Chronic osteomyelitis

Background

• Osteomyelitis that involves necrotic bone, usually suggested by treatment failure, symptoms lasting three or more weeks, presence of sequestrum, persistent drainage, or sinus tract

Microbiology

• Staphylococcus aureus
• Coagulase-negative staphylococci
• Streptococcus
• Enterococcus
• Pseudomonas aeruginosa
• Gram-negative Enterobacteriaceae
• Anaerobes including Cutibacterium acnes
• Unusual pathogens:
  • After animal bite: Pasteurella multocida, Eikenella corrodens
  • If risk factors: tuberculosis
  • Non-tuberculous mycobacteria
  • Fungi

Investigations

• CT is better than MRI for imaging for bony sequestrum1

Management

• Ideally get bone biopsy for culture prior to starting antibiotics
• In general, typically treated with 4 to 6 weeks of parenteral or highly bioavailable therapy followed by step-down to oral therapy to complete total of 4 to 12 weeks
  • TMP-SMX or a fluoroquinolone is preferred oral therapy
  • There is no evidence that antibiotic therapy longer than 4 to 6 weeks improves outcomes2
• Some recommend adding rifampin for Staphylococcus aureus, especially if hardware is involved