What antibiotic can be given to a patient with cellulitis who is allergic to penicillin, Keflex (Cephalexin), ciprofloxacin, doxycycline, levofloxacin, and clindamycin?

Antibiotic Options for Cellulitis with Multiple Allergies

For a patient with cellulitis allergic to penicillin, cephalexin, ciprofloxacin, doxycycline, levofloxacin, and clindamycin, vancomycin 15-20 mg/kg IV every 8-12 hours is the definitive first-line choice, requiring hospitalization for administration. 1

Intravenous Treatment Options

Given the extensive allergy profile eliminating all standard oral options, IV therapy becomes necessary:

Primary Recommendation

• Vancomycin 15-20 mg/kg IV every 8-12 hours provides A-I level evidence for complicated cellulitis and covers both streptococci and MRSA. 1, 2
• Treatment duration is 5 days if clinical improvement occurs, extending only if symptoms persist. 1

Alternative IV Options

• Linezolid 600 mg IV twice daily offers equivalent efficacy to vancomycin with A-I evidence and can be transitioned to oral formulation once improved. 1
• Daptomycin 4 mg/kg IV once daily provides A-I evidence for skin and soft tissue infections. 1
• Telavancin 10 mg/kg IV once daily is another alternative with documented efficacy. 1

Oral Transition Strategy

Once clinical improvement occurs (typically after 4-5 days of IV therapy):

• Linezolid 600 mg orally twice daily is the only viable oral option given this patient's allergy profile, providing coverage for both streptococci and MRSA. 2
• This allows completion of the 5-day course on an outpatient basis if the patient demonstrates clear clinical improvement. 1, 2

Critical Decision Points

When to Hospitalize

This patient requires hospitalization because: 1, 2

• All standard oral antibiotics are contraindicated by documented allergies
• IV vancomycin or alternatives necessitate inpatient administration initially
• Close monitoring for treatment response is essential given limited options

Severity Assessment

Evaluate for signs requiring broad-spectrum combination therapy: 1

• Systemic toxicity (fever, hypotension, tachycardia, altered mental status)
• Rapid progression or "wooden-hard" subcutaneous tissues suggesting necrotizing fasciitis
• If present, add piperacillin-tazobactam 3.375-4.5 g IV every 6 hours to vancomycin and obtain emergent surgical consultation

Essential Adjunctive Measures

• Elevate the affected extremity above heart level for at least 30 minutes three times daily to promote gravitational drainage and hasten recovery. 1, 2
• Examine interdigital toe spaces for tinea pedis, fissuring, or maceration and treat to reduce recurrence risk. 1
• Address predisposing conditions including venous insufficiency, lymphedema, and chronic edema. 1

Common Pitfalls to Avoid

• Do not attempt oral therapy initially with this allergy profile—the patient lacks safe oral options for monotherapy. 2
• Do not delay hospitalization hoping for outpatient management, as IV therapy is mandatory. 1
• Reassess at 48 hours to verify clinical response, as treatment failure with limited options requires immediate escalation. 1
• Consider allergy testing after acute infection resolves to potentially expand future antibiotic options, as some reported allergies may not represent true hypersensitivity. 2

Treatment Duration Algorithm

• Start vancomycin IV and assess at 48 hours for clinical improvement (reduced warmth, tenderness, erythema). 1
• If improving at day 4-5, transition to oral linezolid to complete 5-day total course. 1, 2
• If no improvement by day 5, extend treatment and reassess for complications or resistant organisms. 1
• For severe cellulitis with systemic toxicity, plan for 7-10 days minimum with combination therapy. 1