Clinical epidemiology of vancomycin-resistant Enterococcus gallinarum and Enterococcus casseliflavus bloodstream infections

• 30-day mortality was 10.4% among vanC-type vancomycin-resistant enterococcal bloodstream infections (VRE BSIs).
• Composite treatment failure was 39.6% among vanC-type VRE BSIs.
• Treatment with anti-VRE agents lowered treatment failure in vanC-type VRE BSIs.

This study aimed to evaluate the clinical outcomes of vancomycin-resistant enterococcal bloodstream infections (VRE BSI) caused by Enterococcus gallinarum or Enterococcus casseliflavus. Variables associated with treatment failure were determined and treatment options were compared. This was a national retrospective study of hospitalised Veterans Affairs patients with non-faecium, non-faecalis VRE BSI. The primary outcome was treatment failure, defined as a composite of: (i) 30-day all-cause mortality; (ii) microbiological failure; and (iii) 30-day VRE BSI recurrence. Stepwise Poisson regression was conducted to determine variables associated with treatment failure. In total, 48 patients were included, with 29 cases (60.4%) caused by E. gallinarum and 19 cases (39.6%) caused by E. casseliflavus. Among these cases, 20 (41.7%) were treated with an anti-VRE agent (linezolid or daptomycin) and 28 (58.3%) were treated with an anti-enterococcal β-lactam. Overall, 30-day mortality was 10.4% (5/48) and composite treatment failure was 39.6% (19/48). In multivariable analysis, treatment with an anti-enterococcal β-lactam was associated with increased treatment failure in comparison with anti-VRE therapy (adjusted risk ratio = 1.73, 95% confidence interval 1.06–4.97; P = 0.031). Overall, treatment with linezolid or daptomycin for vancomycin-resistant E. gallinarum or E. casseliflavus BSI resulted in improved clinical outcomes in comparison with anti-enterococcal β-lactam treatment.