For prophylaxis in clean-contaminated GI surgery, antibiotics should be given within how many minutes before incision, and which combination is typical for colorectal procedures?

For prophylaxis in clean-contaminated GI surgery, antibiotics should be given within how many minutes before incision, and which combination is typical for colorectal procedures?

• A. Within 120 minutes before incision; vancomycin alone
• B. Within 30 minutes before incision; cefazolin alone; redosing if contaminated
• C. Within 24 hours after incision; cefazolin with metronidazole; no redosing
• D. Within 60 minutes before incision; cefazolin with metronidazole; redosing if prolonged

Answer: (D)

Prophylaxis works best when protective drug levels are present at the moment of incision. For clean-contaminated GI surgery, you want coverage for the mixed flora that includes anaerobes from the colon, not just skin flora. Administering an effective combination within about 60 minutes before the incision ensures adequate tissue levels at cut time. Cefazolin handles the aerobic gram-positive and some gram-negative bacteria, but colorectal flora includes anaerobes, so metronidazole is added to cover those organisms. If the operation is prolonged or there’s significant blood loss, you redose to maintain levels throughout the procedure. This approach—drug mix of cefazolin with metronidazole and redosing for long surgeries—fits colorectal prophylaxis best.

Prophylaxis works best when protective drug levels are present at the moment of incision. For clean-contaminated GI surgery, you want coverage for the mixed flora that includes anaerobes from the colon, not just skin flora. Administering an effective combination within about 60 minutes before the incision ensures adequate tissue levels at cut time. Cefazolin handles the aerobic gram-positive and some gram-negative bacteria, but colorectal flora includes anaerobes, so metronidazole is added to cover those organisms. If the operation is prolonged or there’s significant blood loss, you redose to maintain levels throughout the procedure. This approach—drug mix of cefazolin with metronidazole and redosing for long surgeries—fits colorectal prophylaxis best.