Vancomycin-resistant Enterococcus characterization

A collection of previously characterized isolates of E. faecium (n = 13), Enterococcus faecalis (n = 11), Enterococcus gallinarum, Enterococcus casseliflavus, Enterococcus raffinosus and Enterococcus hirae was selected for testing. The isolates originated from NCTC collections (n = 12), a retrospective collection of bacteremia isolates from Cambridge University Hospitals (CUH) NHS Foundation Trust (2006–2012, n = 15), and from a meat sample (n = 1) (Table 1). They included isolates with vanA and vanB acquired resistance, and in the case of E. faecalis and E. faecium bacteremia isolates, a range of diverse hospital-adapted STs Raven et al., 2016 (link), Raven et al., 2016 ). The organisms were grown from glycerol bead vials stored at −80°C onto Columbia blood agar (CBA, Oxoid) and 200 μl of a 0.5 McFarland suspension was streaked using the four-quadrant technique onto chromID VRE agar (bioMérieux) and Brilliance VRE agar (Oxoid). Growth was assessed after 24 and 48 hours aerobic incubation at 37 °C. Vancomycin minimum inhibitory concentration was measured using Etest (bioMérieux).