Timing and number of doses

It has been common practice to give antibiotics at the time of anesthesia induction, which results in adequate serum and tissue levels of the drugs; there is no consensus on whether the infusion must be completed by the time of incision. For procedures lasting less than 4 hours, Medical Letter consultants recommend a single intravenous dose of an antimicrobial started within 60 minutes before the initial skin incision, which should provide adequate tissue concentrations throughout the procedure. If vancomycin or a fluoroquinolone is used, the infusion should begin 60-120 minutes before the incision is made in order to minimize the risk of antibiotic-associated reactions around the time of anesthesia induction and ensure adequate tissue levels of the drug at the time of incision.