What is the best antibiotic for skin infections?

Best Antibiotic for Skin Infections

For most uncomplicated skin infections, dicloxacillin, cephalexin, or clindamycin are the preferred first-line antibiotics, with specific choices depending on the suspected pathogen and severity of infection. 1

Antibiotic Selection Based on Infection Type

Impetigo

• First-line options:
  • Dicloxacillin: 250 mg 4 times daily (adults) 1
  • Cephalexin: 250-500 mg 4 times daily (adults); 25-50 mg/kg/day in 3-4 divided doses (children) 1
  • Mupirocin ointment: Apply to lesions twice daily (for limited number of lesions) 1
• Alternative options:
  • Clindamycin: 300-400 mg 3 times daily (adults); 20 mg/kg/day in 3 divided doses (children) 1
  • Amoxicillin-clavulanate: 875/125 mg twice daily (adults); 25 mg/kg/day of amoxicillin component in 2 divided doses (children) 1

Cellulitis (Non-purulent)

• Mild cases (no systemic signs): Antimicrobial agent active against streptococci 1
  • Penicillin: 250-500 mg every 6 hours orally 1
  • Cephalexin: 500 mg 4 times daily 1
• Moderate cases (with systemic signs): Consider coverage for both streptococci and MSSA 1
  • Cefazolin: 1 g every 8 hours IV 1
  • Clindamycin: 600 mg every 8 hours IV 1
• Severe cases or MRSA risk factors: Coverage for both MRSA and streptococci 1
  • Vancomycin: 30 mg/kg/day in 2 divided doses IV 1
  • Linezolid: 600 mg every 12 hours IV or orally 1, 2

Purulent Skin Infections (Abscesses)

• Primary treatment: Incision and drainage 1
• Adjunctive antibiotics for moderate-severe cases:
  • Trimethoprim-sulfamethoxazole: 1-2 double-strength tablets twice daily 1
  • Doxycycline: 100 mg twice daily (not for children <8 years) 1
  • Clindamycin: 300-450 mg 3 times daily 1

MRSA Skin Infections

• Outpatient treatment:
  • Clindamycin: 300-450 mg 3 times daily orally 1
  • Trimethoprim-sulfamethoxazole: 1-2 double-strength tablets twice daily 1
  • Doxycycline: 100 mg twice daily (not for children <8 years) 1
  • Linezolid: 600 mg twice daily 1, 2
• Inpatient treatment:
  • Vancomycin: 30 mg/kg/day in 2 divided doses IV 1
  • Linezolid: 600 mg every 12 hours IV or orally 1, 2
  • Daptomycin: 4 mg/kg every 24 hours IV 1
  • Ceftaroline: 600 mg twice daily IV 1

Special Considerations

Animal or Human Bites

• First-line: Amoxicillin-clavulanate: 875/125 mg twice daily orally 1
• Alternatives:
  • Ampicillin-sulbactam: 1.5-3.0 g every 6 hours IV 1
  • Doxycycline: 100 mg twice daily (excellent activity against Pasteurella multocida) 1
  • For human bites: Consider broader coverage including anaerobes 1

Necrotizing Infections

• Immediate surgical debridement is crucial 1
• Empiric broad-spectrum coverage:
  • Vancomycin plus piperacillin-tazobactam or a carbapenem 1
• For confirmed streptococcal infection:
  • Penicillin plus clindamycin: 2-4 million units every 4-6 hours IV plus 600-900 mg every 8 hours IV 1
• For confirmed staphylococcal infection:
  • Nafcillin: 1-2 g every 4 hours IV 1
  • For MRSA: Vancomycin: 30 mg/kg/day in 2 divided doses IV 1

Duration of Therapy

• For most uncomplicated skin infections: 5-7 days 1
• For complicated infections: 7-14 days, based on clinical response 1
• For necrotizing infections: 2-3 weeks 1

Clinical Pearls and Pitfalls

• Always consider local resistance patterns when selecting empiric therapy 1
• Incision and drainage alone may be sufficient for simple abscesses without antibiotics 1
• Topical antibiotics (mupirocin, retapamulin) are highly effective for limited impetigo lesions and may help prevent antibiotic resistance 3
• Linezolid has equivalent oral and IV bioavailability, making it excellent for transitioning from IV to oral therapy 2, 4
• Cephalexin twice daily dosing has shown similar efficacy to four-times-daily regimens in some studies, potentially improving compliance 5
• Elevation of affected areas and treatment of predisposing factors (edema, underlying skin disorders) are important adjunctive measures 1
• For recurrent MRSA infections, consider decolonization with intranasal mupirocin, daily chlorhexidine washes, and decontamination of personal items 1