Outcomes and factors associated with mortality for Enterococcus faecalis and Enterococcus faecium bloodstre am infections: a prospective multi-centre cohort study from the PROBAC project

Abstract

Background Enterococcal BSI represents significant morbidity and mortality, with fatality rates of approximately 20-30%. Infections by E. faecalis and E. faecium have microbiological and clinically differences. Moreover, several studies have demonstrated higher mortality rates in E. faecium BSI. This study aims to explore differences in mortality for E. faecalis and E. faecium BSI and identify prognostic factors associated with poor outcome. Methods The study is a post-hoc analysis of the PROBAC project, a national multicenter, observational, prospective cohort study conducted in 26 Spanish hospitals between October 2016 and March 2017. All patients with monomicrobial E. faecalis and E. faecium BSI were included (Figure 1). Multi variable logistic regression was performed to explore the association of species with all-cause mortality and to identify the prognostic factors in patients with E. faecalis BSI and E. faecium BSI. Results 307 patients with monomicrobial enterococcal BSI were included, 186 (60.6%) by E. faecalis and 121 (39.4%) E. faecium . Median age was 71 (IQR 61-82), 65.2% was male. Population characteristics and univariate analysis of factors associated with mortality are shown in Table 1. All-cause mortality was 20.8% (64 patients). In a multivariable model (Table 2A), no difference in mortality for patients with BSI due to E. faecium versus E. faecalis was found (OR=1.04 (95%CI=0.54-1.97), p=0.914). Regarding E. faecalis BSI, Charlson Comorbidity Index ≥3 (OR=3.22 (1.16-8.94), p=0.025), congestive heart failure (OR 3.06 (1.23-7.59), p=0.016) and SOFA score ≥3 (OR 10.63 (3.96-28.6), p<0.001) were independent predictors of mortality (Table 2B). For E. faecium BSI, only SOFA score ≥3 (OR 3.25 (1.20-8.80), p=0.020), was an independent prognostic factor (Table 2C). Conclusions Enterococcal BSI was associated with significant mortality. This study was not able to show a difference in mortality between E. faecalis and E. faecium BSI. Furthermore, our results showed that clinical severity at BSI onset is associated with mortality in both E. faecalis BSI and E. faecium BSI. By contrast, the burden of comorbidity is only associated with prognosis of E. faecalis BSI.