Genetic, virulence, and antimicrobial resistance characteristics associated with distinct morphotypes in ST11 carbapenem-resistant Klebsiella pneumoniae

ABSTRACT

ST11 is the most common lineage among carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in Asia. Diverse morphotypes resulting from genetic mutations are associated with significant differences in microbial characteristics among K. pneumoniae isolates. Here, we investigated the genetic determinants and critical characteristics associated with distinct morphotypes of ST11 CRKP. An ST11-KL47 CRKP isolate carrying a pLVPK-like virulence plasmid was isolated from a patient with a bloodstream infection; the isolate had the “mcsw” morphotype. Two distinct morphotypes (“ntrd” and “msdw”) were derived from this strain during in vitro passage. Whole genome sequencing was used to identify mutations that cause the distinct morphotypes of ST11 CRKP. Transmission electron microscopy, antimicrobial susceptibility tests, growth assays, biofilm formation, virulence assays, membrane permeability assays, and RNA-seq analysis were used to investigate the specific characteristics associated with different morphotypes of ST11 CRKP. Compared with the parental mcsw morphotype, the ntrd morphotype resulted from mutation of genes involved in capsular polysaccharide biosynthesis (wza, wzc, and wbaP), a result validated by gene knockout experiments. This morphotype showed capsule deficiency and lower virulence potential, but higher biofilm production. By contrast, the msdw morphotype displayed competition deficiency and increased susceptibility to chlorhexidine and polymyxin B. Further analyses indicated that these characteristics were caused by interruption of the sigma factor gene rpoN by insertion mutations and deletion of the rpoN gene, which attenuated membrane integrity presumably by downregulating the phage shock protein operon. These data expand current understanding of genetic, virulence, and antimicrobial resistance characteristics associated with distinct morphotypes in ST11 CRKP.

KEYWORDS:

• ST11
• morphotype
• virulence
• chlorhexidine
• rpoN

Acknowledgements

We thank Ping Yang and Yinping Lv in the Center of Cryo-Electron Microscopy, Zhejiang University for their technical assistance on Transmission Electron Microscopy.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions

TC, YW, XHC: Data curation, Formal analysis, Investigation, Methodology, Project administration and Writing – original draft. LYX, PL, XTW, YBC, QXL: Data curation, Formal analysis, and Methodology. PS, YHX: Conceptualization, Funding acquisition, Data curation, Formal analysis, Supervision and Writing – review & editing.

Data availability statement

The genome sequences of all K. pneumoniae strains were uploaded to GenBank with accession number PRJNA947949. The raw data of RNA-seq was uploaded to SRA with accession numbers PRJNA1016256.

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/21505594.2024.2349768.

Additional information

Funding

This work was supported by the National Key Research and Development Program of China [2021YFC2300300]; Key Research and Development Program of Zhejiang Province [No. 2021C03068]; and Shandong Provincial Laboratory [SYS202202].