A Sustained Hospital Outbreak of Vancomycin-Resistant Enterococcus faecium Bacteremia due to Emergence of vanB E. faecium Sequence Type 203

Abstract

BACKGROUND: A significant increase in the rate of vancomycin-resistant Enterococcus faecium (VREfm) bacteremia at our health service, despite improved infection control, prompted us to investigate the cause. METHODS: E. faecium bacteremia (including VREfm) over a 12-year period (1998-2009) was investigated using multilocus sequence typing, antibiotic and antiseptic susceptibility profiles, optical mapping, and whole genome sequencing of historical and recent isolates. RESULTS: For 10 years, the rate of bacteremia due to vanB VREfm remained stable and sequence type (ST) 17 was predominant. In 2005, ST203 vancomycin-susceptible E. faecium first appeared at our institution, and from March 2007,..