What are the recommended antibiotics for skin and soft tissue infections?

Recommended Antibiotics for Skin and Soft Tissue Infections

For skin and soft tissue infections, first-line treatment should be with beta-lactam antibiotics targeting Staphylococcus aureus and Streptococcus species, with specific antibiotic selection based on infection severity and suspected pathogen resistance patterns. 1

Classification and Initial Treatment Approach

Uncomplicated/Non-purulent Infections (Cellulitis/Erysipelas)

• First-line:

  • Dicloxacillin 500 mg orally 4 times daily for 5-7 days 1
  • Cephalexin 500 mg orally 4 times daily for 5-7 days 1

• For penicillin-allergic patients:

  • Non-immediate hypersensitivity: Cephalexin 500 mg orally 4 times daily 1
  • Immediate hypersensitivity: Clindamycin 300-450 mg orally 3 times daily 1, 2
  • Alternative: Doxycycline 100 mg orally twice daily (not for children <8 years) 1

Purulent Infections (Abscesses)

• Primary treatment: Incision and drainage
• Adjunctive antibiotics (for extensive disease, systemic symptoms):
  • Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily 1
  • Doxycycline 100 mg twice daily 1

MRSA Infections

• Outpatient treatment:

  • Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily 1
  • Clindamycin 300-450 mg orally 3 times daily (if local resistance <10%) 1
  • Doxycycline/minocycline 100 mg twice daily 1

• Inpatient treatment:

  • Vancomycin 15 mg/kg IV every 12 hours 1
  • Linezolid 600 mg IV/orally every 12 hours 1, 3
  • Daptomycin 4 mg/kg IV every 24 hours 1
  • Ceftaroline 600 mg IV twice daily 1

Severe/Complicated Infections

Necrotizing Infections

• Empiric broad-spectrum coverage:
  • Vancomycin or linezolid PLUS piperacillin-tazobactam or a carbapenem 1, 4
  • For documented Group A Streptococcal infection: Penicillin plus clindamycin 1

Diabetic Foot Infections

• Mild to moderate:

  • Amoxicillin-clavulanate 875/125 mg orally twice daily 1, 2

• Severe:

  • Piperacillin-tazobactam 3.375 g IV every 6 hours 1, 4
  • Imipenem 500 mg IV every 6 hours or other carbapenem 1

Animal/Human Bites

• First-line:
  • Amoxicillin-clavulanate 875/125 mg orally twice daily 1
  • Ampicillin-sulbactam 1.5-3 g IV every 6 hours for severe infections 1

Special Considerations

Immunocompromised Patients

• Febrile neutropenia with SSTI:
  • Vancomycin plus antipseudomonal agent (cefepime, carbapenem, or piperacillin-tazobactam) 1
  • Duration: 7-14 days 1

Pediatric Dosing

• Cephalexin: 25 mg/kg/day in 4 divided doses orally 1
• Clindamycin: 10-20 mg/kg/day in 3 divided doses orally or 25-40 mg/kg/day in 3 divided doses IV 1, 2

Treatment Duration

• Uncomplicated infections: 5-7 days 1, 2
• Complicated infections: 7-14 days 1, 2
• Severe/necrotizing infections: 14-21 days or longer based on clinical response 1

Common Pitfalls to Avoid

1. Overuse of broad-spectrum antibiotics for uncomplicated infections - simple antibiotics like cephalexin are highly effective for most community-acquired SSTIs 5

2. Failure to consider MRSA in patients with risk factors or in areas with high MRSA prevalence

3. Inadequate surgical drainage of purulent collections - antibiotics alone are often insufficient for abscesses

4. Overlooking underlying conditions that may complicate treatment (diabetes, immunosuppression, vascular insufficiency)

5. Inappropriate antibiotic duration - shorter courses (5-7 days) are often sufficient for uncomplicated infections 2

Clinical evidence consistently shows that for uncomplicated skin infections, narrow-spectrum agents targeting the most common pathogens (Staphylococcus aureus and Streptococcus species) are highly effective, with cure rates exceeding 95% for agents like cephalexin 5, 6. Broader spectrum agents should be reserved for complicated infections or when specific risk factors for resistant organisms are present.