Surgical site infection incidence and surgical antibiotic prophylaxis in the ICU patient: a multicenter observational study.

BACKGROUND: Surgical site infection (SSI) is a major cause of postoperative morbidity. Surgical antibiotic prophylaxis (SAP), defined as the pre-incision administration of an antimicrobial agent targeting likely organisms in clean or clean-contaminated procedures without active infection at the operative site, is a cornerstone of prevention in surgery. However, critically ill patients represent a distinct population with profound susceptibility to infection. Data on SSI incidence and SAP practices in patients undergoing surgery during an intensive care unit (ICU) stay remain scarce. METHODS: Retrospective multicenter cohort study in five French ICUs (March 2022-March 2023). Adult patients (≥18 years) with an ICU stay ≥ 48 h who underwent surgery during their ICU stay were included. Primary outcome was SSI incidence after surgery. Generalized estimating equations (GEE) with a prespecified adjustment set were used to estimate the adjusted association between antimicrobial spectrum and SSI, accounting for clustering within centers. RESULTS: 338 patients were included (median age 56 years, IQR 35 - 67; 72% male). Overall SSI incidence was 21%. Procedures with suspected infection present at time of surgery (PATOS) (n = 52, 15%) had an SSI incidence of 37%, against 18% in PATOS-negative patients. In the primary adjusted GEE analysis, broad-spectrum vs. narrow-spectrum antimicrobials (OR 3.06; 95%CI 1.63-5.76; P < 0.001) and no antimicrobial vs. narrow-spectrum antimicrobials (OR 2.49; 95%CI 1.01-6.15; P = 0.048) were independently associated with SSI. Stratified analysis showed that antimicrobial spectrum also had significant effect on SSI risk on PATOS-positive and trauma patients. SSI was associated with prolonged ICU/hospital length of stay, increased organ support use, and worse outcomes at day 28 and day 90. CONCLUSIONS: SSI affects more than one in five critically ill patients. After adjustment for prespecified confounders, the association with broad-spectrum therapy likely reflected confounding by indication, whereas the absence of any antimicrobial coverage was independently associated with increased SSI risk. Conventional SAP guidelines derived from non-ICU populations may not apply to critically ill patients. ICU-specific prophylactic strategies, improved coordination between ICU and operating room teams, and prospective studies are needed to enhance SSI prevention in this high-risk population.