Question

When should a prophylactic antibiotic be administered before elective entry into the GI tract (e.g., elective cholecystectomy)?

• A. Within 1 hour before incision
• B. 4 hours before incision
• C. 6 hours before incision
• D. At the time of skin closure

Hint:

Peak drug level must coincide with the moment of incision.

Answer 1

The Correct Option is A

Step 1: Principle of surgical antibiotic prophylaxis. The aim is to have an adequate tissue and serum drug concentration at the moment of incision and throughout the period of contamination.

Step 2: Recommended timing. The prophylactic antibiotic should be given within 60 minutes (30-60 min) before skin incision. For vancomycin or fluoroquinolones, infusion may begin up to 120 minutes before because of slower administration.

Step 3: Why the others are wrong. Giving the drug 4 or 6 hours earlier means levels fall before contamination occurs, defeating the purpose. Administering it only at closure is too late, as bacterial seeding has already happened during the procedure.

Key fact: Surgical antibiotic prophylaxis is best given within 30-60 minutes before incision, i.e. within 1 hour.