Source: Masters Abstracts International, Volume: 57-05.

Adviser: Melinda M. Pettigrew.

Introduction: Intensive care unit (ICU) patients undergo a disruption in their gut microbiome that leaves them vulnerable to colonization with vancomycin-resistant Enterococcus (VRE). VRE colonization typically precedes VRE infection, thus understanding the factors involved in colonization is critical to developing effective control methods.

Objectives: Determine the prevalence and risk factors of VRE colonization and the incidence of subsequent VRE infection among VRE colonized and VRE not-colonized ICU patients. Methods: Two peri-rectal swabs were collected from 116 patients admitted to ICUs at the University of Maryland Medical Center (UMMC) between September 5, 2001 and March 21, 2009. Demographic and clinical data were obtained from the UMMC Central Data Repository and chart review. The swabs were cultured in real-time for VRE. 16SrRNA gene sequencing of DNA obtained from the swabs, in house scripts, and USEARCH software were used to determine the taxonomic categories and relative abundance of bacteria.

Results: Thirty-three (28.5%) patients were colonized with VRE. VRE colonized patients had longer ICU stays (p=0.02) and more medical conditions, compared to VRE not-colonized patients. The VRE colonized cohort had a higher proportion of patients receive specific antibiotics including piperacillin-tazobactam (p=0.007), vancomycin (p=0.023), and anti-pseudomonal antibiotics (p=0.001), compared to those who were not VRE colonized. Among the VRE colonized patients, 16 (48.5%) developed VRE infections. Among the VRE not-colonized patients, 11 (13.3%) developed VRE infections. For swabs 1 and 2, Enterococcus domination was associated with a higher number of VRE infections (p<0.001 and p=0.011, respectively), compared to those without Enterococcus domination.

Conclusion: VRE colonized patients were approximately 3.5 times more likely to develop a VRE infection compared to VRE not-colonized patients. This finding indicates the importance of determining which patients have been colonized with VRE. Future research should focus on identifying clinically equivalent antibiotics that have the least harmful impact on the gut microbiome.