Dissemination of Verona Integron-encoded Metallo-β-lactamase among clinical and environmental Enterobacteriaceae isolates in Ontario, Canada

Abstract

AbstractSurveillance data from Southern Ontario show that a majority of Verona Integron-encoded Metallo-β-lactamase (VIM)-producingEnterobacteriaceaeare locally acquired. To better understand the local epidemiology, we analysed clinical and environmentalblaVIM-positiveEnterobacteriaceaefrom the area. Clinical samples were collected within the Toronto Invasive Bacterial Diseases Network (2010–2016); environmental water samples were collected in 2015. We gathered patient information on place of residence and hospital admissions prior to the diagnosis. Patients with and without plausible source of acquisition were compared regarding risk exposures. Microbiological isolates underwent whole-genome sequencing (WGS);blaVIMcarrying plasmids were characterized. We identified 15 patients, thereof 11 withblaVIM-1-positiveEnterobacter hormaecheiwithin two genetic clusters based on WGS. Whereas no obvious epidemiologic link was identified among cluster I patients, those in cluster II were connected to a hospital outbreak. Except for patients with probable acquisition abroad, we did not identify any further risk exposures. TwoblaVIM-1-positiveE. hormaecheifrom environmental waters matched with the clinical clusters; plasmid sequencing suggested a common ancestor plasmid for the two clusters. These data show that both clonal spread and horizontal gene transfer are drivers of the dissemination ofblaVIM-1-carryingEnterobacter hormaecheiin hospitals and the aquatic environment in Southern Ontario, Canada.