Understanding colonization with vancomycin resistant enterococcus in patients undergoing liver transplantation at an academic medical center

Authors:
Eugene Liu, Yuetan Dou, Kirandeep Bains, Ivy Godana, Michael De Vera, Hansel Fletcher, James Pappas

Body of Abstract:
Background: In a prior study, we found an association with hospital onset vancomycin resistant enterococcus blood stream infections (HO VRE BSI) and liver transplantation at our academic medical center, which could explain our high rate of HO VRE BSI among major teaching hospitals in California. VRE colonization may be the underlying factor driving this association. We sought to quantify and identify factors associated with VRE colonization in liver transplant patients.

Methods: To estimate the degree of carriage and to characterize risks for acquisition of VRE, we obtained rectal swabs of patients undergoing liver transplantation within 24 hours of transplantation and 9 days post-transplant. We also obtained an intraoperative swab of the donor common bile duct (CBD) to evaluate the donor liver as a source of VRE. Swabs were cultured and VRE isolated through selective media (CHROMagar VRE containing vancomycin).

Results: Among 12 patients undergoing liver transplantation thus far, 44% (4 of 9) had VRE at the time of transplant, and 67% (4 of 6) had VRE 9 days post-transplant, with 58% (7 of 12) with VRE at any time point. VRE was not isolated in any patient who underwent donor CBD swabbing (0 of 7). VRE colonization was also not associated with age, sex, nor with receipt of any antibiotic on simple logistic regression, although we did note a non-significant association with receipt of ampicillin as an inpatient 30 days prior to transplant (OR 10.0; 95%CI 0.65-154.40; p=0.10).

Conclusions: We found rates of VRE colonization both at the time of liver transplant (44%) and 9 days later (67%) that were higher than the expected rates as observed in a meta-analysis of pre (11.9%) and post (16.2%) liver transplant patients (Ziakas et al.). However, with donor CBD swabs negative for VRE, we found no evidence of acquisition of VRE from the donor liver. The high rate of colonization in liver transplant patients may explain the higher rate of HO VRE BSI at our institution. Ongoing surveillance of liver transplant patients, particularly for HO VRE BSI, may help to clarify this association and the mechanisms of VRE colonization.