What is the appropriate workup and treatment for Osteomyelitis (infection of the bone)?

From the Guidelines

Osteomyelitis workup and treatment should prioritize a combination of clinical evaluation, laboratory tests, and imaging studies, with a focus on identifying the causative organism and guiding targeted antimicrobial therapy, as recommended by the most recent guidelines 1. The workup should begin with a thorough history and physical examination, followed by laboratory tests including complete blood count, erythrocyte sedimentation rate, and C-reactive protein.

• Blood cultures should be obtained before starting antibiotics
• Imaging studies are essential, starting with plain radiographs
• MRI is the most sensitive imaging modality and should be performed when the diagnosis remains in doubt despite clinical and laboratory findings 1. Some key points to consider in the workup and treatment of osteomyelitis include:
• The use of conventional microbiology techniques for the first-line identification of pathogens from soft tissue or bone samples 1
• The consideration of a combination of probe-to-bone test, plain X-rays, and ESR, or CRP, or PCT as the initial studies to diagnose osteomyelitis of the foot 1
• The importance of bone (rather than soft tissue) samples for culture, either intraoperatively or percutaneously, in patients with suspected osteomyelitis of the foot 1
• The recommendation to use any of the systemic antibiotic regimens that have been shown to be effective in published randomized controlled trials at standard dosing to treat soft tissue infections of the foot 1
• The administration of antibiotic therapy for a duration of 1–2 weeks, with consideration of continuing treatment for up to 3–4 weeks if the infection is improving but is extensive and is resolving slower than expected or if the patient has severe peripheral artery disease (PAD) 1 Treatment requires a multidisciplinary approach combining surgical debridement and antimicrobial therapy, with a focus on removing necrotic tissue, draining abscesses, and improving antibiotic penetration, as well as regular follow-up with serial inflammatory markers to monitor treatment response 1.

From the Research

Osteomyelitis Workup

• The workup for osteomyelitis typically involves identifying the offending organism(s) and determining the extent of the infection 2
• Imaging tests such as magnetic resonance imaging and bone scintigraphy can be used to characterize the infection, while plain radiography can help identify alternative diagnoses and potential complications 2
• Direct sampling of the wound for culture and antimicrobial sensitivity is essential to target treatment 2

Osteomyelitis Treatment

• The treatment of osteomyelitis usually involves a combination of surgical debridement and antibiotic therapy 3, 2
• The choice of antibiotic therapy depends on the offending organism(s) and the severity of the infection, with empiric coverage for Staphylococcus aureus often indicated 3, 2
• The duration of antibiotic treatment can vary, but typically ranges from 4-6 weeks for acute hematogenous osteomyelitis in children, and several weeks longer for chronic osteomyelitis in adults 3, 2
• Oral antibiotic therapy may be as effective as intravenous treatment for osteomyelitis, especially for cases with gram-positive bacteria 4
• However, the effectiveness of antibiotic therapy can be limited by the ability of S. aureus to adapt to a reversible quiescent state that is protected against antibiotics 5

Factors Affecting Treatment Outcome

• The presence of polymicrobial infections and treatment durations of less than six weeks can increase the risk of treatment failure 4
• The recurrence rate of osteomyelitis remains high despite surgical intervention and long-term antibiotic therapy 2
• The increased incidence of methicillin-resistant Staphylococcus aureus osteomyelitis can complicate antibiotic selection 2