Outer membrane vesicles-transmitted virulence genes mediate the emergence of new antimicrobial-resistant hypervirulent Klebsiella pneumoniae

ABSTRACT

Hypervirulent Klebsiella pneumoniae (hvKp) is a notorious clinical pathogen that is more likely to cause severe primary and metastatic abscesses. The dissemination of antimicrobial-resistant hvKp isolates has been reported worldwide, posing a great challenge and severe clinical threat. However, the mechanisms of antimicrobial-resistant hvKp isolates prevalent worldwide are not well precise. Outer membrane vesicles (OMVs) secreted from gram-negative bacteria are an important vehicle for delivering effector molecules inter- and intra-species. To explore whether OMVs as the vector of virulence genes horizontal transfer among Klebsiella pneumoniae and to explain the potential mechanism for the development of antimicrobial-resistant hvKp isolates, we isolated OMVs from hvKp and classical Klebsiella pneumoniae (cKp) by sequential differential centrifugation, respectively. Then, the characteristics and contents of hvKp-OMVs and cKp-OMVs were analyzed. These hvKp-OMVs contain virulence genes, which could be transferred from hvKp horizontally to extended-spectrum beta lactamase (ESBL)-producing cKp, leading to the production of antimicrobial-resistant hypervirulent transformants. Further experiments confirmed the transformants exhibited antimicrobial resistance and hypervirulent phenotypes in vitro and in vivo. In short, this work demonstrated that hvKp-OMVs facilitated virulence genes transfer, allowing an increase in the virulence level of ESBL-producing cKp and providing a new mechanism for the emergence of antimicrobial-resistant hvKp isolates.

KEYWORDS:

• Outer membrane vesicles
• hypervirulent klebsiella pneumoniae
• horizontal gene transfer
• virulence genes

Disclosure statement

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

Ethical approval

All the research involving bacteria were approved by the Medical Ethics Committee of Southern Medical University (number:AF/SQ-04/01.0). All the research involving animal were approved by the Medical Ethics Committee of Southern Medical University (number:K2021016).

Statistical analyses

Prism 8.0 (GraphPad Software) was used for statistical analysis. A P value ≤ 0.05 was used to determine significance. Each data point was repeated at least three times independently.

Additional information

Funding

This research was funded by grant from the National Natural Science Foundation of China [grant number 82072334].