What is the appropriate management for a patient presenting with lower limb pain and high fever, potentially indicating a severe infection?

Management of Lower Limb Pain with High Fever

A patient presenting with lower limb pain and high fever requires immediate assessment for severe infection, particularly cellulitis or diabetic foot infection if diabetic, with urgent hospitalization and empiric broad-spectrum antibiotics if systemic signs are present, while simultaneously evaluating for limb-threatening conditions that may require emergency surgical intervention. 1

Immediate Assessment and Risk Stratification

Critical Red Flags Requiring Urgent Action

The presence of high fever with lower limb pain demands immediate evaluation for potentially limb-threatening or life-threatening infection. You must urgently assess for signs of severe infection including: 2

• Systemic inflammatory response (fever >38°C, tachycardia >90 bpm, hypotension) 1
• Rapidly progressing erythema or infection 2
• Gas in deeper tissues (crepitus) or necrotizing fasciitis 2
• Extensive necrosis, gangrene, or bullae (especially hemorrhagic) 2
• Pain out of proportion to clinical findings 2
• New onset wound anesthesia or loss of neurologic function 2
• Critical limb ischemia 2

Important caveat: The absence of fever or leukocytosis should NOT dissuade you from considering severe infection—diabetic patients and elderly may not mount typical inflammatory responses. 2, 1 Worsened glycemic control may be the only systemic evidence of serious infection in diabetic patients. 2

Diagnostic Approach

Obtain Cultures BEFORE Antibiotics (But Don't Delay Treatment)

Blood cultures should be obtained before initiating antibiotics, but this should not delay antibiotic initiation. 1 Blood cultures are positive in 5-15% of cellulitis cases and guide subsequent therapy. 1

For any visible wound or ulcer: 2

• Cleanse and debride the lesion first
• Obtain deep tissue specimens by curettage or biopsy from the debrided base (NOT superficial swabs of undebrided wounds) 2
• Send for both aerobic and anaerobic cultures 2

Imaging Considerations

• Plain radiographs are appropriate but secondary to immediate antimicrobial therapy in obvious cellulitis 1
• Consider advanced imaging (CT, MRI) if deep abscess, osteomyelitis, or necrotizing infection suspected 2

Critical Differential Diagnoses to Exclude

Before assuming infectious cellulitis, you must rule out: 1

• Deep venous thrombosis (assess for unilateral swelling, calf tenderness, risk factors) 1
• Charcot neuro-osteoarthropathy in diabetic patients (presents with unilateral red, warm, swollen foot—requires immediate immobilization, NOT antibiotics) 1
• Venous eczema (non-infectious red leg)—the most common misdiagnosis leading to unnecessary antibiotics 1

Immediate Management Algorithm

Hospitalization Criteria

Admit immediately if ANY of the following: 2, 1

• Systemic toxicity (fever, tachycardia, hypotension) 1
• Rapidly expanding erythema suggesting aggressive infection 1
• Evidence of deep space infection or abscess 2
• Metabolic instability 2
• Immunocompromised or diabetic patients (lower threshold for admission) 1
• Any signs from the limb-threatening infection table above 2

Empiric Antibiotic Therapy

For moderate to severe cellulitis with expanding erythema, initiate IV antibiotics immediately: 1

• Amoxicillin-clavulanic acid OR
• Cefazolin 1

For suspected methicillin-resistant staphylococci or severe infection, consider vancomycin. 3 Vancomycin is indicated for serious infections when methicillin-resistant organisms are suspected, but therapy should be adjusted once susceptibility data are available. 3

Do NOT delay antibiotics while waiting for imaging results—expanding cellulitis requires immediate treatment to prevent systemic sepsis and tissue necrosis. 1

Urgent Surgical Consultation

Request urgent surgical consultation (within 24 hours) for: 2

• Any evidence of gas in tissues, abscess, or necrotizing fasciitis (requires immediate surgical intervention) 2
• Wounds with substantial nonviable tissue requiring debridement 2
• Deep-space infection or unexplained persistent pain/tenderness 2
• Severe infection in diabetic patients 2

Prompt surgical debridement may decrease the likelihood that extensive amputation is needed. 2 Progressive abscess development, especially with ischemia, can rapidly lead to irreparable tissue damage. 2

Vascular Assessment

If the limb appears ischemic, refer immediately to vascular surgery. 2 For severely infected ischemic feet, revascularization should be performed early rather than delaying for prolonged antibiotic therapy. 2 However, careful debridement of necrotic infected material should not be delayed while awaiting revascularization. 2

Common Pitfalls to Avoid

• Do NOT assume absence of fever rules out serious infection in diabetic or elderly patients 1
• Do NOT prescribe antibiotics for venous eczema—this is the most common error leading to antibiotic resistance 1
• Do NOT delay surgical consultation when deep infection or systemic signs are present 2
• Do NOT use superficial wound swabs for culture—they provide inaccurate results 2