Principles of antimicrobial prophylaxis

The most important principle in surgical antibiotic prophylaxis is to ensure high blood levels of antibiotic at the time of anticipated wound contamination. This is best achieved by intravenous administration commenced at the time of induction of anesthesia. The continued efficacy of prophylaxis depends on the implementation of policies that minimize the opportunities for bacteria to acquire resistance to antibiotics. Prophylaxis should, therefore, be used judiciously and restricted to operations for which it is of established benefit. These are mainly operations in which a viscus colonized by bacteria is opened and in which bacterial contamination is unavoidable. Prophylaxis is also used for certain cardiovascular and orthopedic implant operations in which septic complications are a major threat to a successful outcome and to the life of the patient. The choice of antibiotic should be based on knowledge of the bacterial species likely to contaminate the wound and cause infection. The duration of prophylaxis should be short, and should not be extended beyond the minimum period known to be effective. Controlled trials have established that a single dose of antibiotic is sufficient for many operative procedures and that there is no benefit in prolonging prophylaxis beyond the period when the open wound is exposed to bacterial contamination .