A lack of a clear distinction between antimicrobial prophylaxis and therapy still exists in the surgical setting. Major concerns are: 1) Which surgical procedures are eligible for antimicrobial prophylaxis? 2) Which kind of antimicrobial agent should be used for surgical prophylaxis? 3) What is the optimal timing for administering antimicrobial prophylaxis and how long should administration be continued? In this paper we assess the rationales leading to the following answers: 1) Only clean-contaminated and prosthetic clean operations should be eligible for antimicrobial prophylaxis, whereas contaminated or dirty operations should be eligible for "early therapy". 2) First- or second-generation cephalosporins or aminopenicillin/beta-lactamase inhibitors are optimal choices for surgical prophylaxis, depending on location of the surgical wound. 3) The highest licensed dosage of the chosen antimicrobial agent should be administered at induction of anesthesia and redosing should be considered when the intervention lasts more than 2 antibiotic half-lives. This allows maintenance of optimal drug exposure against the potential pathogens in plasma and in the extracellular environment of the potentially contaminated tissues for the entire procedure and for some hours after wound closure. Post-surgical doses are not recommended in most cases whereas ultra-short prophylaxis is preferred.
