What is the management of osteomyelitis of the spine?

Management of Spinal Osteomyelitis

The management of spinal osteomyelitis requires a 6-week course of pathogen-directed antimicrobial therapy, combined with surgical intervention in cases of neurological compromise, spinal instability, or persistent infection despite medical therapy. 1, 2

Diagnosis

• Suspect native vertebral osteomyelitis (NVO) in patients with new or worsening back/neck pain accompanied by fever, elevated inflammatory markers (ESR/CRP), or recent bloodstream infection 3
• Obtain an image-guided aspiration biopsy in all patients with suspected NVO when a microbiologic diagnosis has not been established by blood cultures or serologic tests 3
• Exception: Biopsy may be deferred in patients with S. aureus or Brucella species bloodstream infection with compatible clinical and imaging findings 3
• Do not delay antimicrobial therapy in patients with sepsis or impending spinal cord compression 3

Antimicrobial Therapy

• Initial empiric therapy should target the most common pathogens, particularly S. aureus (including MRSA) and gram-negative organisms 2
• Recommended empiric regimen: vancomycin plus a third/fourth-generation cephalosporin or carbapenem 2
• Adjust therapy based on culture results and antimicrobial susceptibility testing 2
• Pathogen-specific recommendations:
  • MSSA: nafcillin/oxacillin, cefazolin, or ceftriaxone 2
  • MRSA: vancomycin, daptomycin, or linezolid 2
  • Gram-negative organisms: cefepime, ertapenem, or fluoroquinolones 2
  • Brucella: combination therapy with doxycycline plus streptomycin or rifampin 1

Duration and Route of Administration

• Standard duration is 6 weeks of antimicrobial therapy 1, 2
• Initial parenteral therapy is standard, with potential switch to oral antibiotics with good bioavailability (fluoroquinolones, linezolid, clindamycin) once clinical improvement occurs 1, 2
• Oral antibiotics with excellent bioavailability can be used without compromising efficacy 1
• Rifampin can be added to improve bone penetration and biofilm activity, but should be added after bacteremia has cleared to prevent resistance development 1

Surgical Management

• Surgical intervention is indicated for patients with: 1, 2, 4
  • Progressive neurologic deficits
  • Spinal instability
  • Progressive deformity
  • Persistent or recurrent bloodstream infection
  • Worsening pain despite appropriate medical therapy
  • Significant sequestered paraspinal or epidural abscess
• Consult with both a spine surgeon and infectious disease physician for optimal management 3

Monitoring Response to Therapy

• Follow clinical response and inflammatory markers (ESR, CRP) to guide therapy 1
• A 25-33% reduction in inflammatory markers after 4 weeks of therapy indicates reduced risk of treatment failure 3
• Unchanged or increasing inflammatory values after 4 weeks should raise suspicion for treatment failure 3
• Consider follow-up MRI with emphasis on evolutionary changes in paraspinal and epidural soft tissues in patients with suspected treatment failure 3
• Soft tissue findings on MRI may correlate better with clinical status than bone changes, which often appear worse despite clinical improvement 3

Management of Treatment Failure

• Signs of treatment failure include: persistent/recurrent severe back pain, systemic symptoms of infection, undrained abscess, or persistently elevated inflammatory markers 3
• Risk factors for treatment failure: diabetes mellitus, intravenous drug use, recurrent bloodstream infection, new-onset neurologic deficits, and sinus tract formation 3
• In cases of suspected treatment failure: 3
  • Obtain inflammatory markers (ESR, CRP)
  • Perform follow-up MRI focusing on soft tissue changes
  • Consider additional tissue sampling for microbiologic and histopathologic examination
  • Consult with a spine surgeon and infectious disease physician

Common Pitfalls to Avoid

• Delaying diagnosis by misinterpreting symptoms as degenerative disease 3
• Initiating empiric antimicrobial therapy before obtaining cultures (except in sepsis or neurologic compromise) 3
• Relying on wound swab cultures rather than bone cultures for pathogen identification 5
• Unnecessarily prolonged antibiotic courses, which increase risk of adverse effects and resistant pathogens 4
• Misinterpreting follow-up imaging performed too early (<4 weeks), which may falsely suggest progressive infection despite clinical improvement 4