Surgical Site Infections and the Microbiome: Understanding the Pathogenesis of Surgical Site Infections

Inclusion Criteria: * We will include adult patients (age ≥ 18 years) * Undergoing open abdominal surgery during the study period. * Open abdominal surgery will include any abdominal procedure entering the peritoneal cavity through a midline incision with a skin incision that is 5cm or greater. Exclusion Criteria: * Patients with planned minimally invasive surgery including laparoscopic or robotic surgery as these patients have lower rates of surgical site infections (SSIs). Patients who have a laparoscopic or robotic surgery converted to open surgery will be excluded. * Appendectomy and cholecystectomy as these patients have lower risk of SSI. * Vascular, gynecological, obstetric, urological or transplantation. * Trauma patients. * Patients without source control at the index operation including those with an open abdomen, no fascial closure, or temporary abdominal closure device (such as abthera dressing). * Pediatric patients (age\<18 years). * Patients who decline swab/specimen collection.