Comparison of 48 h and 72 h of prophylactic antibiotic therapy in adult cardiac surgery: a randomized double blind controlled trial

To determine whether the duration of antibiotic prophylaxis influences the rate of surgical site infection in patients undergoing coronary bypass grafting or valve replacement. Adult patients undergoing elective coronary artery bypass grafting (CABG) and valve surgery were included in this randomized double blind study. Between April 2007 and April 2008, 235 patients were randomly assigned to one of two groups using random number table and sealed envelope technique. The groups received prophylactic antibiotic therapy for either 48 h (the 48 h group) or 72 h (the 72 h group). These patients were monitored for surgical site infection. The mean age was 52.94 +/- 16.30 and 55.27 +/- 16.63 years, respectively, in the two groups. The incidence of co-morbid conditions as well as operative conditions was similar between the groups. During the study period 20 patients developed surgical site infections and 7 patients other infections. In modified treatment analysis, the infection rates were 7.6% (9 patients, n = 119) in the group receiving 48 h of prophylactic antibiotic therapy and 10.2% (11 patients, n = 108) in the group receiving 72 h of prophylactic antibiotic therapy, and the difference was statistically non-significant (P > 0.05). In the per protocol analysis the infection rates were 5% (5 patients, n = 100) in the group receiving 48 h of prophylactic antibiotic therapy and 8% (8 patients, n = 100) in the group receiving 72 h of prophylactic antibiotic therapy, and the difference was again statistically non-significant (P > 0.05). The results of Fisher's exact test revealed that the duration of surgery lasting for > 5 h is an independent risk factor for surgical site infection. Forty-eight hours of a prophylactic antibiotic combination using a third-generation cephalosporin and an aminoglycoside is as effective as a 72 h regimen for preventing surgical site infection in patients undergoing CABG and valve surgery.