Background and Aims Vancomycin-resistant enterococci (VRE) are among the most feared hospital pathogens. The present nested case-control study aimed to determine the prevalence and risk factors of enteric colonization of VRE in ICUs in a tertiary hospital in Iran.

Methods Serial rectal swabs were obtained every five days from all hospitalized patients (70 cases) in six ICUs and one CCU until patient’s discharge. During the study 100 samples of rectal swab in sterile situation were taken. Then enterococci detection and susceptibility were done by disk diffusion and MIC dilution method.

Results A total of 9 of the 70 patients (12.85%) were colonized with VRE. five patients who had at least a negative test for VRE - at the time of hospitalization- were colonized with resistant enterococci which demonstrated an incident rate of colonization as 7% at three months of study period. Univariate analysis showed that prior antibiotic consumption, vancomycin and third generation cephalosporins, and duration of vancomycin use were significant risk factors for VRE colonization(p<0.05). There were no significant association between prevalence of VRE and variables such as age, ward, history of admission, history of antibiotic use, duration of hospitalization and underlying disease (p>0.05). The logistic regression showed that the consumption of vancomycin was the independent risk factors for VRE colonization.

Conclusions Prevalence of VRE in ICUs in the present study was high in consistence with national studies confirming that this organism might be endemic in tertiary large hospitals in Iran.