After intestinal anastomosis — resection and reconnection of intestinal segments — the intestine sometimes fails to heal. Leakage, peritonitis, and sepsis can result: in other words, anastomotic leak. The underlying cause of this complication is unknown, but evidence is growing that intestinal microbes play a role.

Authors of this paper showed the commensal bacterium Enterococcus faecalis contributes to the development of anastomotic leak in rats by degrading collagen and activating tissue matrix metalloproteinase 9 (MMP9) in the intestinal tissues.

Researchers prevented anastomotic leak in the rodents in two ways: either by eliminating E. faecalis through a topical antibiotic on the intestinal tissues or by suppressing intestinal MMP9 activation. Antibiotics administered intravenously did not eliminate the bacteria or prevent anastomotic leak.

A human part of the study showed that, even after receiving intravenous antibiotics for colon surgery, patients’ anastomotic tissues still contained E. faecalis.

This original research was highlighted in a Nature Reviews Gastroenterology & Hepatology article called, “Commensal bacteria and intestinal surgery complications“. In this short piece, study co-author John Alverdy notes that in this example, multiple events must happen in order to render a commensal bacteria harmful. He says clinicians can use the information from this study to work toward prevention of anastomotic leak, since current uses of antibiotics for intestinal surgery are “probably inadequate.”


Shogan BD, et al. (2015) Collagen degradation and MMP9 activation by Enterococcus faecalis contribute to intestinal anastomotic leak. Science Translational Medicine DOI: 10.1126/scitranslmed.3010658

Weber C. (2015) Commensal bacteria and intestinal surgery complications. Nature Reviews Gastroenterology & Hepatology doi:10.1038/nrgastro.2015.92