Cefazolin versus Vancomycin and Ceftazidim for Prevention of Sternal Wound Infection after Cardiac Surgery

Background: Surgical site infection (SSI) after cardiac surgery performed via a mid-sternotomy incision is a dreadful complication associated with high mortality, morbidity, and substantial cost. Therefore, antibiotic prophylaxis is uniformly administered. Data regarding the optimal regimen in Israeli population is scarce.

Aim: To compare two prophylactic regimens – a 1^st generation cephalosporin – Cefazolin (Cef) versus a combination of Vancomycin and a 3^d generation cephalosporin - Cetazidim (VC).

Methods: We reviewed data that were prospectively entered into our database on 1899 patients undergoing cardiac surgery via mid-sternotomy between 2008 and 2015. Using the Society of Thoracic Surgeons definitions, the data collected included demographics, risk factors, procedural details and outcomes. 908 patient receiving Cef were compared with 727 patients receiving VC. 264 patients received a variety of other combinations. We performed univariable and multivariable analyses to identify predictors of SSI.

Results: SSI was observed in 24 (1.3%) patients (deep – 17 [0.9%], superficial – 7 [0.4%]). The most common pathogen was methicillin-sensitive staphylococcus aureus (MSSA). The rate of SSI was higher in patients receiving VC compared to Cef (2.1%, vs. 1.0%, p=0.04), correlating with their higher risk profile. Predictors of SSI in a univariate analysis included female gender, BMI, length of surgery, cardiopulmonary bypass time and blood transfusions. In a multivariate analysis female gender (OR 2) and blood transfusions(OR 2.6) remained independent predictors of SSI. Thirty-day mortality of patients with SSI was similar to that of controls (0% vs.3.9%, p=0.32). SSI was associated with a significant increase in postoperative renal failure, ICU and hospital length of stay.

Conclusions: Our data suggest that SSI after cardiac surgery is related to patient and procedural factors rather than the type of antibiotics. Cef should be the prophylactic antibiotic of choice in most cases. Wide-spectrum coverage should be used in selected cases only.