• Osteomyelitis (OM): Infection of bone with ongoing inflammatory destruction
  • Usually bacterial, but fungal OM does occur
  • Classified as acute or chronic, hematogenous, or nonhematogenous


  • Hematogenous OM:
    • Primarily in children, elderly, IV drug abuse (IVDA) patients
    • Seeding of bacteria to bone from remote site of infection via bloodstream
    • Children commonly have acute OM and adults more often subacute or chronic
    • Hematogenous OM of long bones rarely occurs in adults
    • Most children with acute hematogenous OM have no preceding illness
    • 1/3 have history of trauma to affected area
    • Staphylococcus aureus is the most common cause of OM in all ages
    • Neonates: S. aureus, Enterobacteriaceae, group A and B streptococci, and Escherichia coli
    • Children: S. aureus, group A streptococci, Haemophilus influenzae, Enterobacteriaceae
    • Salmonella: Common in sickle cell disease
    • Adults: S. aureus, Enterobacteriaceae, Pseudomonas, gram-negative rods, Staphylococcus epidermidis, gram-positive anaerobes, especially Peptostreptococcus
    • Illicit drug users: Candida, Pseudomonas, Serratia marcescens
    • Prolonged neutropenia: Candida, Aspergillus, Rhizopus, Blastomyces, coccidioidomycosis
  • Hematogenous vertebral OM:
    • Uncommon
    • Most prevalent in adults >45 yr
    • Involves the disk and vertebra above and below
    • Often in the setting of long-term urinary catheter placement, IVDA, cancer, hemodialysis, or diabetes
    • IVDA: OM of pubic symphysis, sternoclavicular, and sacroiliac (SI) joints
    • Lumbar vertebrae most common, followed by thoracic, then cervical
    • Posterior extension leads to epidural/subdural abscess or meningitis
    • Anterior extension may lead to paravertebral, retropharyngeal, mediastinal, subphrenic, retroperitoneal, or psoas abscess
  • Direct or contiguous OM:
    • Organism(s) directly seeded in bone due to trauma, especially following open fractures:
      • Spread from adjacent site of infection or poorly healing soft tissue wound
    • More common in adults and adolescents
    • S. aureus, Enterobacteriaceae, Pseudomonas
    • Normal vascularity:
      • S. aureus and S. epidermidis, gram-negative bacilli, and anaerobic organisms
    • Vascular insufficiency/diabetes:
      • Small bones of feet are common sites
      • Infection resulting from minor trauma, infected nail beds, cellulitis, or skin ulceration
      • Polymicrobial, including anaerobes
    • Puncture wound through tennis shoe: S. aureus, Pseudomonas
    • Clavicular OM can occur as complication of subclavian vein catheterization
  • Chronic OM:
    • OM that persists or recurs
    • Distinguishing characteristic is necrotic bone (sequestrum) that must be débrided
    • S. epidermidis, S. aureus, Pseudomonas aeruginosa, S. marcescens, and E. coli

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