PSHP 2026 Residency Conference

Purpose: Ideal timing of preoperative antibiotic administration in relation to incision time remains unclear. This study aims to evaluate optimal timing of preoperative antibiotic administration to mitigate the risk of surgical site infection (SSI).


Methods: This study was a retrospective, case-control trial evaluating 993 adult patients admitted to St. Luke’s University Health Network for a surgical procedure between January 2022 and December 2024. Patients were included at a 1:4 case-to-control, with cases defined as patients who developed a SSI, and controls defined as patients without subsequent SSI. Patients were excluded if they did not receive preoperative antibiotics, received preoperative antibiotics > 120 minutes prior to incision, underwent more than one procedure during index hospitalization, or had a preexisting infection at time and anatomical site of index procedure. The primary outcome was SSI rate by preoperative antibiotic administration time. Secondary outcomes included admission for SSI, hospital length of stay, readmission for SSI, and mortality at 30 and 90 days post-operation. SSIs were categorized based on National Healthcare Safety Network (NHSN) definitions.


Results: Cefazolin was the most frequent preoperative antibiotic administered (863 of 993 cases). Preoperative administration time was evaluated at 15-minute intervals, with time 0 being start of procedure. The SSI rate when cefazolin was administered before or at 45 minutes prior to procedure was significantly lower than the SSI rate when cefazolin was administered beyond 45 minutes (18.5% vs 44.4%, P = 0.005). The majority of patients presenting with a SSI were admitted for inpatient management (67.6%). In the subgroup analysis, cefazolin was associated with a significantly lower rate of SSIs compared to clindamycin (P = 0.013).


Conclusion: Cefazolin should be administered within 45 minutes of procedure initiation to best mitigate the risk of SSIs. Cefazolin was associated with a lower rate of SSIs compared to clindamycin, supporting its use as the preoperative antibiotic of choice.


IRB approval: yes