Urinary Tract Infections After Colorectal Cancer Surgery: Incidence, Microbiology, Antimicrobial Resistance, and Risk Factors

Background/Objectives: Postoperative urinary tract infections (UTIs), particularly catheter-associated UTIs (CAUTIs), are potentially preventable complications of colorectal surgery. This study evaluated their incidence, timing, microbiology, antimicrobial resistance, and associated factors among patients undergoing colorectal cancer surgery. Methods: This prospective cohort study included 300 patients undergoing colorectal cancer surgery at a Serbian tertiary hospital. Associations with postoperative UTI, defined according to ECDC criteria, were examined using Firth penalized logistic regression and cause-specific Cox regression, with cumulative catheter exposure modeled as a time-dependent covariate. Results: Nineteen patients (6.3%) developed postoperative UTI, including 17 CAUTIs (89.5%) and two asymptomatic bacteriuria. The incidence rates of all UTIs and CAUTIs were 12.0 (95% confidence interval [CI], 7.2–18.8) and 10.8 (95% CI, 6.3–17.2) per 1000 catheter-days, respectively. Seventeen infections occurred by postoperative day 30, and no additional events occurred after day 45. In the multivariable Firth penalized logistic regression model, cumulative catheter exposure per five catheter-days (adjusted odds ratio [aOR], 1.45; 95% CI, 1.17–1.84), operative duration per 30 min (aOR, 1.59; 95% CI, 1.13–2.21), and preoperative leukocyte count (aOR, 1.20; 95% CI, 1.02–1.42) were associated with UTI. In the primary Cox model, cumulative catheter exposure (adjusted hazard ratio [aHR], 2.66; 95% CI, 2.03–3.50) and operative duration (aHR, 1.60; 95% CI, 1.16–2.21) remained associated with postoperative UTI after adjustment for the other covariates included in the model. Gram-negative organisms predominated, with notable third-generation cephalosporin and carbapenem resistance among Klebsiella–Enterobacter isolates. Conclusions: Most surveillance-defined postoperative UTI events were symptomatic and catheter-associated. Greater cumulative catheter exposure and longer operative duration showed consistent associations with UTI across exploratory models. These findings support careful review of catheter necessity but require confirmation in larger cohorts.