What is the first line of defense for wound prophylaxis?

First Line of Defense for Wound Prophylaxis

The first line of defense for wound prophylaxis is proper surgical technique including meticulous wound irrigation, debridement of devitalized tissue, and aseptic technique—antibiotics are an adjunct to, not a substitute for, these fundamental wound care principles. 1, 2

Foundational Wound Care Principles

• Mechanical wound preparation is paramount: Thorough irrigation removes foreign bodies and pathogens, while surgical debridement reduces bacterial load by removing necrotic tissue 1, 2
• Irrigation under high pressure should be avoided as it may drive bacteria deeper into tissue layers 1
• Prophylactic antibiotics are not a substitute for proper aseptic technique but rather an additional measure to decrease infection risk 1

When Antibiotics Become Part of the Defense Strategy

Timing is Critical

• Antibiotic administration must occur within 60 minutes before incision to ensure adequate tissue levels at the time of initial surgical exposure 1
• The first dose should preferably be given within 30 minutes before incision 3
• For trauma patients where pre-contamination dosing is impossible, simultaneous IV push and IM injection provides the fastest wound fluid concentrations 4

Clean Procedures (Class I Wounds)

• Prophylaxis is optional for most clean procedures but indicated when infection would be devastating (prosthetic implants, open-heart surgery) 1, 5
• Single-dose cefazolin significantly reduces infection rates: 3.6% versus 8.3% with placebo in closed fractures 1
• Cefazolin 1-2 grams IV is the standard agent for most clean procedures 5, 3
• Duration should not exceed 24 hours postoperatively for most procedures 1

Clean-Contaminated Procedures (Class II Wounds)

• Prophylactic antibiotics are uniformly recommended 3, 6
• For procedures requiring anaerobic coverage (gastrointestinal surgery), cefoxitin or combination therapy is warranted 6

Contaminated and Dirty Wounds (Class III and IV)

• These require therapeutic antibiotics, not prophylaxis 1
• Open fractures: Start antibiotics immediately and continue for 3 days (type I/II) or 5 days (type III), combined with antibiotic-impregnated PMMA beads 1

High-Risk Wound Scenarios Requiring Prophylaxis

Hand Wounds

• Amoxicillin-clavulanate 875/125 mg twice daily for 3-5 days is first-line for high-risk hand wounds 7
• Indications include: immunocompromised patients, wounds with edema, moderate-to-severe injuries, and injuries penetrating periosteum or joint capsule 7
• Alternative regimens: doxycycline 100 mg twice daily or clindamycin 300 mg three times daily 7

Bite Wounds

• Prophylaxis is indicated for hand bites, deep wounds, and wounds near critical areas (face, genitals, joints) 1
• Amoxicillin-clavulanate is preferred due to coverage of Pasteurella, Streptococcus, Staphylococcus, and anaerobes 1, 7
• Duration: 3-5 days for fresh wounds 1
• Do not give antibiotics if presentation is ≥24 hours post-bite without signs of infection 1

Gunshot Wounds

• Low-velocity: Controversial benefit; some evidence shows no difference in infection rates with or without antibiotics 1
• High-velocity: Treat with 48-72 hours of antibiotics (first-generation cephalosporin ± aminoglycoside) 1
• Add penicillin for gross contamination to cover Clostridium species 1

Common Pitfalls to Avoid

• Never use antibiotics as a substitute for proper wound cleaning and debridement—this is the most critical error 7, 2
• Avoid extending prophylaxis beyond recommended durations (increases resistance and adverse events without benefit) 1, 7
• Do not confuse prophylaxis (clean/clean-contaminated wounds) with therapeutic antibiotics (contaminated/dirty wounds) 1
• Failing to redose antibiotics intraoperatively for prolonged procedures (>2 hours): redose at 1-2 half-lives of the antibiotic 1, 3
• Using plastic adhesive drapes—these have no evidence of benefit in reducing surgical site infections 1

Adjunctive Measures That Enhance Defense

• Maintain intraoperative normothermia: Active warming devices reduce SSI rates 1
• Triclosan-coated sutures significantly reduce SSI compared to non-coated sutures 1
• Wound protector devices (especially dual-ring) reduce incisional SSI 1
• Negative-pressure wound therapy may be effective in high-risk patients 1
• Delayed primary closure should be considered for contaminated abdominal surgeries in high-risk patients 1