Anca Rath (Regensburg / DE), Bärbel Kieninger (Regensburg / DE), Nilufarbayim Mirzaliyeva (Regensburg / DE), Guido Werner (Wernigerode / DE), Jennifer Bender (Wernigerode / DE), Martin Fischer (Wernigerode / DE), Adriana Cabal-Rosel (Wien / AT), Werner Ruppitsch (Graz / AT), Milo Halabi (Ried / AT), Anna Hörtenhuber (Steyr / AT), Wolfgang Prammer (Steyr / AT), Yarub Salaheddin (Steyr / AT), Heidrun Kerschner (Linz / AT), Rainer Hartl (Linz / AT), Martin Ehrenschwender (Regensburg / DE), Andreas Ambrosch (Regensburg / DE), Helena Seth-Smith (Zürich / CH), Levin Joe Klages (Bielefeld / DE), Aila Caplunik-Pratsch (Regensburg / DE), Anja Eichner (Regensburg / DE), Jürgen Fritsch (Regensburg / DE), Wulf Schneider-Brachert (Regensburg / DE)
Introduction: Understanding dynamics and spreading patterns of novel vancomycin-resistant enterococci (VRE) strains could be the key to stopping their worldwide spread. The occurrence and explosive expansion of the novel strain ST1299 in Germany and Upper Austria gives us the opportunity to gain a more detailed insight.
Methods: The surveillance at a tertiary care hospital in southern Germany includes identification by mass spectrometry and vanA/B-PCR, then whole-genome sequencing (WGS) of at least one VRE isolate per van-genotype, patient and year since 2004. Isolates were identified by database inquiry for "ST1299", followed by selection of one isolate per patient and year. Further ST1299 isolate sources are 1) a further tertiary care hospital in Regensburg, 2) the National Reference Center for Enterococci, and 2.) outbreak isolates from Upper Austria.
Results: From 2018 - 2022, 622 VRE isolates were assigned to ST1299 with 100% vanA-genotype (488 Regensburg County, 98 Germany other, 34 Upper Austria). In Regensburg most isolates were detected in rectal swabs (58.4%), urine (24.0%) or blood cultures (5.3%). The first four isolates were detected in 2018, but explosive expansion started April 2019 substantiated by an outbreak in a COVID-19 quarantine department. Thereafter spread was accelerated by several outbreaks throughout the hospital. ST1299 numbers culminated in January-March 2022 (overall 79 isolates), whereas the most common complex type (CT) was ST1299/CT1903 (67.3%). This strain also reached Upper Austria by December 2021, where it caused four hospital outbreaks with up to 25 patients. ST1299/CT3109, the second most common CT (24.0%), was only detected starting 2020, but had a similarly dynamic expansion and even surpassed ST1299/CT1903 in Regensburg during Q1/2022. Overall, only 54 isolates were assigned to other CTs. Currently, further data acquisition on strain dynamics and clinical outbreaks is still in progress.
Conclusion: Since its first appearance in 2018, the strain ST1299 has proven highly transmissible, and has managed to expand throughout southeastern Germany and Upper Austria.