Understanding the emergence of vancomycin resistant enterococcus at an academic medical center in California

Author(s):
Eugene Liu; Hala Nashed; James Pappas

Background:

Since 2016, our academic medical center in California has had rates of hospital onset vancomycin resistant enterococcus blood stream infections (HO VRE BSI) above the statewide rate among major teaching hospitals.

Hypothesis:

We sought to identify factors associated with the high rate of HO VRE BSI.

Methods:

We conducted retrospective case control studies, comparing cases of HO VRE BSI with controls with HO VSE (vancomycin sensitive enterococcus) BSI. HO BSI were defined as a positive blood culture specimen in an inpatient collected ≥72 hours after hospital admission. Cases and controls were identified from microbiology records January 2020–October 2023. For each hospitalization complicated by HO BSI, we compared sex, age, and specific admission diagnoses of inpatients. In secondary analysis, we compared liver transplant recipients at our institution January 2019–October 2023 with/without HO VRE BSI by sex, age, and admission diagnoses at time of transplant and inpatient antibiotics received in the 6 months prior to transplant.

Results:

Among 66 cases and 65 controls, age and status as a solid organ transplant recipient were associated with increased odds of HO VRE BSI on simple logistic regression and remained independently associated on multiple logistic regression (age OR 1.03; 95%CI 1.01-1.04 and transplant status OR 13.16; 95%CI 1.64-105.78). Consistent with our findings, the incidence density rate of HO VRE BSI of 20 California transplant centers in 2022 positively correlated with the number of transplants reported to the Organ Procurement and Transplantation Network in 2022 (R² = 0.5143, p<0.00037). Among liver transplant recipients, we identified 13 cases and 509 controls with/without HO VRE BSI. An admission diagnosis of ESRD and receipt of ertapenem were associated with increased odds of HO VRE BSI on simple logistic regression and remained independently associated on multiple logistic regression (ESRD OR 16.99; 95%CI 3.96-72.83 and receipt of ertapenem OR 3.33; 95%CI 1.78-6.20).

Conclusions:

The association of HO VRE BSI with transplant status and positive correlation between the number of transplants and rate of HO VRE BSI in California transplant centers could explain the higher rate of HO VRE BSI our institution. These results, in combination with secondary analysis on liver transplant patients, suggest infection control measures for VRE should focus on transplant populations, particularly those with concurrent ESRD, as well as antibiotic stewardship with broad spectrum antibiotics.