Colonization with Vancomycin-Resistant Enterococci and Subsequent Risk of Bacteremia in Hematopoietic Stem Cell Transplant Recipients

Background: Vancomycin-resistant enterococci (VRE) are common causes of bacteremia in hematopoietic stem cell transplant (HSCT) recipients. Understanding rates of VRE colonization and risk of subsequent VRE bacteremia in these patients may inform decisions related to the use of empirical VRE-active therapy.

Methods: VRE colonization was prospectively assessed by perianal swabs on admission for HSCT and weekly thereafter until neutrophil engraftment in adult HSCT recipients from December 2013-December 2015 at our center. The proportion of patients colonized on admission and rates of VRE acquisition and bacteremia were determined.

Results: Of 326 HSCT recipients (197 allogeneic, 129 autologous), 22% were colonized with VRE on admission. Patients with allogeneic HSCT were more likely to be colonized on admission than those with autologous HSCT (28% vs. 12%, p<0.001). If not colonized on admission, allogeneic HSCT recipients were also more likely than autologous HSCT recipients to acquire VRE during their transplant hospitalization (52% vs. 20%, p<0.001). The risk of VRE bacteremia within 30 days after transplantation was significantly greater in allogeneic HSCT recipients who were colonized on admission (10/55, 18%) than those who were not colonized (6/140, 4%; p=0.003). No baseline demographic factors (e.g. age, sex, malignancy, donor type, conditioning regimen) were significantly associated with VRE bacteremia in colonized allogeneic HSCT recipients. Median time from HSCT to VRE bacteremia was 8.5 (range: -4, 14) days. Importantly, 7/55 allogeneic HSCT recipients (13%) who were colonized with VRE on admission developed VRE bacteremia during their first episode of fever and neutropenia, while receiving levofloxacin prophylaxis. Only 1 autologous HSCT recipient developed VRE bacteremia.

Conclusion: Allogeneic HSCT recipients have high rates of VRE colonization on admission for transplant. In the setting of levofloxacin prophylaxis, colonized patients are at increased risk for VRE bacteremia, which often occurs during the first episode of fever and neutropenia. Assessment for VRE colonization in allogeneic HSCT recipients may identify potential candidates for early VRE-active therapy in centers with high rates of VRE infection.