Enterococcal bacteremia: risk factors for vancomycin resistance and predictors of mortality

Abstract

Objective: To identify risk factors for vancomycin resistance and mortality in enterococcal bacteremia.

Design: Historical cohort study.

Setting: A large academic medical center with a high prevalence of vancomycin-resistant enterococci (VRE).

Patients: Two hundred sixty patients with enterococcal bacteremia, of whom 72 (28%) had VRE.

Results: Independent risk factors for infection with VRE were the mean number of antibiotic days (P<.001), renal insufficiency (P<.001), mean days of vancomycin use (P = .005), and neutropenia (P = .013). A trend toward a significant association between metronidazole use and VRE also was noted (P = .068). Mortality was attributable to the bacteremia in 96 patients (37%). Severity of illness (P<.001) and age (P = .020) were independent risk factors for mortality. Vancomycin resistance was not, however, an independent predictor of mortality.

Conclusion: These results suggest that restrictions on antibiotic use, particularly in patients with renal insufficiency and neutropenia, may help to combat the rising incidence of VRE. Although patients with VRE bacteremia demonstrated higher mortality rates than patients with infection due to susceptible isolates, vancomycin resistance was not an independent predictor of mortality in these patients and likely serves more as a marker of underlying severity of illness.