Antibiotic prophylaxis in colorectal surgery: are oral, intravenous or both best and is mechanical bowel preparation necessary?

Combined OA and IV is superior to either alone in preventing SSI. The certainty of evidence is such that further research is unlikely to alter this relationship when MBP is used. In randomized trials of MBP, OA plus IV shows no benefit from MBP versus no MBP. The last comparison shows in just two studies that as in the first meta-analysis, but in the absence of MBP, combined OA plus IV is also superior to IV alone.