The incidence of surgical site infection (SSI) after cardiac surgery depends on the definition used. A distinction is generally made between mediastinitis, as defined by the US Centers for Disease Control and Prevention (CDC), and superficial SSI. Our objective was to decipher these entities in terms of presentation and risk factors. We performed a 7-year single centre analysis of prospective surveillance of patients with cardiac surgery via median sternotomy. SSI was defined as the need for reoperation due to infection. Among 7170 patients, 292 (4.1%) developed SSI, including 145 CDC-defined mediastinitis (CDC-positive SSI, 2.0%) and 147 superficial SSI without associated bloodstream infection (CDC-negative SSI, 2.1%). Median time to reoperation for CDC-negative SSI was 18 days (interquartile range, 14-26) and 16 (interquartile range, 11-24) for CDC-positive SSI (p 0.02). Microorganisms associated with CDC-negative SSI were mainly skin commensals (62/147, 41%) or originated in the digestive tract (62/147, 42%); only six were due to Staphylococcus aureus (4%), while CDC-positive SSI were mostly due to S. aureus (52/145, 36%) and germs from the digestive tract (52/145, 36%). Risk factors for SSI were older age, obesity, chronic obstructive bronchopneumonia, diabetes mellitus, critical preoperative state, postoperative vasopressive support, transfusion or prolonged ventilation and coronary artery bypass grafting, especially if using both internal thoracic arteries in female patients. The number of internal thoracic arteries used and factors affecting wound healing were primarily associated with CDC-negative SSI, whereas comorbidities and perioperative complications were mainly associated with CDC-positive SSI. These 2 entities differed in time to revision surgery, bacteriology and risk factors, suggesting a differing pathophysiology.

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BackgroundSternal Wound Infection (SWI) is a severe complication after cardiac surgery. Debridement associated with primary closure using Redon drains (RD) is an effective treatment, but data on RD management and antibiotic treatment are scarce.MethodsWe performed a single-center analysis of consecutive patients who were re-operated for SWI between 01/2009 and 12/2012. All patients underwent a closed drainage with RD (CDRD). Patients with endocarditis or those who died within the first 45 days were excluded from management analysis. RD fluid was cultured twice weekly. Variables recorded were clinical and biological data at SWI diagnosis, severity of SWI based on criteria for mediastinitis as defined by the Centers for Disease Control (CDC), antibiotic therapy, RD management and patient’s outcome.Results160 patients developed SWI, 102 (64%) fulfilled CDC criteria (CDC+) and 58 (36%) did not (CDC- SWI). Initial antibiotic treatment and surgical management were similar in CDC+ and CDC- SWI. Patients with CDC+ SWI had a longer duration of antibiotic therapy and a mortality rate of 17% as compared to 3% in patients with CDC- SWI (p = 0.025). Rates of superinfection (10% and 9%) and need for second reoperation (12% and 17%) were similar. Failure (death or need for another reoperation) was associated with female gender, higher EuroScore for prediction of operative mortality, and stay in the ICU.ConclusionIn patients with SWI, initial one-stage surgical debridement with CDRD is associated with favorable outcomes. CDC+ and CDC- SWI received essentially the same management, but CDC+ SWI has a more severe outcome.