What are the recommended antibiotics for treating soft tissue infections?

Recommended Antibiotics for Soft Tissue Infections

For most uncomplicated soft tissue infections, first-line treatment is an antistaphylococcal beta-lactam such as dicloxacillin (500 mg four times daily) or cephalexin (500 mg four times daily) for methicillin-susceptible strains, while clindamycin (300-450 mg three times daily) or trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily) are recommended for suspected MRSA infections. 1

Classification and Initial Antibiotic Selection

Uncomplicated Skin and Soft Tissue Infections

• Cellulitis/Erysipelas (non-purulent):

  • First-line: Dicloxacillin 500 mg QID or Cephalexin 500 mg QID (7-10 days)
  • If penicillin-allergic: Clindamycin 300-450 mg TID
  • If MRSA suspected: Add coverage with TMP-SMX or Doxycycline

• Purulent infections (abscesses):

  • Incision and drainage is the primary treatment
  • Antibiotics may be unnecessary after adequate drainage 2
  • If antibiotics needed: TMP-SMX (1-2 DS tablets BID) or Doxycycline (100 mg BID)

Complicated Skin and Soft Tissue Infections

• Severe or necrotizing infections:

  • Broad-spectrum coverage: Piperacillin-tazobactam (3.375g IV q6h) 3, 4
  • Add Vancomycin (15-20 mg/kg IV q8-12h) for MRSA coverage
  • Consider adding Clindamycin (600-900 mg IV q8h) for toxin suppression in streptococcal infections

• Diabetic foot infections:

  • Amoxicillin-clavulanate 875/125 mg BID
  • Alternative: Clindamycin plus Ciprofloxacin or Levofloxacin

Specific Pathogens and Situations

MRSA Infections

• Oral options:

  • TMP-SMX (1-2 double-strength tablets BID)
  • Clindamycin (300-450 mg TID) if local resistance <10-15%
  • Doxycycline/Minocycline (100 mg BID)
  • Linezolid (600 mg BID) for severe infections

• IV options:

  • Vancomycin (30 mg/kg/day in 2 divided doses)
  • Linezolid (600 mg every 12h)
  • Daptomycin (4 mg/kg every 24h)

Animal/Human Bite Wounds

• Amoxicillin-clavulanate 875/125 mg BID (first choice) 1
• Alternative: Moxifloxacin 400 mg daily or Doxycycline 100 mg BID plus Metronidazole

Special Infections

• Cat Scratch Disease: Azithromycin 500 mg day 1, then 250 mg for 4 days 1
• Erysipeloid: Penicillin 500 mg QID or Amoxicillin 500 mg TID for 7-10 days 1
• Bubonic Plague: Streptomycin 15 mg/kg IM q12h or Doxycycline 100 mg BID 1
• Tularemia: Streptomycin/Gentamicin for severe cases; Tetracycline/Doxycycline for mild cases 1

Neutropenic Patients with Skin/Soft Tissue Infections

• Vancomycin plus antipseudomonal antibiotics (cefepime, carbapenem, or piperacillin-tazobactam) 1
• Treatment duration: 7-14 days

Duration of Therapy

• Uncomplicated infections: 5-10 days
• Complicated infections: 7-14 days
• Implant-related infections: 6-12 weeks (depending on implant retention) 5

Common Pitfalls to Avoid

1. Failure to drain abscesses: Surgical drainage is the primary treatment for abscesses; antibiotics alone are often insufficient
2. Overuse of broad-spectrum antibiotics: Simple infections often respond well to narrow-spectrum agents 6
3. Inadequate coverage for suspected MRSA: Consider local prevalence when selecting empiric therapy
4. Delayed surgical intervention for necrotizing infections: Early debridement is critical
5. Inappropriate duration: Avoid unnecessarily prolonged courses of antibiotics
6. Starting rifampicin too early in implant-related infections: Should be delayed until bacterial load is reduced and wounds are dry 5

Special Considerations

• For severe infections with systemic symptoms, rapidly spreading infection, or deep tissue involvement, consider hospitalization for IV antibiotics
• Tetanus prophylaxis should be considered when indicated
• Regular reassessment of response to therapy is essential to guide potential changes in antibiotic regimen