Acute Osteomyelitis
System: Bone and Joint Infections · Parent MOC: MOC - Diseases by System
One-Sentence Definition
Acute infection of bone, usually hematogenous in children and contiguous or hematogenous in adults, most often due to S. aureus.
Clinical Presentation
- Localized bone pain, fever, reduced use of limb; sinus tract in subacute/chronic
- Vertebral: back pain ± neurologic deficits; IVDU / bacteremia history
- Contiguous: trauma, ulcer (diabetic foot), surgery/hardware
Pathogens
| Context | Organism | Notes |
|---|---|---|
| All ages, #1 | Staphylococcus aureus | Incl. MRSA |
| Children | Kingella, strep (TBD) | Age patterns |
| Sickle cell | Salmonella (TBD) | Classic association |
| Diabetic foot / contiguous | Polymicrobial ± Pseudomonas aeruginosa | Deep culture after debridement |
| Hardware | CoNS, Cutibacterium (TBD) | Biofilm · Device-Associated Infections |
Pathogenesis
- Hematogenous seeding of metaphysis/vertebrae or contiguous spread
- Sequestrum/involucrum if becomes chronic
Diagnosis
| Step | Test | Note |
|---|---|---|
| Labs | CBC, CRP/ESR | Supportive |
| Micro | Blood cultures; bone biopsy culture before abx when stable | Gold specimen = bone |
| Imaging | MRI preferred for acute; X-ray late; bone scan adjunct |
Treatment Principles
- Culture-guided IV→PO therapy; duration typically weeks (guideline/syndrome-specific)
- Surgical debridement when abscess, dead bone, hardware infection, failure
- Empiric cover S. aureus (± MRSA) pending data
Prevention
- Treat bacteremia sources; pressure-offloading / ulcer care; perioperative prophylaxis when indicated
Differential / Pitfalls
- Fracture, infarct (sickle cell), tumor, chronic Charcot
- Superficial swab of ulcer ≠ bone microbiology
Learning Aids
Clinical Example
Example
Case: Teen with fever and focal tibial point tenderness; MRI confirms marrow edema.
Question: Most likely organism and ideal culture?
Answer: Staphylococcus aureus. Blood cultures + bone biopsy culture before antibiotics if it won’t clinically harm delay.
Related
Active Recall
- Most common overall bacterial cause?
- Why avoid relying on ulcer surface swabs?
- When is surgery required?