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Molecular and virulence differences of Klebsiella pneumoniae isolated from blood
Zhaoxia Xu1, Yuxuan Xiong2, Xueguang Duan1
1Department of Clinical Laboratory, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China.
Background:
Bloodstream infections (BSIs) accompanied by sepsis with Klebsiella pneumoniae (K. pneumoniae) represents a public health threat being potentially life-threatening. There have been an increasing number of reports on K. pneumoniae isolates in China. We conducted a case-based genomic and experimental study. We studied the diversity of K. pneumoniae isolated from blood causing sepsis to reveal differences between patients.
Methods:
The isolates from six patients infected with K. pneumoniae from January 2022 to April 2023 were analyzed by antimicrobial susceptibility testing and sequenced by whole genome sequencing (WGS). The data collected were used to investigate their serotype, molecular subtype, and virulence-associated and antimicrobial resistance (AMR) genes contents as well as the presence of plasmids.
Results:
WGS data revealed that six isolates clustered in 5 different genetic types, 3 of which identified as carbapenem-resistant K. pneumoniae (CRKp) isolates, 2 as hypervirulent K. pneumoniae (hvKp) isolates. Among them, the serotype of Kpn3 is ST950, which is a relatively new serotype strain in China. CRKp isolates were resistant to almost all antibiotics and carries multiple plasmids with different resistance genes. They all contained the KPC-2 gene, but their bla KPC-2-harbored plasmids were different. 2 hvKp isolates belonged to 2 different sequence types, ST23 and ST65, respectively. HvKp with a hypermucoviscosity phenotype had a higher mortality rate in mice. However, they had less plasmid and antimicrobial resistance genes than CRKp, and were susceptible to all tested antimicrobial drugs.
Conclusion:
This study provided important insights into the diversity between K. pneumoniae strains isolated from blood in the same hospital. K. pneumoniae isolated from different patients has diversity of drug resistance genes, virulence genes and plasmids, which may affect the outcome of patients. Therefore, accurate treatment of patients according to the molecular characteristics and drug resistance phenotype of the isolates will achieve better efficacy.
Insights
Klebsiella pneumoniae bloodstream infections show significant diversity in drug resistance and virulence. Understanding these differences is key to effective patient treatment and combating this public health threat.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Bloodstream infections (BSIs) with Klebsiella pneumoniae (K. pneumoniae) sepsis pose a life-threatening public health risk.
- Increasing reports of K. pneumoniae isolates in China necessitate further investigation.
- A case-based genomic and experimental study was conducted to understand patient-specific K. pneumoniae diversity.
Purpose of the Study:
- To investigate the diversity of K. pneumoniae strains isolated from blood cultures in patients with sepsis.
- To differentiate K. pneumoniae isolates based on genetic type, serotype, virulence factors, and antimicrobial resistance (AMR) profiles.
- To correlate molecular characteristics with patient outcomes.
Main Methods:
- Whole genome sequencing (WGS) and antimicrobial susceptibility testing were performed on six K. pneumoniae isolates from patients between January 2022 and April 2023.
- Analysis included determination of serotype, molecular subtype, virulence-associated genes, AMR genes, and plasmid content.
- Experimental models were used to assess the virulence of hypervirulent K. pneumoniae (hvKp) isolates.
Main Results:
- WGS revealed five distinct genetic types among the six isolates, including three carbapenem-resistant (CRKp) and two hypervirulent (hvKp) K. pneumoniae strains.
- CRKp isolates exhibited resistance to most antibiotics, carried multiple resistance plasmids, and harbored the KPC-2 gene on different plasmids.
- HvKp isolates, while susceptible to all tested antimicrobials, showed a higher mortality rate in mice, indicating significant virulence despite fewer resistance genes.
Conclusions:
- Significant diversity exists in drug resistance genes, virulence factors, and plasmids among K. pneumoniae strains from different patients within the same hospital.
- These molecular differences can impact patient outcomes.
- Tailoring patient treatment based on the molecular characteristics and drug resistance phenotype of K. pneumoniae isolates is crucial for improving therapeutic efficacy.
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