Elective colorectal surgery

Common Pathogens

Enterobacterales
Anaerobes


Regimen(s) of Choice
See General Principles and Pre-Op Antibiotic Administration and Intraoperative Antibiotic Administration
Mechanical bowel preparation    
then    
[Neomycin 1g PO at 1300h, 1500h, 2000h day before surgery
+    
Metronidazole] 1g PO at 1300h, 1500h, 2000h day before surgery
+    
[Cefazolin 2g IV x 1 pre-op dose
+    
Metronidazole] 500mg IV x 1 pre-op dose

Alternative Regimens if allergy to cefazolin, or severe non-IgE-mediated reaction to any β-lactam (interstitial nephritis, hepatitis, hemolytic anemia, serum sickness, severe cutaneous reactions [e.g. SJS, TEN, DRESS])
Mechanical bowel preparation    
then    
[Neomycin 1g PO at 1300h, 1500h, 2000h day before surgery
+    
Metronidazole] 1g PO at 1300h, 1500h, 2000h day before surgery
+ either of these 2 IV regimens:    
[Gentamicin 1.5mg/kg IV x 1 pre-op dose
+    
Clindamycin] 600mg IV x 1 pre-op dose
or    
[Gentamicin 1.5mg/kg IV x 1 pre-op dose
+    
Metronidazole] 500mg IV x 1 pre-op dose