Background: A large outbreak with different clones of vancomycin-resistant enterococci (VRE) affected the Bern University Hospital group for several months. The aim of this study was to describe the extent of the outbreak, using whole genome sequencing.
Methods: Triggered by two cases of VRE bloodstream infections on our hemato-oncology ward, an outbreak investigation was started. Microbiological diagnosis of VRE was obtained by culture and PCR. Epidemiological links were assessed by meticulous chart review and supplemented with whole genome sequencing (WGS) analyses. Multiple infection control measures were implemented to avoid further transmissions.
Results: Between December 2017 and April 2018, 2877 screening samples were obtained from 1200 patients. Three out of six hospitals within the Bern University Hospital group were affected. 83 patients (6.9%) were colonized with VR Enterococcus faecium. Of those, 76 (91.6%) had a strain carrying vanB, with 70 (84%) isolates virtually identical (separated by up to two alleles) by cgMLST and identified as MLST type ST796 (Figure). The remaining seven patients (8.4%) were colonized with vanA carrying strains from five different STs. Five patients (7%) developed an invasive infection with VRE ST796. Temporo-spatial links were found in most patients carrying the outbreak strain. In order to control the outbreak, extensive infection control measures were implemented. By April 2018 the outbreak was contained with these specific measures.
Conclusion: This VRE outbreak was characterized by a rapid intra- and inter-institutional spread of the emergent clone ST796. This clone was recently described in Australia and New Zealand but never before in Europe (1) (2). A multi-faceted infection control led to the containment of the outbreak.
1. Mahony AA, et al. Vancomycin-resistant Enterococcus faecium sequence type 796 - rapid international dissemination of a new epidemic clone. Antimicrob Resist Infect Control. 2018:7:44.
2. Leong KWCet al. Emergence of Vancomycin-Resistant Enterococcus faecium at an Australian Hospital: A Whole Genome Sequencing Analysis. Sci Rep. 2018:8(1):6274.
3. de Been M, et al. Core Genome Multilocus Sequence Typing Scheme for High- Resolution Typing of Enterococcus faecium. J Clin Microbiol. 2015:53(12):3788-97.
Y. Fietze, None
C. Casanova, None
H. Seth-Smith, None
A. Egli, None
J. Marschall, None
N. Buetti, None