What is the best antibiotic for an infected wound?

Best Antibiotic for Infected Wounds

For most infected wounds, the best antibiotic is amoxicillin-clavulanic acid for mild infections, while severe infections require combination therapy with vancomycin or linezolid plus piperacillin-tazobactam or a carbapenem. 1

Assessment of Wound Severity

Wound infection severity determines antibiotic selection:

• Mild infection: <5 cm of erythema/induration, temperature <38.5°C, WBC <12,000/µL, pulse <100 beats/min
• Moderate-severe infection: >5 cm erythema, temperature >38.5°C, heart rate >110 beats/min, or systemic signs of infection

Antibiotic Selection Algorithm

Mild Infections

1. First-line: Amoxicillin-clavulanic acid 1
2. Alternatives:
   • Cloxacillin/dicloxacillin 1
   • Cephalexin 1
   • Clindamycin (good for anaerobes and most gram-positives) 1

Moderate to Severe Infections

1. First-line combination therapy:

   • Vancomycin or linezolid plus piperacillin-tazobactam 1
   • Vancomycin plus a carbapenem (imipenem, meropenem, ertapenem) 1
   • Ceftriaxone plus metronidazole (with or without vancomycin) 1

2. Single-drug regimens (for specific situations):

   • Ticarcillin-clavulanate (3.1g every 6h IV)
   • Piperacillin-tazobactam (3.375g every 6h or 4.5g every 8h IV)
   • Imipenem-cilastatin (500mg every 6h IV)
   • Meropenem (1g every 8h IV)
   • Ertapenem (1g every 24h IV) 1

Special Considerations

MRSA Coverage

Add vancomycin, linezolid, or daptomycin when:

• Prior history of MRSA infection
• High local prevalence of MRSA
• Clinically severe infection 1

Necrotizing Fasciitis

• Requires urgent surgical consultation 1
• Clindamycin plus piperacillin-tazobactam (with or without vancomycin) 1
• For documented group A streptococcal necrotizing fasciitis: penicillin plus clindamycin 1

Diabetic Foot Infections

• Uninfected wounds: no antibiotics 1
• Mild infections: dicloxacillin, clindamycin, cephalexin, amoxicillin-clavulanic acid 1
• Moderate-severe: levofloxacin, ceftriaxone, ampicillin-sulbactam, ertapenem 1

Animal/Human Bites

• Animal bites: Amoxicillin-clavulanic acid (oral) or ampicillin-sulbactam (IV) 1
• Human bites: Amoxicillin-clavulanic acid, ampicillin-sulbactam, or carbapenems 1

Route and Duration of Administration

Route

• Mild infections: Oral antibiotics
• Moderate-severe infections: Initial parenteral therapy, then switch to oral when patient improves clinically 1

Duration

• Mild soft tissue infections: 1-2 weeks
• Moderate-severe infections: 2-3 weeks 1
• Osteomyelitis: 6 weeks if bone cannot be completely resected 2

Important Caveats

1. Antibiotics alone are insufficient - proper wound debridement and drainage are essential components of treatment 1

2. Culture before antibiotics when possible:

   • Cleanse and debride the wound first
   • Obtain tissue specimen by scraping with sterile scalpel or biopsy from wound base
   • Avoid swabbing the wound surface 1

3. Do not treat clinically uninfected wounds with antibiotics 1

4. Tetanus prophylaxis should be administered to patients without vaccination within 10 years (Tdap preferred if not previously given) 1, 2

5. Switch from IV to oral therapy when the patient is systemically well and culture results are available 1

By following this evidence-based approach to antibiotic selection for infected wounds, you can optimize patient outcomes while minimizing unnecessary antibiotic use and resistance development.