Antibiotic prophylaxis for coronary bypass grafting. Comparison of a five-day and a two-day course

A trial was conducted to compare the effectiveness of a 2 day and a 5 day course of antibiotic prophylaxis after coronary bypass grafting. One hundred sixty patients were randomized to one of the two courses. The 2 day course comprised 48 hours of intramuscular kanamycin and intravenous cephalothin. The 5 day course comprised 48 hours of intramuscular kanamycin and intravenous cephalothin followed by 3 days of oral cephalexin. After the 2 day course, there were two wound infections and two respiratory tract infections in 79 patients (5.1%), and after the 5 day course, one wound infection and two respiratory tract infections in 81 patients (3.7%). Subsequently, in 171 patients undergoing coronary bypass grafting and given the 2 day course, the infection rate was 3.5%. There was no significant difference in infection rates among the three groups (p greater than 0.05). We conclude that no more than 2 days of antibiotic prophylaxis are necessary for patients undergoing coronary bypass grafting.