Infections caused by hypervirulent Klebsiella pneumoniae (hvKp) are often characterised by severe, metastatic and relapsing infections. Initially described in Asia, this pathotype has now expanded worldwide. Convergent strains combining hypervirulence with multidrug resistance additionally aggravate the situation. However, only sparse data are available on the occurrence of hvKp in European countries. Therefore, this study investigated the prevalence of hvKp in a tertiary medical centre in Germany.

K. pneumoniae isolates were prospectively collected from clinical specimens obtained at the University Medicine Greifswald from June 1st to August 31st, 2022. Only the first isolate from each patient was considered, while screening samples were excluded. All isolates were phenotypically characterised for virulence and subjected to whole genome sequencing (WGS).

A total of 122 isolates were included, which ranged from largely antibiotic-susceptible to multidrug-resistant phenotypes, with only one isolate carrying a carbapenemase gene (blaOXA-181). Phenotypic assays showed heterogeneous results, with only one isolate demonstrating concomitant positivity in both the string test and mucoid-staining plate. WGS revealed 81 different sequence types, including high-risk clonal lineages. Four isolates carried typical genetic markers associated with hypervirulence and were largely antibiotic-susceptible. In the Galleria mellonella infection model, these four isolates showed higher larval mortality compared to two control carbapenem-resistant classical K. pneumoniae strains. Convergent strains were not found.

Our findings revealed that 3.3 % (4 out of 122) of isolates were classified as hvKp. This prevalence appears clinically relevant due to the notoriously aggressive course of infections caused by this pathotype.

Hypervirulent Klebsiella pneumoniae

Prevalence

Clinical relevance

Virulence

Phenotypic characterisation

Whole genome sequencing

© 2025 The Authors. Published by Elsevier GmbH.