What are the recommended antibiotics for a local skin infection?

Recommended Antibiotics for Local Skin Infection

For uncomplicated local skin infections without purulent drainage (cellulitis), use oral antibiotics active against streptococci: cephalexin 500 mg every 6 hours, dicloxacillin 250-500 mg every 6 hours, or amoxicillin as first-line therapy. 1

Treatment Algorithm Based on Infection Type

For Non-Purulent Infections (Cellulitis)

Mild cases without systemic signs:

• First-line oral options: 1

  • Cephalexin 500 mg every 6 hours 2
  • Dicloxacillin 250-500 mg every 6 hours 3
  • Amoxicillin or penicillin VK 250-500 mg every 6 hours 1
  • Clindamycin 300-450 mg four times daily (if penicillin allergic) 1

• Duration: 5 days if clinical improvement occurs; extend if no improvement 1

When to add MRSA coverage:

• Add coverage if penetrating trauma, injection drug use, purulent drainage, evidence of MRSA elsewhere, or nasal MRSA colonization present 1
• MRSA-active oral options: 1
  • Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily 1
  • Doxycycline 100 mg twice daily 1
  • Clindamycin 300-450 mg four times daily 1

Critical caveat: Do not use trimethoprim-sulfamethoxazole or doxycycline as monotherapy for cellulitis without purulent drainage, as their activity against streptococci is uncertain; combine with a beta-lactam if MRSA coverage needed 1

For Purulent Infections (Abscesses, Furuncles)

Primary treatment is incision and drainage; antibiotics are adjunctive: 1

• Antibiotics indicated when: 1

  • Fever or systemic signs present
  • Multiple lesions
  • Immunocompromised host
  • Failed drainage alone

• Empiric antibiotic choices (MRSA-active): 1

  • Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily 1
  • Doxycycline 100 mg twice daily 1
  • Clindamycin 300-450 mg four times daily 1

• Duration: 5-10 days based on clinical response 1

For Superficial Localized Infections (Impetigo)

Topical therapy is first-line for limited lesions: 4

• Mupirocin 2% ointment applied 3 times daily for 7 days 4, 5, 6, 7
  • Highly effective against staphylococci and streptococci 5, 6
  • Clinical cure rates exceed 80% 5, 6
  • Equal efficacy to oral erythromycin for impetigo 7

Switch to systemic antibiotics when: 4

• Multiple widespread lesions present
• Deeper tissue involvement
• Systemic illness signs
• High-risk patient (diabetes, immunosuppression)
• High-risk location (face, hands, genitals)

Severe Infections Requiring Hospitalization

Indications for IV therapy: 1

• Systemic inflammatory response syndrome (SIRS)
• Hemodynamic instability
• Altered mental status
• Concern for necrotizing infection
• Severely immunocompromised

IV regimens: 1

• Vancomycin 15-20 mg/kg every 8-12 hours PLUS piperacillin-tazobactam or imipenem-meropenem for broad coverage 1
• Cefazolin 1 g every 8 hours for streptococcal/MSSA coverage 1

Recurrent Infections

Management approach: 1

• Drain and culture early 1
• Treat with 5-10 day course based on culture results 1
• Consider decolonization regimen: 1
  • Intranasal mupirocin twice daily for 5 days 1
  • Daily chlorhexidine washes 1
  • Daily decontamination of personal items (towels, sheets, clothes) 1

Key Clinical Pitfalls

Common errors to avoid:

• Blood cultures and tissue aspirates are NOT routinely needed for typical cellulitis 1
• MRSA is an uncommon cause of typical cellulitis; beta-lactam monotherapy succeeds in 96% of cases 1
• Do not use trimethoprim-sulfamethoxazole or doxycycline alone for non-purulent cellulitis due to uncertain streptococcal activity 1
• Topical antibiotics should only be used for limited, localized infections 4
• Incision and drainage is the primary treatment for abscesses; antibiotics are secondary 1