Surveillance of vancomycin-resistant enterococci reveals shift in dominating clusters from to clusters, Denmark, 2015 to 2022.

BackgroundVancomycin-resistant enterococci (VRE) are increasing in Denmark and Europe. Linezolid and vancomycin-resistant enterococci (LVRE) are of concern, as treatment options are limited. Vancomycin-variable enterococci (VVE) harbour the gene complex but are phenotypically vancomycin-susceptible.AimThe aim was to describe clonal shifts for VRE and VVE in Denmark between 2015 and 2022 and to investigate genotypic linezolid resistance among the VRE and VVE.MethodsFrom 2015 to 2022, 4,090 Danish clinical VRE and VVE isolates were whole genome sequenced. We extracted vancomycin resistance genes and sequence types (STs) from the sequencing data and performed core genome multilocus sequence typing (cgMLST) analysis for . All isolates were tested for the presence of mutations or genes encoding linezolid resistance.ResultsIn total 99% of the VRE and VVE isolates were From 2015 through 2019, 91.1% of the VRE and VVE were . During 2020, to the number of increased to 254 of 509 VRE and VVE isolates. Between 2015 and 2022, seven clusters dominated: ST80-CT14 , ST117-CT24 , ST203-CT859 ST1421-CT1134 (VVE cluster) ST80-CT1064 , ST117-CT36 and ST80-CT2406 We detected 35 linezolid vancomycin-resistant and eight linezolid-resistant VVEfm.ConclusionFrom 2015 to 2022, the numbers of VRE and VVE increased. The spread of the VVE cluster ST1421-CT1134 in Denmark is a concern, especially since VVE diagnostics are challenging. The finding of LVRE, although in small numbers, ia also a concern, as treatment options are limited.