Diabetic Foot Osteomyelitis

1. See Also
   1. Osteomyelitis
   2. Osteomyelitis Management
2. Differential Diagnosis
   1. Cellulitis
   2. Charcot Foot
3. Findings: Red Flags suggestive of Foot Osteomyelitis
   1. Sausage toe (swollen, deformed red toe)
   2. Bone Visualized or Probe-to-Bone Test positive
   3. Skin ulcer with red flags
      1. Infected ulcer with ESR >70 mm/h or unexplained Leukocytosis
      2. Non-healing ulcer despite several weeks of wound care and non-weight bearing
      3. Non-healing ulcer over bony prominences despite wound care
      4. Ulcer with underlying bony XRay changes
      5. Ulcer area >2 cm^2
      6. Ulcer depth >3 mm
4. Classification: Diabetic Foot Ulcer
   1. See Wagner Ulcer Classification
   2. See University of Texas Diabetic Wound Classification
5. Grading: Osteomyelitis Severity
   1. Not infected
      1. Wound without purulence or inflammation
   2. Mild Infection
      1. Wound with purulence and inflammation
      2. Localized infection that does not extend more than 2 cm beyond ulcer margins
   3. Moderate Infection
      1. Regional infection extending more than 2 cm beyond ulcer margins
      2. Ascending lymphangitis with deep infection
   4. Severe Infection
      1. Sepsis
6. Evaluation
   1. Evaluate foot neurovascular status
   2. Bone Visualized or Probe-to-Bone Test positive
      1. Treat as presumptive Osteomyelitis
   3. Osteomyelitis XRay consistent with Osteomyelitis
      1. Treat as presumptive Osteomyelitis
   4. Osteomyelitis XRay not consistent with Osteomyelitis
      1. Severe Peripheral Neuropathy or high suspicion
         1. Obtain Osteomyelitis Bone Scan or Osteomyelitis Bone MRI
            1. Positive: Treat as presumptive Osteomyelitis
            2. Negative: Treat as Soft Tissue infection
      2. Lower suspicion for Osteomyelitis
         1. Treat as Soft Tissue Infection
7. Management: General
   1. Wound Care
      1. Cleanse and debride wound
      2. Unload the wound (e.g. non-weight bearing)
      3. Consider Wound Healing agents
      4. Evaluate foot wear
      5. Obtain wound culture and Gram Stain
   2. Mild to moderate infections
      1. Choose parenteral or oral agents as below
      2. Reevaluate every 2-3 days until improving
      3. Treat as severe infection if lack of improvement
   3. Severe infections
      1. Hospitalize and treat with parenteral agents
      2. Obtain deep wound culture (consider bone biopsy and culture)
      3. Reevaluate twice daily
      4. Consider orthopedic surgery for bone biposy or resection
      5. Consider vascular surgery for revascularization considerations
      6. Consider hyperbaric oxygen or Granulocyte stimulating factors
8. Management: Antibiotic Course
   1. Soft tissue infection
      1. Mild Foot Infection: 1-2 week total course
      2. Moderate Foot Infection: 2-4 week total course
      3. Severe Foot Infection: 2-4 week total course
   2. Bone infection
      1. Residual infected viable bone: 4-6 week total course
      2. Residual infected dead bone: 8-12 week total course
9. Management: Antibiotic Choice
   1. Mild Foot Infection
      1. Dicloxacillin 500 mg orally four times daily (first-line for MSSA)
      2. Cephalexin 500 mg orally four times daily (Penicillin allergic patients with MSSA)
      3. Augmentin 875 mg orally twice daily (polymicrobial infections)
      4. Clindamycin 450 mg orally three times daily
      5. Doxycycline 100 mg orally twice daily
      6. Septra DS orally twice daily
   2. Moderate Foot Infection without polymicrobial risks
      1. Nafcillin 1-2 grams IV every 4 hours (first-line for MSSA)
      2. Cefazolin 1-2 grams IV every 8 hours (Penicillin allergic patients with MSSA)
      3. Vancomycin 30 mg/kg IV every 12 hours (first-line for MRSA)
   3. Moderate Foot Infection and polymicrobial risks (chronic ulcer, foot ischemia, recent antibiotics)
      1. Unasyn 3 grams IV every 6 hours
      2. Ceftriaxone 1-2 grams IV every 24 hours
         1. plus every 8 hours IV, Clindamycin 600-900 mg or Metronidazole 500 mg
      3. Levofloxacin 500 mg IV or orally every 24 hours
         1. plus Clindamycin 600-900 mg IV or orally every 8 hours
      4. Moxifloxacin 400 mg IV or orally daily
      5. Ertapenem 1 gram IV every 24 hours
   4. Severe Foot Infection
      1. Ciprofloxacin 400 mg IV every 12 hours
         1. plus Clindamycin 600-900 mg IV every 8 hours
      2. Zosyn 3.375 to 4.5 grams IV every 6-8 hours
      3. Primaxin 500 mg IV every 6 hours
      4. Vancomycin 30 mg/kg IV every 12 hours (first-line for MRSA)
         1. plus Ciprofloxacin 400 mg IV every 12 hours
         2. plus Metronidazole 500 mg IV every 8 hours
      5. Tygacil 100 mg IV load and then 50 mg IV every 12 hours (polymicrobial infections, MRSA)
10. References
    1. Bader (2008) Am Fam Physician 78:71-9
    2. Lipsky (2004) Clin Infect Dis 39:885-910
    3. Lipsky (1997) Clin Infect Dis 25:1321