Surveillance strategies and impact of vancomycin-resistant enterococcal colonization and infection in critically ill patients

Objective: To determine the optimal site and frequency for vancomycin-resistant enterococci (VRE) surveillance to minimize the number of days of VRE colonization before identification and subsequent isolation. Summary Background Data: The increasing prevalence of VRE and the limited therapeutic options for its treatment demand early identification of colonization to prevent transmission. Methods: The authors conducted a 3-month prospective observational study in medical and surgical intensive care unit: (ICU) patients with a stay of 3 days or more. Oropharyngeal and rectal swabs, tracheal and gastric aspirates, and urine specimens were cultured for VRE oh admission to the ICU and twice weekly until discharge. Results: Of 117 evaluable patients, 23 (20%) were colonized by VRE. Twelve patients (10%) had VRE infection. Of nine patients who developed infections after ICU admission, eight were colonized before infection. The rectum was the first site of colonization in 92% of patients, and positive rectal cultures preceded 89% of infections acquired in the ICU. This was supported by strain delineations using pulsed-field gel electrophoresis. Twice-weekly rectal surveillance alone identified 93% of the maximal estimated VRE-related patient-days; weekly or admission-only surveillance was less effective. As a test for future VRE infection, rectal surveillance culture twice weekly had a negative predictive value of 99%, a positive predictive value of 44%, and a relative risk for infection of 34. Conclusions: Twice-weekly rectal VRE surveillance of critically ill patients is an effective strategy for early identification of colonized patients at increased risk for VRE transmission, infection, and death.