Assessing the role of prophylactic antibiotics in clean surgery

Abstract

The perception that prophylactic antibiotics are not worthwhile in clean surgery has been challenged in two ways: firstly by Platt et al.1,2 who found a trend in favour of prophylaxis in hernia and breast surgery and, secondly in surveillance of surgical wound infection (SWI),3–5 where higher rates of infection that previously recognised are found. It is appropriate to analyse the role of antibiotic prophylaxis in clean surgery in the light of these challenges. Infections originating during surgery (intraoperative infections) will lie deep in the wound and may lead to abscess formation and other deep infections. They usually appear in the early post-operative period, within seven days of surgery. Infections arising post operatively usually originate from sources external to the wound from cross infection or auto infection. They are more superficial and usually develop more than seven days after operation.6 Prophylactic antibiotics are aimed only at preventing intra-operative infections, these being more severe and occurring over a shorter time period. If SWI rates are calculated from one time point at 4–6 weeks after surgery, as in the studies quoted above, the total will include those infections originating from surgery, as well as those originating post operatively. Prophylactic antibiotics can have no affect on the latter. What are the relative contributions of intraand post-operative infections to the total? Unfortunately, published surveys do not separate them, but indirect estimates can be made