But one of the most significant steps to ensure patient safety during and after an impending trip under the knife passes mostly unnoticed: The dose of antibiotics that many surgical patients receive shortly before moving from a staging area into the operating room itself. That’s where the antibiotics come in. But as more and more bacteria show resistance to antibiotics, the risks change — to the point that doctors and patients alike may soon face agonizing choices about whether or when to take a chance on many of the surgeries we now accept as a matter of course. As of 2011, there were an estimated 157,500 surgical site infections . In large measure, that infections associated with surgery are under control.