What is the treatment for staphylococcal (Staph) skin infections?

Treatment of Staphylococcal Skin Infections

For typical uncomplicated staphylococcal skin infections without purulent drainage, beta-lactam monotherapy with oral dicloxacillin, cephalexin, or amoxicillin for 5 days is the standard of care, achieving 96% success rates. 1

Initial Assessment: Purulent vs. Non-Purulent

The single most critical decision is determining whether the infection is purulent or non-purulent, as this fundamentally changes management:

• Purulent infections (abscesses, furuncles, carbuncles with visible pus) require incision and drainage as primary treatment—antibiotics alone are insufficient 2
• Non-purulent infections (cellulitis, erysipelas without drainage) are treated with antibiotics as primary therapy 1

Antibiotic Selection Algorithm

For Non-Purulent Infections (Typical Cellulitis)

First-line oral agents (choose one): 1

• Dicloxacillin 250-500 mg every 6 hours
• Cephalexin 500 mg four times daily
• Amoxicillin (standard dosing)
• Penicillin V 250-500 mg four times daily

Treatment duration: Exactly 5 days if clinical improvement occurs; extend only if symptoms have not improved. 1 This represents a major shift from traditional 7-14 day courses, which are no longer necessary for uncomplicated cases. 1

MRSA coverage is NOT routinely needed for typical non-purulent cellulitis, even in hospitals with high MRSA prevalence, because MRSA is an uncommon cause of this presentation. 1

When to Add MRSA Coverage

Add MRSA-active antibiotics ONLY when specific risk factors are present: 1

• Penetrating trauma or injection drug use
• Purulent drainage or exudate
• Known MRSA colonization or prior MRSA infection
• Systemic inflammatory response syndrome (SIRS)
• Failure of beta-lactam therapy after 48-72 hours

MRSA-active oral regimens (choose one): 1, 2

• Clindamycin 300-450 mg every 6 hours (single agent covering both streptococci and MRSA—ideal when dual coverage needed, but only if local resistance <10%) 1, 2
• TMP-SMX (1-2 DS tablets twice daily) PLUS a beta-lactam (cephalexin, amoxicillin, or penicillin) 2
• Doxycycline 100 mg twice daily PLUS a beta-lactam 1, 2

Critical pitfall: Never use doxycycline or TMP-SMX as monotherapy for cellulitis—their activity against beta-hemolytic streptococci is unreliable. 1, 2

Intravenous Therapy for Severe Infections

Indications for hospitalization and IV antibiotics: 1

• Systemic toxicity (fever, hypotension, tachycardia, confusion)
• Rapid progression or suspected necrotizing fasciitis
• Severe immunocompromise or neutropenia
• Failure of oral therapy

For complicated infections requiring IV therapy: 1, 3, 4

• Vancomycin 15-20 mg/kg IV every 8-12 hours (first-line, A-I evidence) 1, 3
• Alternatives: Linezolid 600 mg IV twice daily, daptomycin 4 mg/kg IV once daily, or clindamycin 600 mg IV every 8 hours (if local resistance <10%) 1, 4

For severe infections with systemic toxicity or suspected necrotizing fasciitis, mandatory broad-spectrum combination therapy: 1

• Vancomycin or linezolid PLUS piperacillin-tazobactam 3.375-4.5 g IV every 6 hours
• Alternative: Vancomycin PLUS a carbapenem or ceftriaxone plus metronidazole

Treatment duration for severe infections: 7-14 days guided by clinical response. 1

Special Situations

Furuncles and Abscesses

• Small furuncles: Moist heat to promote drainage; systemic antibiotics usually unnecessary unless extensive surrounding cellulitis or fever 5
• Larger furuncles and all carbuncles: Incision and drainage required 5
• Recurrent furunculosis: Mupirocin ointment in anterior nares twice daily for first 5 days each month (reduces recurrences by ~50%), or clindamycin 150 mg daily for 3 months (reduces recurrences by ~80%) 5

Bite-Associated Cellulitis

• Amoxicillin-clavulanate 875/125 mg twice daily provides single-agent coverage for polymicrobial oral flora from animal or human bites 1

Penicillin/Cephalosporin Allergy

• Clindamycin 300-450 mg every 6 hours (covers both streptococci and MRSA) 1
• Levofloxacin 500 mg daily (reserve for beta-lactam allergies; lacks reliable MRSA coverage) 1
• Vancomycin IV for hospitalized patients 1

Critical Adjunctive Measures

These non-antibiotic interventions are often neglected but accelerate healing: 1

• Elevation of affected extremity above heart level for at least 30 minutes three times daily (promotes gravity drainage) 1
• Examine and treat interdigital toe spaces for tinea pedis, fissuring, or maceration (eradicates colonization, reduces recurrence) 1
• Address predisposing conditions: venous insufficiency, lymphedema, chronic edema 1

Common Pitfalls to Avoid

• Do not reflexively add MRSA coverage for typical non-purulent cellulitis without specific risk factors—this represents overtreatment and drives resistance 1
• Do not continue ineffective antibiotics beyond 48 hours—progression despite appropriate therapy indicates resistant organisms or deeper infection 1
• Do not delay surgical consultation if any signs of necrotizing infection (severe pain out of proportion, skin anesthesia, rapid progression, gas in tissue, bullous changes) 1
• Do not use antibiotics alone for abscesses—incision and drainage is the cornerstone of treatment 2
• Never use rifampin as monotherapy for skin infections due to rapid resistance development 2

Reassessment and Treatment Failure

Mandatory reassessment within 24-48 hours to verify clinical response. 1 If spreading despite appropriate antibiotics:

1. Evaluate for necrotizing fasciitis (emergent surgical consultation if suspected) 1
2. Reassess for MRSA risk factors 1
3. Consider misdiagnosis (abscess requiring drainage, septic bursitis, osteomyelitis) 1
4. Switch to vancomycin or linezolid if MRSA suspected 1