Epidemiological and clinical features of pyogenic spondylodiscitis.

Pyogenic spondylodiscitis (PS) is an uncommon but important infection, that represents 3-5% of all cases of osteomyelitis. The annual incidence in Europe has been estimated to be from 0.4 to 2.4/100,000. A has been reported, with peaks at age less than 20 years and in the group aged 50-70 years. The incidence of PS seems to be increasing in the last years as a result of the higher life expectancy of older patients with chronic debilitating diseases, the rise in the prevalence of immunosuppressed patients, intravenous drug abuse, and the increase in spinal instrumentation and surgery. PS is in most cases a hematogenous infection. Staphylococcus aureus is the most frequent causative microorganism, accounting for about one half of the cases of PS. Gram-negative rods are causative agents in 7-33% of PS cases. Coagulase-negative staphylococci (CoNS) have been reported in 5-16% of cases. Staphylococcus epidermidis is often related to post-operative infections and intracardiac device-related bacteremia. Unremitting back pain, characteristically worsening during the night, is the most common presenting symptom, followed by fever that is present in about one half of the cases. The mortality of PS ranges from 0 to 11%. In a significant number of cases, recrudescence, residual neurological defects or persistent pain may occur.