Vancomycin-resistant enterococcus acquisition in a tertiary care hospital: Testing the roles of antibiotic use, proton pump inhibitor use, and colonization pressure

Background. Vancomycin-resistant Enterococcus (VRE) is a leading cause of healthcare-associated infections, and asymptomatic colonization precedes infection. VRE continues to spread despite widespread application of pathogen-specific control guidelines. A better understanding of the risk factors for transmission is needed. Methods. A retrospective matched case-control study was performed from June 2013 through December 2016 in a single institution. Patients in 6 intensive care units, 1 hematology and oncology unit, and 1 bone marrow transplant unit were screened by means of rectal swab sampling on admission and weekly thereafter. Case patients had a negative swab sample followed by a positive sample >3 days after admission. Controls were closely matched to case patients based on time from admission to the second swab sample, unit in which the second sample was obtained, and date of admission. Comorbidity data, procedures, healthcare settings and exposures, culture data, and duration of antibiotic and proton pump inhibitor (PPI) therapy were abstracted from the electronic medical record. A multivariable risk factor model for conversion was generated using purposeful selection. Results. A total of 551 case patients were matched with controls. The largest modifiable effects on VRE acquisition were ≥1 day of vancomycin therapy (odd ratio, 1.98; P < .001), ≥1 day of aerobic antibiotic therapy (1.90; P < .001), and a dose-dependent effect of PPI therapy (odds ratio per day of therapy, 1.09; P < .001). Colonization pressures from patients identified to be carriers and placed in contact precautions did not confer increased risk. Conclusions. Decreasing PPI use and preventing the inappropriate initiation of antibiotic therapy are modifiable targets to decrease VRE transmission in the hospital.