Perioperative antibiotic prophylaxis timing?

• A. Within 60 minutes before incision (60-120 minutes for some agents) and redosed as needed for long procedures.
• B. Immediately after incision only.
• C. Only after closure.
• D. Not needed unless infection present.

Answer: (A)

Timing antibiotics to match the moment the incision is made is essential for effective prophylaxis. The goal is to have adequate drug levels in the tissues at the time of the incision so that bacteria introduced during surgery are rapidly suppressed.

Most agents should be given within 60 minutes before incision so tissue concentrations are highest right when the wound is opened. Some drugs require longer infusion times and should be started earlier, typically 60–120 minutes before incision (for example, agents like vancomycin or certain fluoroquinolones). In long procedures or those with substantial blood loss, you redose to maintain protective levels, following the drug’s recommended interval (often every 2–4 hours, depending on the agent and patient factors).

Other timing options—immediately after incision, only after closure, or not needed unless infection is present—do not provide the protective tissue levels when the wound is first contaminated, so they are not appropriate for prophylaxis. Thus, administering within 60 minutes of incision (or 60–120 minutes for longer-infusion drugs) and redosing for lengthy procedures aligns with best practice for preventing surgical site infections.