Detection and characterization of putative hypervirulent Klebsiella pneumoniae isolates in microbiological diagnostics

Bernd Neumann* (First author), Claudia Stürhof, Anca Rath, Bärbel Kieninger, Elias Eger, Justus U Müller, Alexander von Poblocki, Nadja Gerlitz (Co-author), Paul Wollschläger (Co-author), Wulf Schneider-Brachert, Katharina Schaufler, Kathleen Klaper, Jörg Steinmann (Last author)

*Corresponding author for this work

Research output: Contribution to journalOriginal Article (Journal)peer-review


Hypervirulent Klebsiella pneumoniae strains (hvKp) can cause invasive community-acquired infections in healthy patients of all ages. In this study, the prevalence of putative hvKp in a German tertiary center was investigated and hvKp were characterized by phenotypic and molecular assays. All K. pneumoniae isolates in routine microbiological diagnostics from a single center were screened by string-testing over a period of 6 months. String-test positive (≥ 0.5 mm) isolates were re-evaluated on different media and under various conditions (aerobe, anaerobe). For string-test positive isolates, genes (magA, iutA, rmpA and rmpA2) associated with hypermucoviscosity and hypervirulence were amplified by multiplex PCR. PCR-positive isolates were subjected to whole-genome sequencing and sedimentation and biofilm formation assays. From 1310 screened K. pneumoniae isolates in clinical routine 100 isolates (7.6%) were string test positive. From these, 9% (n = 9) were defined as putative hvKp (string-test+/PCR+). Highest rate of string-test-positive isolates was observed on MacConkey agar under aerobic conditions. Amongst these nine putative hvKp isolates, the international lineage ST23 carrying hvKp-plasmid pKpVP-1 was the most common, but also a rare ST86 with pKpVP-2 was identified. All nine isolates showed hypermucoviscosity and weak biofilm formation. In conclusion, 9% of string-positive, respectively 0.69% of all K. pneumoniae isolates from routine were defined as putative hypervirulent. MacConkey agar was the best medium for hvKp screening.

Original languageEnglish
Pages (from-to)19025
JournalScientific reports
Issue number1
Publication statusPublished - 3 Nov 2023


  • Humans
  • Klebsiella pneumoniae
  • Virulence Factors/genetics
  • Virulence/genetics
  • Agar
  • Multiplex Polymerase Chain Reaction
  • Klebsiella Infections/diagnosis
  • Anti-Bacterial Agents


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