commonly in actinomycosis, coccidioidomycosis, and neoplasms. Newer diagnostic modalities, such as CT, MRI, and radionuclide scans, may detect the disease earlier than conventional radiographs. Immunobilization by bed rest and appropriate antimicrobial therapy are generally sufficient in the therapy of pyogenic, as well as tuberculous, vertebral osteomyelitis. In selected circumstances, such as in the presence of marked instability of the spine, the presence of new neurologic deficits, or with progression of previous neurologic deficits, surgical intervention may be necessary. With prompt diagnosis and proper management, the prognosis should generally be good.