The DECREASE SSI Trial (Decolonization to Reduce After-Surgery Events of Surgical Site Infection) is a two-arm multi-center individual placebo-controlled randomized (2,700 participants randomized 1:1) clinical trial to reduce post-discharge surgical site infection following open colon or small bowel surgery by comparing chlorhexidine bathing plus nasal mupirocin in the 30 days following discharge to soap without antiseptic properties (placebo) and placebo nasal ointment. This trial seeks to enhance the care of the 675,000 patients annually who undergo colon and small bowel surgery by finding simple and efficacious interventions to reduce SSI.