Trends in incidence of vancomycin-resistant enterococcus colonization and bacteremia among hematopoietic cell transplant recipients at a large comprehensive cancer care center

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) are important hospital-acquired pathogens among hematopoietic cell transplant (HCT) recipients. We examined the incidence and outcomes of patients with VRE colonization and bacteremia (VREB) over a ten-year period at a center that routinely screens and uses barrier precautions for VRE.

METHODS

Adults receiving their first allogeneic HCT at our center between September 2007 and August 2016 were eligible for inclusion. Patients who were positive either by standardized pre-HCT stool/rectal screening or at any point two years prior to HCT were considered VRE colonized. Patients with acquired VRE were those with positive VRE cultures only post-HCT. Colonization and 100-day post-HCT VREB incidence rates were compared over time using linear regression. Cox proportional hazards models were constructed to assess the relationship between 100-day mortality and: a) pre-HCT colonization, and b) the number of days with sequential VREB cultures. Pre-transplant Assessment of Mortality (PAM) scores were calculated to allow adjustment for underlying disease severity.

RESULTS

Of 1,492 eligible HCT recipients, 203 (14%) were colonized with VRE pre-HCT; an additional 90 (6.0%) acquired VRE colonization post-HCT. Forty-two patients (2.8%) developed VREB, the majority among those colonized with VRE (32 [76%] vs. 10 [24%] non-colonized). The cumulative incidence of VREB for the cohort was 2.9 per 10,000 patient-days. Over the study period, there were no significant changes in VRE colonization or VREB (p-values>0.1). Those with multiple days with positive VRE blood cultures had higher mortality than those with one positive culture (HR 3.23; 95%CI: 0.88, 11.8). Patients with pre-HCT colonization had an increased risk of death compared to non-colonized patients in an unadjusted model (HR 2.1: 95%CI: 1.4, 3.2) and after adjustment by PAM score (HR = 2.2; 95%CI: 1.5, 3.3). Patients with higher PAM scores and VRE colonization pre-HCT had higher mortality than non-colonized patients with high PAM scores.

CONCLUSION

Despite nearly 15% of patients with pre-HCT colonization in our cohort, VREB was an infrequent post-HCT complication. We identified a subgroup of patients at high risk of VREB who may be targeted for VRE-specific measures. Studies examining the impact of antimicrobial stewardship programs are needed to inform infection prevention interventions.