A 5-Year Epidemiological Study of Monomicrobial Enterococcal Bloodstream Infection in a Population-Based Cohort

Background The incidence, epidemiology, and clinical characteristics of enterococcal bloodstream infection have not previously been studied on a population-based level in the United States. Methods We utilized the Expanded Rochester Epidemiology Project medical records linkage system to conduct a contemporary five-year, retrospective, population-based study of monomicrobial enterococcal bloodstream infection among adult residents of eight counties in southeast Minnesota from January 1, 2018 to December 31, 2022. Results A total of 109 cases of monomicrobial enterococcal bloodstream infection were identified. The overall age- and sex-adjusted incidence rate was 6.7 per 100,000 person-years (95% confidence interval, 5.4-7.9). Multivariable analysis revealed that male sex (p < 0.001) and older age (p < 0.001) were each independently associated with increased incidence, whereas no temporal association was demonstrated (year effect, p = 0.475). The median age of incident cases was 76.8 years (interquartile range, 65.0-83.3). Urinary tract source was the most common presumed source (41.3%), and Enterococcus faecalis was the predominant (83.5%) pathogen. Overall, 14.4% of patients met modified Duke criteria for definite infective endocarditis. Cumulative mortality was 28.4% at 12 weeks and 43.1% at 1 year. Conclusions In this population-based study, monomicrobial enterococcal bloodstream infection was significantly associated with older age and male sex. There was a high rate of mortality at 12 weeks and 1 year, with approximately 1 out of 7 cases complicated by definite infective endocarditis. These findings underscore the importance of ongoing investigation of this syndrome.