colonization and the frequency of subsequent treatment for infection in critically ill patients.

Objective: To determine risk factors for colonization and infection (CDI) among patients admitted to the intensive care unit (ICU).

Design: Retrospective observational cohort study.

Setting: Tertiary-care facility.

Patients: All adult patients admitted to an ICU from July 1, 2015, to November 6, 2019, who were tested for colonization. Patients with CDI were excluded.

Methods: Information was collected on patient demographics, comorbidities, laboratory results, and prescriptions. We defined colonization as a positive nucleic acid amplification test for up to 48 hours before or 24 hours after intensive care unit (ICU) admission without evidence of active infection. We defined active infection as the receipt of an antibiotic whose only indication is the treatment of CDI. The primary outcome measure was the development of CDI up to 30 days after ICU admission. Logistic regression was used to model associations between clinical variables and the development of CDI.

Results: The overall colonization rate was 4% and the overall CDI rate was 2%. Risk factors for the development of CDI included colonization (aOR, 13.3; 95% CI, 8.3-21.3; < .0001), increased ICU length of stay (aOR, 1.04; 95% CI, 1.03-1.05; < .0001), and a history of inflammatory bowel disease (aOR, 3.8; 95% CI, 1.3-11.1; = .02). Receipt of any antibiotic during the ICU stay was associated with a borderline increased odds of CDI (aOR, 1.9; 95% CI, 1.0-3.4; = .05).

Conclusion: colonization is associated with the development of CDI among ICU patients.