TCRN Practice Exam 2026 – Complete Prep for Your Test

The most common organism found in surgical site infections after a clean-contaminated procedure is Escherichia coli. In clean-contaminated surgeries, there is a direct involvement with the gastrointestinal tract, which is a primary reservoir for this organism. Escherichia coli is part of the normal flora in the intestines and can easily be introduced into the surgical site during procedures where there is potential for contamination from bowel contents.

Compared to Staphylococcus, which is more often associated with skin flora and incisional infections, or Streptococcus and Peptostreptococcus, which are less common in gastrointestinal origin infections, Escherichia coli is specifically linked to infections that arise after surgeries involving the gastrointestinal tract. Its prevalence in surgical site infections reflects its ability to cause both straightforward and complicated infections due to its robust virulence factors and resistance capabilities.