Recommended Antibiotics for Skin and Soft Tissue Infections
For uncomplicated skin and soft tissue infections, first-line therapy includes dicloxacillin, cephalexin, clindamycin, or amoxicillin-clavulanate, with antibiotic selection based on suspected pathogens and local resistance patterns. 1
Empiric Antibiotic Selection by Infection Type
Impetigo
- Dicloxacillin 250 mg four times daily (adults) or 12 mg/kg/day in 4 divided doses (children) 1
- Cephalexin 250 mg four times daily (adults) or 25 mg/kg/day in 4 divided doses (children) 1
- Erythromycin 250 mg four times daily (adults) or 40 mg/kg/day in 4 divided doses (children), though some strains of S. aureus and S. pyogenes may be resistant 1
- Mupirocin ointment applied three times daily for limited lesions 1
Methicillin-Susceptible S. aureus (MSSA) Infections
- Nafcillin or oxacillin 1-2 g every 4 hours IV (parenteral drug of choice) 1
- Dicloxacillin 500 mg four times daily PO (oral agent of choice) 1
- Cephalexin 500 mg four times daily PO (alternative for penicillin-allergic patients without immediate hypersensitivity) 1, 2
- Clindamycin 300-450 mg three times daily PO or 600 mg every 8 hours IV 1
Methicillin-Resistant S. aureus (MRSA) Infections
Oral options:
IV options:
Animal or Human Bites
- Amoxicillin-clavulanate 875/125 mg twice daily PO (drug of choice for animal bites) 1, 4
- Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours IV 1
- For penicillin allergic patients: doxycycline 100 mg twice daily PO or clindamycin plus TMP-SMX 1
Diabetic Foot Infections
- Mild infections: dicloxacillin, clindamycin, cephalexin, levofloxacin, or amoxicillin-clavulanate 1
- Moderate to severe infections: broader coverage may be needed with agents like ertapenem, piperacillin-tazobactam, or combination therapy 1
Duration of Therapy
- For most uncomplicated skin infections: 7-10 days 4, 5
- For streptococcal infections: minimum 10 days to prevent rheumatic fever 1
- For more severe infections: 7-14 days, individualized based on clinical response 1
Special Considerations
MRSA Risk Factors
- Previous MRSA infection or colonization 6
- Recent hospitalization or healthcare exposure 1
- High local prevalence of community-acquired MRSA 1
- Failed initial beta-lactam therapy 3
Incision and Drainage
- For abscesses, incision and drainage is essential and may be sufficient without antibiotics in some cases 7
- Antibiotics should be added for abscesses with surrounding cellulitis, systemic symptoms, or in immunocompromised hosts 1, 7
Antibiotic Resistance Concerns
- Local resistance patterns should guide empiric therapy 8
- Culture and sensitivity testing is recommended for:
Dosing for Common Oral Antibiotics
- Cephalexin: 500 mg four times daily for adults; 25-50 mg/kg/day in divided doses for children 4, 2
- Dicloxacillin: 500 mg four times daily for adults 1
- Clindamycin: 300-450 mg three times daily for adults 1
- TMP-SMX: 1-2 double-strength tablets twice daily for adults 1
- Doxycycline: 100 mg twice daily for adults (not recommended for children under 8 years) 1
Pitfalls to Avoid
- Using beta-lactams empirically in areas with high MRSA prevalence without obtaining cultures 6
- Failing to consider Pasteurella multocida in animal bite infections (poor response to cephalexin alone) 4
- Overlooking the need for anaerobic coverage in human bites, diabetic foot infections, and perianal abscesses 1
- Continuing ineffective antibiotics without obtaining cultures in non-responding infections 8
- Using antibiotics alone without adequate drainage for abscesses 7