Surgical Infection Prophylaxis — Modern Antimicrobial Strategies

Surgical antimicrobial prophylaxis (SAP) is the brief perioperative administration of antibiotics intended to reduce the risk of surgical site infection (SSI) by establishing bactericidal serum and tissue drug concentrations before potential bacterial contamination occurs. It targets the most likely pathogens based on procedure type and patient factors, distinct from therapeutic antibiotic treatment of established infection.

Procedure-specific recommendations follow ASHP/IDSA/SIS/SHEA guidelines: cefazolin remains the preferred agent for most clean and clean-contaminated procedures targeting skin flora (Staphylococcus aureus, coagulase-negative staphylococci) and gram-negative bacilli. Colorectal surgery requires additional anaerobic coverage with metronidazole or use of cefoxitin, ertapenem, or ampicillin-sulbactam. Patients with documented severe beta-lactam allergy receive clindamycin plus gentamicin or fluoroquinolone alternatives.

Critical timing principles dictate first-dose administration within 60 minutes before surgical incision (120 minutes for vancomycin or fluoroquinolones requiring extended infusion), with weight-based dosing (cefazolin 2 g for adults, 3 g if >120 kg). Intraoperative redosing is required when surgical duration exceeds two half-lives of the drug or when blood loss exceeds 1500 mL. Postoperative continuation beyond 24 hours offers no additional benefit while increasing resistance, Clostridioides difficile infection, and adverse drug effects—a key antimicrobial stewardship principle.