osteomyelitis
OSTEOMYELITIS
Osteomyelitis is an acute or chronic inflammation of the bone due to an infection resulting from hematogenous spread, contiguous spread from soft tissues and joints to bone, or direct inoculation into bone from surgery or trauma.
The infection is generally due to a single microorganism but polymicrobial infections may also occur.
Staphylococcus aureus is a major cause of infection.
Signs and symptoms include fever; inflammatory findings of erythema, warmth, pain and swelling over the involved area; draining sinus tracts over affected bone; limited movement of affected extremity; pain in the chest, back, abdomen or leg, and tenderness over involved vertebrae in patients with vertebral osteomyelitis; anorexia, vomiting and malaise.

Definition

  • Osteomyelitis is an acute or chronic inflammation of the bone due to an infection resulting from hematogenous spread, contiguous spread from soft tissues & joints to bone, or direct inoculation into bone from surgery or trauma
    • Infection is generally due to a single microorganism but polymicrobial infections may also occur

Etiology

Staphylococcus aureus is the most common cause of acute or chronic hematogenous osteomyelitis in children & adults

Common Pathogens in Osteomyelitis

Acute Hematogenous Osteomyelitis (AHO)

  • S aureus is the most common etiologic agent in children & adults
    • Children w/ community-acquired Methicillin-resistant S aureus (CA-MRSA) infection are more likely to have prolonged fever & be hospitalized for longer periods than children infected w/ Methicillin-sensitive S aureus (MSSA)
    • Children w/ Methicillin-resistant S aureus infection are more likely to have multiple foci of infection as well as subperiosteal & intraosseous abscesses
  • Other causes of acute hematogenous osteomyelitis in children include Streptococcus pneumoniae, S pyogenes, Kingella kingae; rarely, Escherichia coli & other gram-negative enteric bacilli, Pseudomonas aeruginosa, Haemophilus influenzae type B, anaerobes
  • IV drug abusers are more prone to infections by P. aeruginosa, Serratia marcescens, S aureus, Salmonella spp & fungal organisms
  • Fungi may be the cause of osteomyelitis in neonates, patients who are immunocompromised eg w/ prolonged neutropenia, those w/ chronic granulomatous disease, catheter-related fungemia, or are in geographic locations indigenous for certain fungal diseases

Contiguous-Infection Osteomyelitis

  • Among patients w/o generalized vascular insufficiency, S aureus is most frequently isolated from bone, but multiple pathogens may also be isolated including gram-negative bacilli & anaerobes
  • Among patients who have generalized vascular insufficiency, esp those w/ DM, multiple pathogens are usually isolated from bone, most commonly coagulase-positive & negative staphylococci,Streptococcus spp, Enterococcus spp, gram-negative bacilli & anaerobes
  • Anaerobic organisms are common in patients w/ risk factors including surgery, trauma, DM, decubitus ulcers, human bites, chronic otitis media or sinusitis, dental infection, prosthetic devices, fibrous dysplasia of the bone

Vertebral Osteomyelitis

  • S aureus is the most frequently isolated pathogen
  • Spondylitis is the most common form of Mycobacterium tuberculosis musculoskeletal infection & should be suspected if symptoms & x-rays indicate chronic infection
  • E coli may be an etiologic agent in adults esp those w/ a history of recent urinary tract infection or instrumentation
  • IV drug abusers are more prone to infections due to P aeruginosa, S aureus, Serratia spp, Klebsiellaspp, Enterobacter spp, or Candida spp

Signs and Symptoms

  • Fever
  • Inflammatory findings of erythema, warmth, pain, & swelling over the involved area
  • Draining sinus tracts over affected bone
  • Limited movement of affected extremity
  • Pain in the chest, back, abdomen or leg, & tenderness over involved vertebrae in patients w/ vertebral osteomyelitis
  • Anorexia, vomiting, malaise

Risk Factors

  • Chronic wounds w/ exposed bone, tissue necrosis, underlying open fractures or underlying internal fixation
  • Advanced age
  • Diabetes mellitus (DM)
  • Immunosuppression
  • IV drug abuse
  • Organ transplantation
  • Malnutrition
  • Cancer
  • Renal or hepatic impairment
  • Chronic hypoxia
  • Peripheral vascular disease
  • Radiation fibrosis
  • Neuropathy
  • Tobacco consumption >2 packs/day
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