Background: Anastomotic leak is among the most dreaded complications in patients undergoing colorectal surgery. We have discovered that in rodents, collagenase-producing bacteria, particularly Enterococcus faecalis, promotes anastomotic leak by degrading healing anastomotic tissue. Yet, it is unclear if these organisms play a role in humans. Patients and Methods: Patients undergoing colorectal resection at the University of Chicago from July 2014 through June 2019 who developed a post-operative infection were stratified into infections that resulted from an anastomotic leak, a Hartmann pouch stump leak, or a deep infection without an associated staple line leak. Results: Forty-two patients had available culture data. Of these patients, 19 were found to have an anastomotic leak, 7 had a stump leak, and 16 had a deep infection that was not associated with a staple line. Enterococcus faecalis was identified in 24% of all infections and was associated with the development of anastomotic leak (p = 0.029). When the organisms were classified into their known ability to produce collagenase, 74% of patients with an anastomotic leak were colonized with collagenase-producing organisms, compared with only 28% of patients with a deep infection or stump leak (p = 0.022). Antibiotic-resistant organisms were more common in patients with anastomotic leak (p = 0.01). Conclusions: Collagenase-producing and antibiotic-resistant organisms are more prevalent in anastomotic leak infections compared with other deep or organ/space infections. This lends evidence to a bacterial driven pathogenesis of leak and suggests that targeting these organisms may be a novel strategy to reduce this complication.
Keywords: Enterococcus faecalis; abdominal infection; anastomosis; anastomotic leak; collagenase.