What is the best course of treatment for a patient with a 3-day history of leg redness and inflammation, now with an open wound, difficulty walking, fatigue, hypotension, and taking amlodipine 5mg daily?

Immediate Hospitalization and Broad-Spectrum IV Antibiotics Required

This patient has severe cellulitis with systemic inflammatory response syndrome (SIRS) manifesting as hypotension (89/47 mmHg), tachycardia (implied by "vital signs"), and fatigue, requiring immediate hospital admission and empiric IV antibiotics covering both MRSA and polymicrobial/necrotizing infection. 1

Critical Assessment Points

Severity Classification:

• The presence of hypotension (89/47 mmHg) meets SIRS criteria and indicates severe infection requiring hospitalization 2, 1
• The open wound with surrounding erythema, inability to walk, and fatigue over 3 days with acute worsening suggests rapidly progressive infection 1
• Hypotension is an absolute indication for admission and represents hemodynamic instability 1

Warning Signs to Evaluate Immediately:

• Assess for severe pain out of proportion to examination, skin anesthesia, "wooden-hard" subcutaneous tissues, crepitus, bullae, or skin necrosis—any of these suggest necrotizing fasciitis requiring emergent surgical consultation 2, 1
• The open wound increases risk for deeper tissue involvement including fascia, tendon, muscle, or bone 1
• Probe the wound to assess depth and whether it extends to bone (probe-to-bone test) 2

Immediate Management Algorithm

Step 1: Stabilize and Admit

• Immediate hospitalization for IV fluid resuscitation to correct hypotension 2, 1
• Obtain blood cultures before antibiotics given systemic toxicity 2
• Obtain wound cultures from debrided tissue base (not swabs of surface) 2
• Plain radiographs of the leg to evaluate for gas in tissue or osteomyelitis 2

Step 2: Initiate Broad-Spectrum IV Antibiotics Within 1 Hour

For severe cellulitis with systemic toxicity and open wound, use combination therapy: 3

• Vancomycin 15-20 mg/kg IV every 8-12 hours (targeting MRSA and streptococci) 3
• PLUS Piperacillin-tazobactam 3.375-4.5 grams IV every 6 hours (covering polymicrobial infection including gram-negatives and anaerobes) 3

Alternative combinations if vancomycin unavailable: 3

• Linezolid 600 mg IV twice daily PLUS piperacillin-tazobactam 3
• Vancomycin PLUS a carbapenem (meropenem 1 g IV every 8 hours) 3

Step 3: Surgical Consultation

• Immediate surgical evaluation given open wound, systemic toxicity, and potential for deep tissue involvement 2, 1
• Surgical debridement may be necessary for source control, especially if necrotizing infection suspected 2

Step 4: Address Amlodipine-Related Edema

• Amlodipine causes pedal edema as a common adverse effect, which is a major predisposing factor for cellulitis 4, 5
• Consider switching to an ACE inhibitor or ARB once stabilized, as these reduce calcium channel blocker-induced edema 5
• Diuretics are ineffective for amlodipine-induced edema 5

Treatment Duration and Monitoring

Initial Phase:

• Continue IV antibiotics until clinical improvement evident (typically 48-72 hours): resolution of fever, hemodynamic stability, decreasing erythema 3
• Reassess daily for response to therapy 2

Total Duration:

• 7-14 days total for severe cellulitis with systemic toxicity, guided by clinical response 3
• Can transition to oral antibiotics once clinically improved (typically after 4-5 days IV therapy) 3

Oral Step-Down Options (once stable):

• Clindamycin 300-450 mg every 6 hours (if local MRSA resistance <10%) 3
• OR Linezolid 600 mg twice daily 3

Essential Adjunctive Measures

Immediate:

• Elevate the affected leg above heart level for at least 30 minutes three times daily to promote drainage 3
• Examine interdigital toe spaces for tinea pedis, fissuring, or maceration—treat if present to reduce recurrence risk 3

Once Acute Infection Resolves:

• Address chronic edema with compression therapy 4
• Optimize amlodipine management (reduce dose, switch medication, or add ACE inhibitor) 5
• Treat any venous insufficiency or lymphedema 3

Critical Pitfalls to Avoid

• Do not delay antibiotics: Severe cellulitis with hypotension requires antibiotics within 1 hour of recognition 3
• Do not use beta-lactam monotherapy: The open wound and systemic toxicity mandate MRSA coverage plus broad-spectrum coverage 3
• Do not miss necrotizing infection: Severe pain, rapid progression, or "wooden-hard" tissues require immediate surgical intervention 2, 1
• Do not overlook the amlodipine: Pedal edema from amlodipine creates a vicious cycle—edema predisposes to cellulitis, and cellulitis worsens edema 4, 5

Special Considerations

If Diabetic (not specified but consider):

• Diabetic foot infections require broader coverage and longer duration 2
• Assess for peripheral neuropathy and vascular disease 2
• Consider osteomyelitis if chronic wound or probes to bone 2

Follow-Up:

• Reevaluate within 24 hours to verify response 3
• If no improvement after 48-72 hours of appropriate IV therapy, obtain advanced imaging (MRI or CT) to evaluate for abscess, necrotizing infection, or osteomyelitis 1