Best Antibiotic for Deep Lacerations
For deep lacerations requiring antibiotic prophylaxis, amoxicillin-clavulanate 875/125 mg twice daily is the first-line choice, providing coverage against the polymicrobial flora typically contaminating traumatic wounds. 1
When to Use Antibiotics
Preemptive antibiotic therapy for 3-5 days is recommended for deep lacerations when patients meet any of these criteria 1:
- Immunocompromised status
- Asplenia
- Advanced liver disease
- Preexisting or resultant edema of the affected area
- Moderate to severe injuries, especially to the hand or face
- Injuries that may have penetrated the periosteum or joint capsule
First-Line Antibiotic Choice
Amoxicillin-clavulanate is the preferred agent because it provides coverage against both aerobic and anaerobic bacteria commonly found in contaminated wounds 1:
- Adults: 875/125 mg twice daily orally 1
- Children: 25 mg/kg/day of the amoxicillin component in 2 divided doses 1
- Duration: 3-5 days for prophylaxis 1
This combination covers Staphylococcus aureus, streptococci, and anaerobes that typically contaminate traumatic wounds 1.
Alternative Oral Agents
If amoxicillin-clavulanate cannot be used, consider 1:
- Cephalexin 500 mg four times daily (covers gram-positive organisms but misses anaerobes) 1
- Clindamycin 300-450 mg three times daily (excellent for staphylococci, streptococci, and anaerobes) 1, 2
- Doxycycline 100 mg twice daily (avoid in children <8 years) 1
Intravenous Options for Severe Injuries
For deep lacerations requiring hospitalization or IV therapy 1:
- Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours IV 1
- Piperacillin-tazobactam 3.37 g every 6-8 hours IV 1
- Cefazolin 1 g every 8 hours IV (for MSSA coverage, but add anaerobic coverage) 1
Special Considerations for Bite Wounds
If the laceration is from an animal or human bite, amoxicillin-clavulanate remains the drug of choice because these wounds contain an average of 5 different aerobic and anaerobic bacteria, including Pasteurella species (in animal bites) and Eikenella corrodens (in human bites) 1.
Avoid these antibiotics for bite wounds as they have poor activity against key pathogens 1:
- First-generation cephalosporins alone (miss Pasteurella)
- Clindamycin alone (misses Pasteurella and Eikenella)
- Macrolides like erythromycin
Critical Pitfalls to Avoid
Do not close infected wounds or deep contaminated lacerations primarily (except facial wounds managed by specialists with copious irrigation and antibiotics) 1. Wounds should be cleansed with sterile normal saline, and approximation by Steri-Strips with delayed closure is preferred 1.
Do not forget tetanus prophylaxis: administer tetanus toxoid to patients without vaccination within 10 years, preferring Tdap over Td if not previously given 1.
Start antibiotics promptly: delay >3 hours increases infection risk in contaminated wounds 1.