Clinical outcomes of bloodstream infections (BSI) due to Vancomycin-Resistant Enterococcus faecium (VRE)

Background:

Treatment options for VRE infections are limited. We defined our VRE antibiogram, and evaluated clinical responses among patients (pts) treated for VRE BSI.

Methods:

Retrospective review of consecutive pts with VRE BSI (2012-15). Ampicillin susceptible (S) or E. faecalis isolates were excluded. Clinical success was defined as 30 day (d) survival with clinical improvement and absence of persistent or recurrent VRE BSI.

Results:

98 pts were enrolled. Median age was 58 years (range: 21 – 86). 60% were men. 62% were immunocompromised. At onset of VRE BSI, 73% were in an ICU, 43% required renal replacement therapy, and median Pitt Bacteremia Score (PBS) was 7 (0- 13). Portals of entry were central venous catheters in 35% and abdomen in 34%. Using microscan or Etest, 22% and 1% of VRE were daptomycin (DAP) and linezolid (LZD) NS, respectively (P<0.001). 30d survival and clinical success rates were 63% and 41%, respectively. Success rates were similar among pts treated with DAP (44% [17/39]), LZD (39% [22/56]), or quinupristin-dalfopristin (33% [1/3]). LZD success was 39% and 45% against DAP-NS and –S , respectively. LZD was utilized more often against DAP-NS than DAP-S isolates (P=0.01). By multivariate analysis, PBS was associated with failure (P=0.08). Treatment was discontinued in 5% and 21% of pts on DAP or LZD, respectively, due to adverse events or persistent infection (P=0.04). Rates of recurrent BSI (8% within 90d of initial BSI) did not vary between agents. 63% of recurrent VRE isolates were DAP-NS; 0% were LZD-NS (P=0.025). 88% and 63% of pts with recurrent BSI were previously exposed to DAP or LZD, respectively. 63% and 37% of pts with recurrent BSI were treated with the same or alternative agent, respectively. 25% of pts died during recurrent BSI treatment; another 25% had a third VRE BSI within 90 d.

Conclusion:

Clinical success was achieved in a minority of patients treated for VRE BSI, despite the use of agents that were active in vitro. It was particularly worrisome that 22% of VRE were DAP-NS, and 21% of pts on LZD discontinued treatment. New, better-tolerated agents for VRE are needed. Microscan/Etest may assign higher DAP MICs than broth microdilution methods, but our results suggest that potential over-calling of DAP-NS did not impact outcomes.