Rationale: The surgical complication of intestinal anastomotic leak remains a clear and present danger to patients despite advances in surgical technique and ever more powerful antibiotics. No surgeon is immune from this complication and leak rates have not changed in decades. The consequences of a leak (peritonitis, sepsis, death) can be so severe that in the case of rectal cancer, diverting ileostomies are routinely performed to divert the fecal stream away from the healing anastomosis. We have recently discovered that certain intestinal bacteria, with the capacity to express collagenase and cleave MMP9 (Matrix metallopeptidase 9) to its active collagen degrading form, play a key and causative role in anastomotic leak. These bacteria often escape elimination due to the failure of current antibiotic regimens and their delivery methods to remain functionally durable at anastomotic tissue sites.