Spontaneous pyogenic vertebral osteomyelitis and endocarditis: incidence, risk factors, and outcome

The relationship between pyogenic vertebral osteomyelitis and infectious endocarditis is uncertain. This study investigates the incidence and risk factors of infectious endocarditis in patients with pyogenic vertebral osteomyelitis, and the outcome of pyogenic vertebral osteomyelitis with and without associated infectious endocarditis.

A retrospective record review was conducted of all cases of vertebral osteomyelitis from January 1986 to June 2002, occurring in a tertiary referral hospital. Patients were followed for at least 6 months with careful attention to detection of infectious endocarditis and relapses.

Among 606 patients with infectious endocarditis, 28 (4.6%) had pyogenic vertebral osteomyelitis. Among 91 cases of pyogenic vertebral osteomyelitis, 28 (30.8%) had infectious endocarditis. In 6 patients with no clinical signs of infectious endocarditis, the disease was established by routine echocardiography. Infectious endocarditis was more common in patients with predisposing heart conditions and streptococcal pyogenic vertebral osteomyelitis infection. Overall, pyogenic vertebral osteomyelitis in-hospital mortality was 11% (7.1% with infectious endocarditis). Twelve of 25 patients with infectious endocarditis with uncomplicated pyogenic vertebral osteomyelitis were treated for 4 to 6 weeks (endocarditis protocol), with no pyogenic vertebral osteomyelitis relapses.

When specifically sought, the incidence of infectious endocarditis is high in patients with pyogenic vertebral osteomyelitis. Oral therapy may be an option for uncomplicated pyogenic vertebral osteomyelitis; nevertheless, in gram-positive infections, this approach should only be considered after excluding infectious endocarditis. Favorable outcome with shorter treatment in uncomplicated pyogenic vertebral osteomyelitis associated with infectious endocarditis suggests that prolonged therapy may not be needed in this subgroup except for those infected by difficult to treat microorganisms, such as methicillin-resistant Staphylococcus aureus or Candida spp.