Workup and Treatment for Left Lower Extremity Deep Tissue Infection with Severe Skin Erythema
For left lower extremity deep tissue infection with severe skin erythema, prompt initiation of broad-spectrum antibiotics active against Gram-positive, Gram-negative, and anaerobic bacteria is recommended, along with early surgical consultation for possible debridement and drainage. 1
Initial Assessment and Classification
Assess the severity of infection based on local and systemic signs to classify as mild, moderate, or severe 1:
- Class 1: No signs of systemic toxicity or comorbidities
- Class 2: Systemically unwell with stable comorbidities or systemically well with complicating comorbidities
- Class 3: Toxic appearance (fever, tachycardia, tachypnea, hypotension)
- Class 4: Sepsis syndrome and life-threatening infection (e.g., necrotizing fasciitis)
Evaluate for signs suggesting necrotizing infection requiring immediate surgical intervention 1, 2:
- Pain disproportionate to physical findings
- Violaceous bullae
- Cutaneous hemorrhage
- Skin sloughing or anesthesia
- Rapid progression
- Gas in tissue
Obtain laboratory tests for patients with systemic toxicity 1:
- Blood cultures
- Complete blood count with differential
- Creatinine, bicarbonate, creatine phosphokinase levels
- C-reactive protein
Diagnostic Workup
For all patients with deep tissue infection, obtain plain radiographs of the affected extremity to evaluate for bony abnormalities, soft tissue gas, or foreign bodies 1
Consider obtaining tissue specimens for culture and Gram stain via 1:
- Needle aspiration
- Tissue biopsy
- Swab of purulent drainage (less preferred)
For suspected osteomyelitis or deep tissue abscess, MRI is the imaging study of choice 1
For patients with severe infection, obtain blood cultures before starting antibiotics 1
Treatment Approach
Antibiotic Therapy
For moderate to severe infections with systemic signs, initiate broad-spectrum empiric antibiotics 1:
- Gram-positive coverage (including MRSA): Vancomycin (15 mg/kg IV every 12h), linezolid (600 mg IV/PO every 12h), or daptomycin (4-6 mg/kg IV daily) 3, 4
- Plus one of the following for Gram-negative/anaerobic coverage:
- Piperacillin-tazobactam (3.375 g IV every 6h or 4.5 g every 8h)
- Carbapenem (imipenem, meropenem, or ertapenem)
- Ceftriaxone (1 g IV daily) plus metronidazole (500 mg IV every 8h)
- Fluoroquinolone plus metronidazole 1
For documented group A streptococcal infection, use penicillin plus clindamycin 1, 2
Duration of therapy should be guided by clinical response, typically 5-14 days for soft tissue infections without osteomyelitis 1
Surgical Management
Surgical consultation is recommended for all patients with deep tissue infections and signs of systemic toxicity 1
Indications for surgical intervention include 1, 2:
- Abscess formation requiring drainage
- Extensive or advancing cellulitis
- Suspicion of necrotizing infection
- Presence of gas in tissues
- Compartment syndrome
For abscesses, incision and drainage is the primary treatment 1, 5
For necrotizing infections, aggressive and early surgical debridement is essential 1, 2
Special Considerations
For diabetic patients with lower extremity infections, evaluate for underlying osteomyelitis and consider more aggressive management 1
For recurrent infections, consider underlying conditions such as foreign bodies, chronic wounds, or immunosuppression 1, 6
For infections associated with injection drug use, maintain a high index of suspicion for necrotizing infection even when presenting as a simple abscess 6
Consider decolonization regimens for patients with recurrent staphylococcal infections 1