Transcriptomic and phenotype analysis revealed the role of rpoS in stress resistance and virulence of a novel ST3355 ESBL-producing hypervirulent Klebsiella pneumoniae isolate

Front Cell Infect Microbiol. 2023 Oct 23:13:1259472. doi: 10.3389/fcimb.2023.1259472. eCollection 2023.

Abstract

Introduction: An extended-spectrum beta-lactamase (ESBL)-hypervirulent Klebsiella pneumoniae (HvKP) strain HKE9 was isolated from the blood in an outpatient.

Methods: The effect of the global regulatory factor RpoS on antimicrobial resistance, pathogenicity, and environmental adaptability was elucidated.

Results: HKE9 is a novel ST3355 (K20/O2a) hypervirulent strain with a positive string test and resistant to cephems except cefotetan. It has a genome size of 5.6M, including two plasmids. CTX-M-15 was found in plasmid 2, and only ompk37 was found in the chromosome. HKE9 could produce bacterial siderophores, and genes of enterobactin, yersiniabactin, aerobactin, and salmochelin have been retrieved in the genome. As a global regulatory factor, knockout of rpoS did not change antimicrobial resistance or hemolytic phenotype while increasing the virulence to Galleria mellonella larvae and showing higher viscosity. Moreover, rpoS knockout can increase bacterial competitiveness and cell adhesion ability. Interestingly, HKE9-M-rpoS decreased resistance to acidic pH, high osmotic pressure, heat shock, and ultraviolet and became sensitive to disinfectants (H2O2, alcohol, and sodium hypochlorite). Although there were 13 Type 6 secretion system (T6SS) core genes divided into two segments with tle1 between segments in the chromosome, transcriptomic analysis showed that rpoS negatively regulated T4SS located on plasmid 2, type 1, and type 3 fimbriae and positively regulate genes responsible for acidic response, hyperosmotic pressure, heat shock, oxidative stress, alcohol and hypochlorous acid metabolism, and quorum sensing.

Discussion: Here, this novel ST3355 ESBL-HvKP strain HKE9 may spread via various clonal types. The important regulation effect of rpoS is the enhanced tolerance and resistance to environmental stress and disinfectants, which may be at the cost of reducing virulence and regulated by T4SS.

Keywords: ESBLs; T4SS; environmental stress and disinfectants tolerance; hypervirulent Klebsiella pneumoniae; pathogenomic; rpoS; virulence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Infective Agents* / pharmacology
  • Disinfectants* / pharmacology
  • Hydrogen Peroxide / pharmacology
  • Klebsiella pneumoniae
  • Phenotype
  • Transcriptome
  • Virulence / genetics
  • Virulence Factors / genetics
  • Virulence Factors / pharmacology
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism

Substances

  • Virulence Factors
  • Hydrogen Peroxide
  • beta-Lactamases
  • Disinfectants
  • Anti-Infective Agents

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was funded by the National Natural Science Foundation of China (No. 82173526) and the Natural Science Basic Research Program of Shaanxi Province, China (No. 2019JM-445).