Successful containment of two vancomycin-resistant Enterococcus faecium (VRE) outbreaks in a Dutch teaching hospital using environmental sampling and whole-genome sequencing.

K B Gast, A J G van Oudheusden, J L Murk, J J J M Stohr, A G Buiting, J J Verweij

The Journal of hospital infection 2021 May

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Vancomycin-resistant enterococci (VRE) may cause nosocomial outbreaks. This article describes all VRE carriers that were identified in 2018 at Elisabeth-Tweesteden Hospital, Tilburg, The Netherlands. To investigate the genetic relatedness of VRE isolates and the possibility of a common environmental reservoir using environmental sampling and whole-genome sequencing (WGS). Infection control measures consisted of contact isolation, contact surveys, point prevalence screening, environmental sampling, cleaning and disinfection. VRE isolates were sequenced using a MiSeq sequencer (Illumina, San Diego, CA, USA), and assembled using SPAdes v.3.10.1. A minimal spanning tree and a neighbour joining tree based on allelic diversity of core-genome multi-locus sequence typing and accessory genes were created using Ridom SeqSphere+ software (Ridom GmbH, Münster, Germany). Over a 1-year period, 19 VRE carriers were identified; of these, 17 were part of two outbreaks. Before environmental cleaning and disinfection, 55 (14%) environmental samples were VRE-positive. Fifty-one isolates (23 patient samples and 28 environmental samples) were available for WGS analysis. Forty-four isolates were assigned to ST117-vanB, five were assigned to ST17-vanB, and two were assigned to ST80-vanB. Isolates from Outbreak 1 (N=22) and Outbreak 2 (N=22) belonged to ST117-vanB; however, WGS showed a different cluster type with 257 allelic differences. WGS of two outbreak strains provided discriminatory information regarding genetic relatedness, and rejected the hypothesis of a common environmental reservoir. A high degree of environmental contamination was associated with higher VRE transmission. Quantification of environmental contamination may reflect the potential for VRE transmission and could therefore support the infection control measures. Copyright © 2021 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Citation

K B Gast, A J G van Oudheusden, J L Murk, J J J M Stohr, A G Buiting, J J Verweij. Successful containment of two vancomycin-resistant Enterococcus faecium (VRE) outbreaks in a Dutch teaching hospital using environmental sampling and whole-genome sequencing. The Journal of hospital infection. 2021 May;111:132-139