Patient risk factors assessed at screening include chronic uncontrolled hypertension, chronic heart disease, chronic renal disease, chronic pulmonary disease, diabetes mellitus, HIV, chronic liver disease, a BMI of less than 18 or above 40, coagulopathy, current long-term steroid use, current smoker, and current cancer. Additional assessments include PATI (Penetrating Abdominal Trauma Index), AIS and ASA scores, and adherence to SCIP prophylactic antibiotic-specific guidelines. Other measures to be documented will include antibiotic usage and surgical skin preparation. The following "present on admission" (PoA) characteristics will be collected: shock, (systolic BP < 90 mm Hg), intubation, active infection, transfusion of blood/blood products and primary injury in trauma or primary organ(s) in the acute abdomen. Intra-operative SSI risk factors including drains, staple versus sutures, surgical time (skin to skin), blood/blood products, and body temperature below 36 degrees Celsius will also be evaluated and risk adjusted in the final analysis.