Longitudinal (2001-14) Analysis of Enterococci and VRE Causing Invasive Infections in European and US Hospitals, Including a Contemporary (2010-13) Analysis of Oritavancin in Vitro Potency

Objectives: The objective of this study was to evaluate the prevalence and in vitro susceptibility of enterococci and VRE among bloodstream infections in European and US hospitals over time.

Methods: Isolates recovered from the blood of infected patients in Europe (72 996) and the USA (67 725) between 2001 and 2014 were included in the prevalence analysis. A subset (2349) collected during 2011-13 was used for the in vitro activity analysis.

Results: Enterococcus faecium rates increased in Europe (from 1.4% in 2001 to 4.3% in 2014). These rates also increased in the USA (from 3.0% in 2001 to 5.4% in 2010), with decreasing prevalence (4.6% in 2011 to 3.6% in 2014) in later years. Enterococcus faecalis rates remained stable in Europe, but rose in the USA from 6.9% in 2001 to 8.8% in 2009, declining later (from 7.4% to 5.0%). VRE rates among E. faecalis did not vary in either region, while VRE rates among E. faecium increased in Europe (from 4.7% to 20.3%). US VRE rates among E. faecium increased until 2010 (60.0% in 2001 to 80.7% in 2010), decreasing from 75.1% in 2011 to 68.4% in 2013. Oritavancin demonstrated activity against vancomycin-susceptible E. faecalis (MIC, 0.015/0.06 mg/L; 99.5% susceptible) and vancomycin-resistant E. faecalis (MIC, 0.25/0.5 mg/L). Oritavancin showed MIC, MIC and MIC values of 0.03, 0.12 and 0.25 mg/L, respectively, for VanA E. faecium.

Conclusions: Rates of E. faecium and VRE increased in Europe. Although still elevated, VRE rates appeared to show a decreasing trend in the USA since 2010. Oritavancin demonstrated activity against enterococci, including VRE.